The document discusses environmentally friendly composite materials made from natural resources. It describes composites made from biodegradable matrices and reinforcements obtained from renewable materials. Specific matrices discussed include starch, starch-cellulose acetate blends, and polylactic acid (PLA). The document emphasizes that developing sustainable plastic production through biodegradable and low environmental impact processes is important to address the environmental problems caused by most conventional plastics.
Our project on biofuels and bioplasticso6rv76r6uytfitfffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
Flue gas mitigation technology that will aid in alleviating our emissions from point sources (i.e. power plants) by supplementing growth of ALGAE to produces our transportation sector fuels.
This document discusses concepts related to bioplastics and biodegradable plastics. It begins by defining conventional plastics and their properties, as well as bioplastics. There are two types of bioplastics - those derived from biomass and those that are biodegradable. The document then discusses standards for biodegradability and compostability, noting that current standards do not fully capture biodegradation under natural environmental conditions. It also suggests that industry groups have influenced standards and definitions in ways that overstate the sustainability and environmental friendliness of certain bioplastics. In summary, the document provides background on plastics and bioplastics, discusses standards and their limitations, and notes industry influence over definitions and standards
This document presents research on the in vitro degradation of plastic via the microorganisms Micrococcus luteus and Masoniella species. Polystyrene plastic samples and soil samples were collected and various bacteria and fungi were isolated. M. luteus and Masoniella sp. were identified and found to degrade plastic at varying rates when incubated with the plastic for 35, 45, and 55 days. M. luteus degraded up to 32% of plastic weight while Masoniella sp. degraded up to 27.4% of plastic weight over the incubation periods. The study demonstrates that M. luteus and Masoniella sp. have potential for plastic biodegradation.
HYPOBARIC STORAGE AND IRRADIATION IN FRUITS AND VEGETABLESSANKETH ASHOK U
Hypobaric storage and irradiation are methods used to preserve fruits and vegetables. Hypobaric storage involves storing produce at reduced atmospheric pressure and low oxygen levels to decrease respiration and ethylene production, extending storage life. Irradiation exposes produce to ionizing radiation to disinfect and sterilize without adding chemicals, preserving nutrition while increasing quality and shelf life. Both methods significantly lengthen the storage periods of various fruits and vegetables compared to refrigeration alone.
Our project on biofuels and bioplasticso6rv76r6uytfitfffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
Flue gas mitigation technology that will aid in alleviating our emissions from point sources (i.e. power plants) by supplementing growth of ALGAE to produces our transportation sector fuels.
This document discusses concepts related to bioplastics and biodegradable plastics. It begins by defining conventional plastics and their properties, as well as bioplastics. There are two types of bioplastics - those derived from biomass and those that are biodegradable. The document then discusses standards for biodegradability and compostability, noting that current standards do not fully capture biodegradation under natural environmental conditions. It also suggests that industry groups have influenced standards and definitions in ways that overstate the sustainability and environmental friendliness of certain bioplastics. In summary, the document provides background on plastics and bioplastics, discusses standards and their limitations, and notes industry influence over definitions and standards
This document presents research on the in vitro degradation of plastic via the microorganisms Micrococcus luteus and Masoniella species. Polystyrene plastic samples and soil samples were collected and various bacteria and fungi were isolated. M. luteus and Masoniella sp. were identified and found to degrade plastic at varying rates when incubated with the plastic for 35, 45, and 55 days. M. luteus degraded up to 32% of plastic weight while Masoniella sp. degraded up to 27.4% of plastic weight over the incubation periods. The study demonstrates that M. luteus and Masoniella sp. have potential for plastic biodegradation.
HYPOBARIC STORAGE AND IRRADIATION IN FRUITS AND VEGETABLESSANKETH ASHOK U
Hypobaric storage and irradiation are methods used to preserve fruits and vegetables. Hypobaric storage involves storing produce at reduced atmospheric pressure and low oxygen levels to decrease respiration and ethylene production, extending storage life. Irradiation exposes produce to ionizing radiation to disinfect and sterilize without adding chemicals, preserving nutrition while increasing quality and shelf life. Both methods significantly lengthen the storage periods of various fruits and vegetables compared to refrigeration alone.
Role of Microbes in Sewage Treatment, in Biogas production, as Biocontrol age...indranil chatterjee
The document discusses the roles of microbes in sewage treatment, biogas production, and as biocontrol agents and biofertilizers. Microbes play key roles in breaking down waste in sewage treatment plants and converting organic materials into biogas through anaerobic digestion. They also act as natural enemies to control agricultural pests and help fertilize soils by fixing nitrogen and making nutrients available to plants.
NEWater is treated wastewater that has been purified using dual-membrane and ultraviolet technologies for potable use in Singapore. It was developed as a viable source of raw water by the Public Utilities Board and Ministry of the Environment and Water Resources in 1998. NEWater undergoes conventional wastewater treatment followed by microfiltration/ultrafiltration to remove solids and particles, reverse osmosis to remove bacteria, viruses, salts and organic matter, and finally UV disinfection to inactivate any remaining organisms, producing highly purified water that is mostly used for industrial purposes requiring high purity.
Use of microorganisms in wastewater treatmentVAISHALI JAIN
Waste water treatment involves three main processes: primary treatment to remove solids, secondary biological treatment using microorganisms, and tertiary treatment for further polishing. Secondary treatment can occur through trickling filters, activated sludge, rotating biological contactors, and other methods. The treatment relies on beneficial microorganisms like bacteria and protozoa to break down organic waste, but must also remove harmful bacteria and viruses. A variety of microbes and treatment stages are needed to safely clean waste water.
Biodeterioration of paper and leather ppt..ShaistaKhan60
This document discusses the biodeterioration of paper and leather. It defines biodeterioration as the breakdown of materials by microorganisms or undesirable changes caused by organisms. For paper, factors like humidity, chemicals, and microbes like fungi can cause staining, foxing, and weakening. Leather deterioration is also caused by bacteria and fungi when conditions are poor, leading to hardening, deformation, and discoloration. Preventing biodeterioration requires controlling moisture, chemicals, insects, and proper storage conditions.
Microorganism in sewage treatment,Biodiversity and rolesNibal mousa
This document discusses microorganisms found in sewage treatment. It begins by describing the composition of sewage and how it provides an ideal environment for microorganism growth. It then examines the roles of various bacteria, including acetogenic, coliform, denitrifying, fermentative, and nitrifying bacteria. It also discusses archaea like methanogens, as well as algae, fungi, protozoa, and viruses present in sewage treatment. The document provides examples of important microorganisms and their roles in removing pollutants from wastewater.
Water Pollution and its control through biotechnologyRachana Tiwari
Water pollution occurs from both point and non-point sources and can be physical, chemical, or biological in nature. It affects plants and organisms in bodies of water. Biotechnological control of water pollution uses aerobic and anaerobic treatment processes. Aerobic processes use microorganisms like Pseudomonas and algae to break down pollutants, and occur in suspended growth systems like activated sludge or attached growth systems like trickling filters. Anaerobic processes use microbes like Peptococcus anaerobus and Escherichia coli to treat waste in the absence of oxygen in digesters.
Dr. S. Nagarajan discusses the increasing use of plastics and the resulting pollution crisis. Trillions of plastic items are manufactured each year, but only 5% are recycled while the rest end up in the environment. Plastic waste has accumulated in oceans and remains in animal stomachs after death. Various health issues are also linked to plastic exposure. The document then outlines different plastic recycling methods like primary, secondary, and tertiary recycling as well as recycling processes for specific plastics like PET, PVC, and HDPE. It emphasizes that we must address the plastic pollution problem to save the planet and environment for future generations.
Biofilms play an important role in ecology and sustainability by recycling vital elements. Microbes make up most of Earth's biomass and live in biofilms. Beneficial biofilms are used in water treatment by filtering out organic materials using microbes attached to surfaces. Similarly, biofilms are used to treat wastewater and remediate soil and groundwater contamination from spills by introducing bacteria that consume pollutants. Biofilms are also used in mining to extract metals through microbial leaching processes like heap leaching, which is less environmentally harmful than acid leaching.
Composting can be used to remediate contaminated soil. The overall process involves mixing contaminated soil with amendment materials like straw or wood chips in windrows or static piles to stimulate microbial activity. As microbes break down the amendment materials, heat is generated and hazardous chemicals in the soil may be broken down or transformed into innocuous compounds. The design considers factors like pile dimensions, moisture levels, aeration, and inoculating the soil with microbes to optimize treatment.
Bio-plastics are plastics that are either derived from renewable biomass sources like vegetable oils or are biodegradable. There are several types of bio-plastics including starch-based, cellulose-based, and aliphatic polyesters like PLA and PHA which are produced by bacteria. Compared to conventional plastics, bio-plastics have benefits like lower carbon emissions, lower toxicity, and some can biodegrade, but they also have drawbacks like higher costs and potential issues with GMOs. Bio-plastics production is growing due to advantages for certain applications and their more environmentally friendly nature.
The textile industry poses major environmental hazards due to its extensive use of chemicals and water throughout the manufacturing process. It releases billions of gallons of wastewater contaminated with dyes, bleaches, and other chemicals each year. O Ecotextiles aims to raise awareness of these issues and produce fabrics through non-toxic, sustainable methods like using organic fibers that don't require pesticides, treating wastewater before release, and employing natural dyes and finishes. It advocates for environmentally preferable practices across the textile industry to reduce pollution and promote sustainability.
1) The document summarizes a student project on using banana and potato peels to filter salt from sea water for irrigation purposes.
2) The students designed a product using banana and potato peels to soak in sea water, which removes salt through the starch in the peels.
3) Testing showed the water was suitable for planting, providing a low-cost way to desalinate water using agricultural waste for countries relying on sea water.
Ethnic Processed Food Using Hurdle TechnologyDhanupriya S
This document describes the production of Thalipu Vadagam, a seasoned ingredient used in South Indian cuisine. It contains onion, garlic, mustard seeds, fenugreek seeds, split black gram, cumin seeds, salt, turmeric powder, and castor oil. The ingredients are chopped, salted to cure for 48 hours, molded into balls with oil, and sun-dried for 10 days. Onion and garlic contain antimicrobial compounds like allicin and flavonoids. When combined with the other spices, Thalipu Vadagam can inhibit microorganisms like salmonella, E. coli, and various molds. The production process uses techniques like low moisture, acidity, antioxid
This document discusses various types of bioremediation techniques used to clean up contaminated soil and groundwater. It defines bioremediation as using living microorganisms to degrade environmental pollutants or prevent pollution. The two main types of bioremediation are in situ, which treats contaminants in place, and ex situ, which involves removing contaminated material to be treated elsewhere. Specific techniques discussed include bioaugmentation, bioslurping, biosparging, natural attenuation, bioventing, and biostimulation. The advantages and limitations of bioremediation are also summarized.
The ongoing growth of human population has led to the accumulation of tons of non-degradable plastic. Therefore, the urge to find prompt solution is a necessity. Herein, a graduation project of undergraduate students from faculty of pharmacy, Beni-Suef University, Egypt based on previous research.
Nanotechnology in waste water treatmentSakthivel R
This document discusses how nanotechnology can be used for waste water treatment. It explains that nanoparticles are effective at removing pollutants from water due to their high surface area. Various nanomaterials like metal nanoparticles, carbon nanomaterials, and zeolites can be used. Specifically, nano sorbents can sorbe a wide variety of organic and inorganic contaminants, nano catalysts can increase reaction rates to degrade contaminants, and biomimetic membranes allow for efficient desalination using reverse osmosis. Molecularly imprinted polymers also selectively remove pollutants even at low concentrations. Overall, nanotechnology provides effective, efficient, and eco-friendly approaches to water treatment.
Green plastics :an emerging alternative of petroleum based plasticsAntu Bhattacharjee
This document discusses green plastics as an alternative to petroleum-based plastics. It provides background on plastics and their environmental issues. Green plastics are made from renewable sources like plants, and are biodegradable. Examples include polylactic acid and polyhydroxybutyrate. Green plastics have advantages over conventional plastics like reduced greenhouse gas emissions, no use of petrochemicals, and biodegradability. The document discusses different types of green plastics and their production processes, as well as standards, costs, and ways to promote their use.
This document summarizes the history and development of plastics. It discusses how plastics originated from natural resins and cellulose derivatives in the 1860s. Major milestones included the development of Bakelite in the early 1900s and nylon in the 1930s. World War II provided a boost to plastics development as alternatives were needed for scarce natural materials. Common plastics developed after the war include polyethylene and polypropylene. Plastics are classified based on their chemical structure and have a wide range of uses but also disadvantages like non-biodegradability and contribution to pollution.
This document provides an overview of bioremediation. Some key points:
- Bioremediation uses microorganisms like bacteria and fungi to remove or break down pollutants in the environment. It can be used to treat contamination in soil, water, and solid waste.
- There are different types of bioremediation including biostimulation, bioaugmentation, and intrinsic bioremediation. Genetically engineered microbes are also used.
- The microbes degrade pollutants through redox reactions and metabolic pathways. Bioremediation can be done on-site (in situ) or by removing contaminated material to another location (ex situ).
This document summarizes a project on bioremediating lead pollution in water. The project aims to isolate lead-degrading bacteria from contaminated sites and identify genes responsible for lead degradation. Bacteria were cultured from polluted soil and water samples. Preliminary results showed isolation of various Bacillus species that can grow in lead concentrations. Future work involves inducing bioluminescence in isolated bacteria to detect the presence of lead in water.
This document provides an overview of biodegradable polymers. It begins by defining biodegradable polymers as polymeric materials that can be broken down by microorganisms such as bacteria and fungi into carbon dioxide, water and biomass. It then discusses the history of biodegradable polymers and describes the three main classes: conventional non-biodegradable plastics, partially degradable plastics containing natural fibers, and completely biodegradable plastics derived from natural sources like starch. The document also outlines the types of biodegradable polymers including naturally occurring resins like starch and proteins, and biodegradable synthetic resins. Finally, it discusses applications of biodegradable polymers in packaging.
Plastic has brought immense benefits to the whole human race. The light weight, cheap chemical resistant and strong material has got almost omnipotent presence. When we talk of its strength we talk of the time till it survives and to everyone’s knowledge plastic does not bio-degrade. Yes, plastic the greatest invention of mankind has the power to even destroy mankind. Plastic that is not biodegradable brings a lot of environmental issues. It deteriorates the ozone layer. For the most part plastic is produced from oil. The world is progressively running out of oil. Research says plastic brings number of harms not only to humans but also the entire cosmos. The plastic which cannot be recycled has to be disposed off in some or the other way. Let’s say if we dispose in water it has the tendency to destroy marine life. So the only way left to reduce the ill effects of plastic is to use eco-friendly or biodegradable plastic. Biodegradable plastics are plastics that will decay in usual aerobic environments.
See More at : http://goo.gl/84r5cM
http://www.entrepreneurindia.co/
Tags
Bio plastics Business, Biodegradable and compostable alternatives to conventional plastics, Biodegradable plastic products, Biodegradable Plastics, Biodegradable Plastics and Polymers, Biodegradable Plastics and Polymers Based Profitable Projects, Biodegradable Plastics and Polymers Based Small Scale Industries Projects, Biodegradable Plastics and Polymers Business, Biodegradable Plastics and Polymers Industry in India, Biodegradable Plastics and Polymers Projects, Biodegradable Plastics and Polymers Small Business Manufacturing, Biodegradable Plastics business, Biodegradable Plastics Eco Friendly Plastics, Biodegradable plastics from polylactic acid, Biodegradable plastics from renewable sources, Biodegradable plastics from wheat starch, Biodegradable Plastics: Starting a business, Biodegradable polymer, Biodegradable Polymers and Plastics, Biodegradable polyolefins, Biodegradation of acylated sugar-linked poly(styrene Maleic anhydride), Biomineralization of the sugar-linked poly(styrene maleic Anhydride), Biopolymers and Biodegradable Plastics, Biotechnology, Business consultancy, Business consultant, Business guidance for Biodegradable Plastics and Polymers industry, Business guidance to clients, Business Plan for a Startup Business, Business start-up, Degradable plastics for composting, Good Scope in Biodegradable Plastic Products, Great Opportunity for Startup, How are bioplastics made, How to Start a Biodegradable Plastics and Polymers Business, How to start a successful Biodegradable Plastics and Polymers business, How to Start Biodegradable Plastics and Polymers Industry in India, How to start plastic recycling business, Managing Bioplastics Business Innovation in Start up, modern small and cottage scale industries, Most Profitable Biodegradable Plastics and Polymers Business Ideas
Role of Microbes in Sewage Treatment, in Biogas production, as Biocontrol age...indranil chatterjee
The document discusses the roles of microbes in sewage treatment, biogas production, and as biocontrol agents and biofertilizers. Microbes play key roles in breaking down waste in sewage treatment plants and converting organic materials into biogas through anaerobic digestion. They also act as natural enemies to control agricultural pests and help fertilize soils by fixing nitrogen and making nutrients available to plants.
NEWater is treated wastewater that has been purified using dual-membrane and ultraviolet technologies for potable use in Singapore. It was developed as a viable source of raw water by the Public Utilities Board and Ministry of the Environment and Water Resources in 1998. NEWater undergoes conventional wastewater treatment followed by microfiltration/ultrafiltration to remove solids and particles, reverse osmosis to remove bacteria, viruses, salts and organic matter, and finally UV disinfection to inactivate any remaining organisms, producing highly purified water that is mostly used for industrial purposes requiring high purity.
Use of microorganisms in wastewater treatmentVAISHALI JAIN
Waste water treatment involves three main processes: primary treatment to remove solids, secondary biological treatment using microorganisms, and tertiary treatment for further polishing. Secondary treatment can occur through trickling filters, activated sludge, rotating biological contactors, and other methods. The treatment relies on beneficial microorganisms like bacteria and protozoa to break down organic waste, but must also remove harmful bacteria and viruses. A variety of microbes and treatment stages are needed to safely clean waste water.
Biodeterioration of paper and leather ppt..ShaistaKhan60
This document discusses the biodeterioration of paper and leather. It defines biodeterioration as the breakdown of materials by microorganisms or undesirable changes caused by organisms. For paper, factors like humidity, chemicals, and microbes like fungi can cause staining, foxing, and weakening. Leather deterioration is also caused by bacteria and fungi when conditions are poor, leading to hardening, deformation, and discoloration. Preventing biodeterioration requires controlling moisture, chemicals, insects, and proper storage conditions.
Microorganism in sewage treatment,Biodiversity and rolesNibal mousa
This document discusses microorganisms found in sewage treatment. It begins by describing the composition of sewage and how it provides an ideal environment for microorganism growth. It then examines the roles of various bacteria, including acetogenic, coliform, denitrifying, fermentative, and nitrifying bacteria. It also discusses archaea like methanogens, as well as algae, fungi, protozoa, and viruses present in sewage treatment. The document provides examples of important microorganisms and their roles in removing pollutants from wastewater.
Water Pollution and its control through biotechnologyRachana Tiwari
Water pollution occurs from both point and non-point sources and can be physical, chemical, or biological in nature. It affects plants and organisms in bodies of water. Biotechnological control of water pollution uses aerobic and anaerobic treatment processes. Aerobic processes use microorganisms like Pseudomonas and algae to break down pollutants, and occur in suspended growth systems like activated sludge or attached growth systems like trickling filters. Anaerobic processes use microbes like Peptococcus anaerobus and Escherichia coli to treat waste in the absence of oxygen in digesters.
Dr. S. Nagarajan discusses the increasing use of plastics and the resulting pollution crisis. Trillions of plastic items are manufactured each year, but only 5% are recycled while the rest end up in the environment. Plastic waste has accumulated in oceans and remains in animal stomachs after death. Various health issues are also linked to plastic exposure. The document then outlines different plastic recycling methods like primary, secondary, and tertiary recycling as well as recycling processes for specific plastics like PET, PVC, and HDPE. It emphasizes that we must address the plastic pollution problem to save the planet and environment for future generations.
Biofilms play an important role in ecology and sustainability by recycling vital elements. Microbes make up most of Earth's biomass and live in biofilms. Beneficial biofilms are used in water treatment by filtering out organic materials using microbes attached to surfaces. Similarly, biofilms are used to treat wastewater and remediate soil and groundwater contamination from spills by introducing bacteria that consume pollutants. Biofilms are also used in mining to extract metals through microbial leaching processes like heap leaching, which is less environmentally harmful than acid leaching.
Composting can be used to remediate contaminated soil. The overall process involves mixing contaminated soil with amendment materials like straw or wood chips in windrows or static piles to stimulate microbial activity. As microbes break down the amendment materials, heat is generated and hazardous chemicals in the soil may be broken down or transformed into innocuous compounds. The design considers factors like pile dimensions, moisture levels, aeration, and inoculating the soil with microbes to optimize treatment.
Bio-plastics are plastics that are either derived from renewable biomass sources like vegetable oils or are biodegradable. There are several types of bio-plastics including starch-based, cellulose-based, and aliphatic polyesters like PLA and PHA which are produced by bacteria. Compared to conventional plastics, bio-plastics have benefits like lower carbon emissions, lower toxicity, and some can biodegrade, but they also have drawbacks like higher costs and potential issues with GMOs. Bio-plastics production is growing due to advantages for certain applications and their more environmentally friendly nature.
The textile industry poses major environmental hazards due to its extensive use of chemicals and water throughout the manufacturing process. It releases billions of gallons of wastewater contaminated with dyes, bleaches, and other chemicals each year. O Ecotextiles aims to raise awareness of these issues and produce fabrics through non-toxic, sustainable methods like using organic fibers that don't require pesticides, treating wastewater before release, and employing natural dyes and finishes. It advocates for environmentally preferable practices across the textile industry to reduce pollution and promote sustainability.
1) The document summarizes a student project on using banana and potato peels to filter salt from sea water for irrigation purposes.
2) The students designed a product using banana and potato peels to soak in sea water, which removes salt through the starch in the peels.
3) Testing showed the water was suitable for planting, providing a low-cost way to desalinate water using agricultural waste for countries relying on sea water.
Ethnic Processed Food Using Hurdle TechnologyDhanupriya S
This document describes the production of Thalipu Vadagam, a seasoned ingredient used in South Indian cuisine. It contains onion, garlic, mustard seeds, fenugreek seeds, split black gram, cumin seeds, salt, turmeric powder, and castor oil. The ingredients are chopped, salted to cure for 48 hours, molded into balls with oil, and sun-dried for 10 days. Onion and garlic contain antimicrobial compounds like allicin and flavonoids. When combined with the other spices, Thalipu Vadagam can inhibit microorganisms like salmonella, E. coli, and various molds. The production process uses techniques like low moisture, acidity, antioxid
This document discusses various types of bioremediation techniques used to clean up contaminated soil and groundwater. It defines bioremediation as using living microorganisms to degrade environmental pollutants or prevent pollution. The two main types of bioremediation are in situ, which treats contaminants in place, and ex situ, which involves removing contaminated material to be treated elsewhere. Specific techniques discussed include bioaugmentation, bioslurping, biosparging, natural attenuation, bioventing, and biostimulation. The advantages and limitations of bioremediation are also summarized.
The ongoing growth of human population has led to the accumulation of tons of non-degradable plastic. Therefore, the urge to find prompt solution is a necessity. Herein, a graduation project of undergraduate students from faculty of pharmacy, Beni-Suef University, Egypt based on previous research.
Nanotechnology in waste water treatmentSakthivel R
This document discusses how nanotechnology can be used for waste water treatment. It explains that nanoparticles are effective at removing pollutants from water due to their high surface area. Various nanomaterials like metal nanoparticles, carbon nanomaterials, and zeolites can be used. Specifically, nano sorbents can sorbe a wide variety of organic and inorganic contaminants, nano catalysts can increase reaction rates to degrade contaminants, and biomimetic membranes allow for efficient desalination using reverse osmosis. Molecularly imprinted polymers also selectively remove pollutants even at low concentrations. Overall, nanotechnology provides effective, efficient, and eco-friendly approaches to water treatment.
Green plastics :an emerging alternative of petroleum based plasticsAntu Bhattacharjee
This document discusses green plastics as an alternative to petroleum-based plastics. It provides background on plastics and their environmental issues. Green plastics are made from renewable sources like plants, and are biodegradable. Examples include polylactic acid and polyhydroxybutyrate. Green plastics have advantages over conventional plastics like reduced greenhouse gas emissions, no use of petrochemicals, and biodegradability. The document discusses different types of green plastics and their production processes, as well as standards, costs, and ways to promote their use.
This document summarizes the history and development of plastics. It discusses how plastics originated from natural resins and cellulose derivatives in the 1860s. Major milestones included the development of Bakelite in the early 1900s and nylon in the 1930s. World War II provided a boost to plastics development as alternatives were needed for scarce natural materials. Common plastics developed after the war include polyethylene and polypropylene. Plastics are classified based on their chemical structure and have a wide range of uses but also disadvantages like non-biodegradability and contribution to pollution.
This document provides an overview of bioremediation. Some key points:
- Bioremediation uses microorganisms like bacteria and fungi to remove or break down pollutants in the environment. It can be used to treat contamination in soil, water, and solid waste.
- There are different types of bioremediation including biostimulation, bioaugmentation, and intrinsic bioremediation. Genetically engineered microbes are also used.
- The microbes degrade pollutants through redox reactions and metabolic pathways. Bioremediation can be done on-site (in situ) or by removing contaminated material to another location (ex situ).
This document summarizes a project on bioremediating lead pollution in water. The project aims to isolate lead-degrading bacteria from contaminated sites and identify genes responsible for lead degradation. Bacteria were cultured from polluted soil and water samples. Preliminary results showed isolation of various Bacillus species that can grow in lead concentrations. Future work involves inducing bioluminescence in isolated bacteria to detect the presence of lead in water.
This document provides an overview of biodegradable polymers. It begins by defining biodegradable polymers as polymeric materials that can be broken down by microorganisms such as bacteria and fungi into carbon dioxide, water and biomass. It then discusses the history of biodegradable polymers and describes the three main classes: conventional non-biodegradable plastics, partially degradable plastics containing natural fibers, and completely biodegradable plastics derived from natural sources like starch. The document also outlines the types of biodegradable polymers including naturally occurring resins like starch and proteins, and biodegradable synthetic resins. Finally, it discusses applications of biodegradable polymers in packaging.
Plastic has brought immense benefits to the whole human race. The light weight, cheap chemical resistant and strong material has got almost omnipotent presence. When we talk of its strength we talk of the time till it survives and to everyone’s knowledge plastic does not bio-degrade. Yes, plastic the greatest invention of mankind has the power to even destroy mankind. Plastic that is not biodegradable brings a lot of environmental issues. It deteriorates the ozone layer. For the most part plastic is produced from oil. The world is progressively running out of oil. Research says plastic brings number of harms not only to humans but also the entire cosmos. The plastic which cannot be recycled has to be disposed off in some or the other way. Let’s say if we dispose in water it has the tendency to destroy marine life. So the only way left to reduce the ill effects of plastic is to use eco-friendly or biodegradable plastic. Biodegradable plastics are plastics that will decay in usual aerobic environments.
See More at : http://goo.gl/84r5cM
http://www.entrepreneurindia.co/
Tags
Bio plastics Business, Biodegradable and compostable alternatives to conventional plastics, Biodegradable plastic products, Biodegradable Plastics, Biodegradable Plastics and Polymers, Biodegradable Plastics and Polymers Based Profitable Projects, Biodegradable Plastics and Polymers Based Small Scale Industries Projects, Biodegradable Plastics and Polymers Business, Biodegradable Plastics and Polymers Industry in India, Biodegradable Plastics and Polymers Projects, Biodegradable Plastics and Polymers Small Business Manufacturing, Biodegradable Plastics business, Biodegradable Plastics Eco Friendly Plastics, Biodegradable plastics from polylactic acid, Biodegradable plastics from renewable sources, Biodegradable plastics from wheat starch, Biodegradable Plastics: Starting a business, Biodegradable polymer, Biodegradable Polymers and Plastics, Biodegradable polyolefins, Biodegradation of acylated sugar-linked poly(styrene Maleic anhydride), Biomineralization of the sugar-linked poly(styrene maleic Anhydride), Biopolymers and Biodegradable Plastics, Biotechnology, Business consultancy, Business consultant, Business guidance for Biodegradable Plastics and Polymers industry, Business guidance to clients, Business Plan for a Startup Business, Business start-up, Degradable plastics for composting, Good Scope in Biodegradable Plastic Products, Great Opportunity for Startup, How are bioplastics made, How to Start a Biodegradable Plastics and Polymers Business, How to start a successful Biodegradable Plastics and Polymers business, How to Start Biodegradable Plastics and Polymers Industry in India, How to start plastic recycling business, Managing Bioplastics Business Innovation in Start up, modern small and cottage scale industries, Most Profitable Biodegradable Plastics and Polymers Business Ideas
The document summarizes bioplastics as an alternative to traditional petrochemical plastics. It discusses that bioplastics are derived from renewable plant and microbial sources rather than fossil fuels, and are designed to be biodegradable. The document outlines the advantages of bioplastics in reducing dependence on petrochemicals and related environmental problems. However, it also notes challenges in the costs and proper disposal of bioplastics. The document categorizes different types of bioplastics including starch-based, cellulose-based, and polylactic acid-based bioplastics.
Prevention Of Plastic Pollution And Comparison With PaperJeelkumar Patel
What is Plastic Waste and How to harmful effects of Plastics in nature all things explain. How to manage Plastic Waste Management and explain with case study.
This document provides information on plastic waste reuse, recycling, and disposal with an emphasis on single-use plastics. It defines plastics as petroleum products made of hydrocarbons that are non-biodegradable. It classifies plastics as thermosetting or thermoplastic and lists the most commonly used plastics. The document discusses single-use plastic products, plastic waste generation rates in India, the impacts of plastic pollution, and the government's Plastic Waste Management Rules. It provides responsibilities for local bodies, waste generators, and outlines innovative technologies for plastic waste disposal and management best practices to implement.
IRJET - Study of Polyethylene Terephthalate (PET) Plastic Bottles in Threaded...IRJET Journal
This document studies the use of threaded polyethylene terephthalate (PET) plastic bottles and fly ash as reinforcements in concrete. PET bottles are a common type of plastic waste that is difficult to degrade, requiring recycling or reuse. The study aims to evaluate how using shredded PET bottles and fly ash as partial replacements for cement and aggregates affects the compressive, tensile, and flexural strengths of concrete. Previous research has found strength improvements when plastic fibers or bottles are added to concrete up to a 2% replacement rate of cement or aggregates. The document outlines the materials and methods to be used, including casting concrete cubes with PET bottle and fly ash additions and testing them to determine strength properties. The goal is to develop a more sustainable
Technical presentation on the latest class of environmental friendly class of bio-plastics which are completely degradable and uses low energy. These bio-plastics are widely used in European markets and are being used in food, pharmaceutical and in sanitary products.
#1 INTRODUCTION-The term “plastics” includes materials composed of various elements such as carbon, hydrogen, oxygen, nitrogen, chlorine, and sulphur.
Plastics are macromolecules, formed by polymerization and having the ability to be shaped by the application of reasonable amount of heat and pressure or any other form of forces.
It is one of the few new chemical materials which pose environmental problem.
Polyethylene, polyvinyl chloride, polystyrene is largely used in the manufacturing of plastics.
##2Rapid population growth, urbanization and industrial growth have led to severe problem of waste generation in urban centres.
The waste quantities increased from 46 million tones in 2001 to 65 million tones in 2010.
Report says that per capita per day production will increase to 0.7 kg in 2050.
The characteristics of waste depends on various factors such as food habits, traditions, lifestyle, climate etc.
for more contect
Plastics have become ubiquitous in modern life but also present environmental challenges as waste. This document discusses recycling polymers (plastics) as a solution. It provides background on plastics, noting they are made from petrochemicals and come in various types based on their molecular structure. The document then discusses the environmental impacts of plastic waste, including taking up landfill space, releasing greenhouse gases, and harming wildlife. It stresses that identifying plastics by their identification code is important for effective recycling. Recycling polymers is advocated as it conserves resources and reduces environmental damage from plastic waste.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Here we will see the classifications, Collection, Handling & Sorting, different methods of sorting of plastics
About Biodegradable polymers, how to use it and reuse it
This document provides information about biodegradable plastics, including their types, manufacturing processes, and potential uses. It discusses how biodegradable plastics like directly-expanded starch products and starch-polymer blends are made. The document also outlines the advantages of biodegradable plastics like being renewable and reducing dependence on oil, as well as potential disadvantages like the conditions needed for degradation and effects on soil and water quality. It provides examples of where biodegradable plastics can be found for sale online.
The document discusses plastic waste management in India. It outlines that plastic waste has increased significantly due to population growth and urbanization. It then describes various strategies for plastic waste management, including recycling, landfilling, incineration, using plastic in road construction, co-processing plastic in cement kilns, plasma pyrolysis technology, and converting plastic into liquid fuels. The document emphasizes that plastic waste management is important due to urbanization and that both technological and behavioral challenges still exist.
Production of Conventional Fuel from Plastic Waste and Biomass by PyrolysisIRJET Journal
The document discusses the production of fuel from plastic waste and biomass via pyrolysis. It begins with background information on plastics and biomass. The methodology section describes the experimental setup for pyrolyzing plastic alone or with biomass. Various plastic types and biomass were pyrolyzed alone and in combination. The liquid fuel yield was highest for mixtures containing biomass, ranging from 64-69.6% yield. The quality of the obtained fuels was analyzed and found to be similar to diesel. Residual solids from biomass pyrolysis were converted to nano-silica. Thus, pyrolysis can convert waste plastic and biomass into useful fuels and materials while addressing environmental issues.
Plastic pollution in the marine environment and the marine food webKarl Jaeger
This document discusses plastic pollution in the marine environment and its effects on the marine food web. It outlines that plastic pollution has become a major threat as plastic waste has accumulated in oceans worldwide. The document reviews the types and amounts of plastic debris, including microplastics, found in oceans. It examines how plastics become available to the marine ecosystem and their physical impacts. The document also explores how plastics move through the trophic levels of the marine food web as organisms ingest microplastics and the potential effects on apex predators.
The document discusses the benefits and uses of plastics in various industries such as transportation, medicine, electronics, construction, and packaging. It notes that plastics have improved lives by making products more durable, lightweight and energy efficient. However, the large quantity of plastic waste poses environmental challenges as most plastics are non-biodegradable and their production and disposal releases toxic chemicals. The document advocates reducing single-use plastics and increasing recycling efforts to conserve resources and reduce pollution.
This document provides an overview of bioplastics, including their classification and applications. It discusses that bioplastics are made from renewable sources like plants rather than petroleum, and are often biodegradable. The main types of bioplastics covered are starch-based, polylactic acid, and aliphatic polyesters. Current applications include packaging, food service ware, electronics, and more. The document also notes challenges to bioplastics such as cost, but that the field promises to help the environment and reduce dependence on fossil fuels as the technology advances.
How to Get CNIC Information System with Paksim Ga.pptxdanishmna97
Pakdata Cf is a groundbreaking system designed to streamline and facilitate access to CNIC information. This innovative platform leverages advanced technology to provide users with efficient and secure access to their CNIC details.
Climate Impact of Software Testing at Nordic Testing DaysKari Kakkonen
My slides at Nordic Testing Days 6.6.2024
Climate impact / sustainability of software testing discussed on the talk. ICT and testing must carry their part of global responsibility to help with the climat warming. We can minimize the carbon footprint but we can also have a carbon handprint, a positive impact on the climate. Quality characteristics can be added with sustainability, and then measured continuously. Test environments can be used less, and in smaller scale and on demand. Test techniques can be used in optimizing or minimizing number of tests. Test automation can be used to speed up testing.
OpenID AuthZEN Interop Read Out - AuthorizationDavid Brossard
During Identiverse 2024 and EIC 2024, members of the OpenID AuthZEN WG got together and demoed their authorization endpoints conforming to the AuthZEN API
UiPath Test Automation using UiPath Test Suite series, part 6DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 6. In this session, we will cover Test Automation with generative AI and Open AI.
UiPath Test Automation with generative AI and Open AI webinar offers an in-depth exploration of leveraging cutting-edge technologies for test automation within the UiPath platform. Attendees will delve into the integration of generative AI, a test automation solution, with Open AI advanced natural language processing capabilities.
Throughout the session, participants will discover how this synergy empowers testers to automate repetitive tasks, enhance testing accuracy, and expedite the software testing life cycle. Topics covered include the seamless integration process, practical use cases, and the benefits of harnessing AI-driven automation for UiPath testing initiatives. By attending this webinar, testers, and automation professionals can gain valuable insights into harnessing the power of AI to optimize their test automation workflows within the UiPath ecosystem, ultimately driving efficiency and quality in software development processes.
What will you get from this session?
1. Insights into integrating generative AI.
2. Understanding how this integration enhances test automation within the UiPath platform
3. Practical demonstrations
4. Exploration of real-world use cases illustrating the benefits of AI-driven test automation for UiPath
Topics covered:
What is generative AI
Test Automation with generative AI and Open AI.
UiPath integration with generative AI
Speaker:
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
Ocean lotus Threat actors project by John Sitima 2024 (1).pptxSitimaJohn
Ocean Lotus cyber threat actors represent a sophisticated, persistent, and politically motivated group that poses a significant risk to organizations and individuals in the Southeast Asian region. Their continuous evolution and adaptability underscore the need for robust cybersecurity measures and international cooperation to identify and mitigate the threats posed by such advanced persistent threat groups.
GraphRAG for Life Science to increase LLM accuracyTomaz Bratanic
GraphRAG for life science domain, where you retriever information from biomedical knowledge graphs using LLMs to increase the accuracy and performance of generated answers
CAKE: Sharing Slices of Confidential Data on BlockchainClaudio Di Ciccio
Presented at the CAiSE 2024 Forum, Intelligent Information Systems, June 6th, Limassol, Cyprus.
Synopsis: Cooperative information systems typically involve various entities in a collaborative process within a distributed environment. Blockchain technology offers a mechanism for automating such processes, even when only partial trust exists among participants. The data stored on the blockchain is replicated across all nodes in the network, ensuring accessibility to all participants. While this aspect facilitates traceability, integrity, and persistence, it poses challenges for adopting public blockchains in enterprise settings due to confidentiality issues. In this paper, we present a software tool named Control Access via Key Encryption (CAKE), designed to ensure data confidentiality in scenarios involving public blockchains. After outlining its core components and functionalities, we showcase the application of CAKE in the context of a real-world cyber-security project within the logistics domain.
Paper: https://doi.org/10.1007/978-3-031-61000-4_16
In the rapidly evolving landscape of technologies, XML continues to play a vital role in structuring, storing, and transporting data across diverse systems. The recent advancements in artificial intelligence (AI) present new methodologies for enhancing XML development workflows, introducing efficiency, automation, and intelligent capabilities. This presentation will outline the scope and perspective of utilizing AI in XML development. The potential benefits and the possible pitfalls will be highlighted, providing a balanced view of the subject.
We will explore the capabilities of AI in understanding XML markup languages and autonomously creating structured XML content. Additionally, we will examine the capacity of AI to enrich plain text with appropriate XML markup. Practical examples and methodological guidelines will be provided to elucidate how AI can be effectively prompted to interpret and generate accurate XML markup.
Further emphasis will be placed on the role of AI in developing XSLT, or schemas such as XSD and Schematron. We will address the techniques and strategies adopted to create prompts for generating code, explaining code, or refactoring the code, and the results achieved.
The discussion will extend to how AI can be used to transform XML content. In particular, the focus will be on the use of AI XPath extension functions in XSLT, Schematron, Schematron Quick Fixes, or for XML content refactoring.
The presentation aims to deliver a comprehensive overview of AI usage in XML development, providing attendees with the necessary knowledge to make informed decisions. Whether you’re at the early stages of adopting AI or considering integrating it in advanced XML development, this presentation will cover all levels of expertise.
By highlighting the potential advantages and challenges of integrating AI with XML development tools and languages, the presentation seeks to inspire thoughtful conversation around the future of XML development. We’ll not only delve into the technical aspects of AI-powered XML development but also discuss practical implications and possible future directions.
Threats to mobile devices are more prevalent and increasing in scope and complexity. Users of mobile devices desire to take full advantage of the features
available on those devices, but many of the features provide convenience and capability but sacrifice security. This best practices guide outlines steps the users can take to better protect personal devices and information.
HCL Notes and Domino License Cost Reduction in the World of DLAUpanagenda
Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-and-domino-license-cost-reduction-in-the-world-of-dlau/
The introduction of DLAU and the CCB & CCX licensing model caused quite a stir in the HCL community. As a Notes and Domino customer, you may have faced challenges with unexpected user counts and license costs. You probably have questions on how this new licensing approach works and how to benefit from it. Most importantly, you likely have budget constraints and want to save money where possible. Don’t worry, we can help with all of this!
We’ll show you how to fix common misconfigurations that cause higher-than-expected user counts, and how to identify accounts which you can deactivate to save money. There are also frequent patterns that can cause unnecessary cost, like using a person document instead of a mail-in for shared mailboxes. We’ll provide examples and solutions for those as well. And naturally we’ll explain the new licensing model.
Join HCL Ambassador Marc Thomas in this webinar with a special guest appearance from Franz Walder. It will give you the tools and know-how to stay on top of what is going on with Domino licensing. You will be able lower your cost through an optimized configuration and keep it low going forward.
These topics will be covered
- Reducing license cost by finding and fixing misconfigurations and superfluous accounts
- How do CCB and CCX licenses really work?
- Understanding the DLAU tool and how to best utilize it
- Tips for common problem areas, like team mailboxes, functional/test users, etc
- Practical examples and best practices to implement right away
Building Production Ready Search Pipelines with Spark and MilvusZilliz
Spark is the widely used ETL tool for processing, indexing and ingesting data to serving stack for search. Milvus is the production-ready open-source vector database. In this talk we will show how to use Spark to process unstructured data to extract vector representations, and push the vectors to Milvus vector database for search serving.
Unlock the Future of Search with MongoDB Atlas_ Vector Search Unleashed.pdfMalak Abu Hammad
Discover how MongoDB Atlas and vector search technology can revolutionize your application's search capabilities. This comprehensive presentation covers:
* What is Vector Search?
* Importance and benefits of vector search
* Practical use cases across various industries
* Step-by-step implementation guide
* Live demos with code snippets
* Enhancing LLM capabilities with vector search
* Best practices and optimization strategies
Perfect for developers, AI enthusiasts, and tech leaders. Learn how to leverage MongoDB Atlas to deliver highly relevant, context-aware search results, transforming your data retrieval process. Stay ahead in tech innovation and maximize the potential of your applications.
#MongoDB #VectorSearch #AI #SemanticSearch #TechInnovation #DataScience #LLM #MachineLearning #SearchTechnology
Things to Consider When Choosing a Website Developer for your Website | FODUUFODUU
Choosing the right website developer is crucial for your business. This article covers essential factors to consider, including experience, portfolio, technical skills, communication, pricing, reputation & reviews, cost and budget considerations and post-launch support. Make an informed decision to ensure your website meets your business goals.
Driving Business Innovation: Latest Generative AI Advancements & Success StorySafe Software
Are you ready to revolutionize how you handle data? Join us for a webinar where we’ll bring you up to speed with the latest advancements in Generative AI technology and discover how leveraging FME with tools from giants like Google Gemini, Amazon, and Microsoft OpenAI can supercharge your workflow efficiency.
During the hour, we’ll take you through:
Guest Speaker Segment with Hannah Barrington: Dive into the world of dynamic real estate marketing with Hannah, the Marketing Manager at Workspace Group. Hear firsthand how their team generates engaging descriptions for thousands of office units by integrating diverse data sources—from PDF floorplans to web pages—using FME transformers, like OpenAIVisionConnector and AnthropicVisionConnector. This use case will show you how GenAI can streamline content creation for marketing across the board.
Ollama Use Case: Learn how Scenario Specialist Dmitri Bagh has utilized Ollama within FME to input data, create custom models, and enhance security protocols. This segment will include demos to illustrate the full capabilities of FME in AI-driven processes.
Custom AI Models: Discover how to leverage FME to build personalized AI models using your data. Whether it’s populating a model with local data for added security or integrating public AI tools, find out how FME facilitates a versatile and secure approach to AI.
We’ll wrap up with a live Q&A session where you can engage with our experts on your specific use cases, and learn more about optimizing your data workflows with AI.
This webinar is ideal for professionals seeking to harness the power of AI within their data management systems while ensuring high levels of customization and security. Whether you're a novice or an expert, gain actionable insights and strategies to elevate your data processes. Join us to see how FME and AI can revolutionize how you work with data!
Mind map of terminologies used in context of Generative AI
Nuevos plásticos para un desarrollo sostenible del medio ambiente
1. 1) INTRODUCCION 2) PLASTICOS Y DESARROLLO SOSTENIBLE 2.1) Impacto ambiental 2.2) Producción de matrices plásticas a partir de recursos renovables 3) MATERIALES COMPUESTOS DE BAJO IMPACTO AMBIENTAL 4) MATRICES PARA MATERIALES COMPUESTOS DE BAJO IMPACTO AMBIENTAL 4.1) Almidón y mezclas almidón-acetato de celulosa 4.2) Polilactida (ácido poliláctico, PLA) 5) MATERIALES COMPUESTOS DE BAJO IMPACTO AMBIENTAL CONTENIENDO REFUERZOS OBTENIDOS A PARTIR DE MATERIALES LIGNOCELULÓSICOS 5.1) Objetivos y tipos de pretratamientos 5.2) Propiedades de materiales compuestos constituidos por matrices renovables y refuerzos derivados de materiales lignocelulósicos 6) CONSIDERACIONES FINALES Y CONCLUSIONES 6.1) Aplicaciones y tendencias de mercado 6.2) Perspectivas 7) REFERENCIAS MATERIALES COMPUESTOS DE BAJO IMPACTO AMBIENTAL PRODUCIDOS A PARTIR DE RECURSOS NATURALES
2. 1.- INTRODUCCION Los plásticos tienen naturaleza polimérica. Algunos polímeros naturales (como ámbar, lacas y gutapercha) se conocen desde la antigüedad. El celuloide, obtenido desde el siglo XIX, es un ejemplo de un plástico artificial producido a partir de materias primas naturales (deriva de la celulosa, y se emplea en películas fotográficas). La tecnología del plástico cambió dramáticamente a principios del siglo XX, cuando aparecieron los productos derivados del petróleo, que dominaron el mercado debido a su bajo coste y a su estabilidad química. La II Guerra Mundial produjo un gran aumento de la producción de plásticos, definiendo la situación actual del mercado. Algunos polímeros se producen sintéticamente, mientras que otros (como almidón o celulosa) se encuentran en la naturaleza. Aunque los plásticos se producen a partir de muchos compuestos, el 90% del total se fabrican a partir de cinco polímeros, todos ellos sintéticos. Envases alimentarios Cloruro de polivinilideno (PVDC) CD, gafas, escudos antidisturbios, ventanas seguridad, luces tráfico Policarbonato (PC) Espumas para amortiguación y aislamiento térmicos, recubrimiento de superficies, rodillos de impresión Poliuretanos (PU) Tuberías y canaletas, cortinas de duchas, marcos de ventanas, pavimentos Cloruro de polivinilo (PVC) Fibras, sedal de pesca, moldes para piezas de automóvil Poliamidas (PA) Fibras, materiales textiles Poliéster (PES) Botellas para bebidas carbonatadas, recipientes, películas plásticas, envases para calentamiento por microondas Polietilen-tereftalato (PET) Carcasas de equipos electrónicos Acrilonitrilo-butadieno-estireno (ABS) Capas de recubrimiento en frigoríficos, envases alimentos, vasos desechables Poliestireno de alto impacto (HIPS) Espuma de empaquetado, envases alimentos, vasos desechables, cajas de CD Poliestireno (PS) Envases, apliques, piezas automóvil Polipropileno (PP) Bolsas de supermercado, botellas plásticas Polietileno (PE) Usos habituales Plásticos habituales (nomenclatura)
3. Hoy, la industria de los plásticos es un componente importante de las economías occidentales. Por ejemplo, la industria de los plásicos en USA incluye más de 20.000 fábricas que producen o distribuyen materiales o productos, dando empleo a 1.5 millones de trabajadores y facturando 300.000 millones de dólares por año. Se estima que en el mundo se producen más de 50 millones de toneladas métricas de plásticos por año. Se prevé que el consumo de plástico crezca aproximadamente al 5% por año, hasta alcanzar 250 millones de kg en 2010. En Europa, el consumo de plástico anual por persona es de 60 kg, en comparación con 80 kg en USA. Adicionalmente, en torno al 20% de los residuos urbanos son de naturaleza plástica. De acuerdo con BASF, el consumo de plásticos anual per capita en USA aumentará desde 101 kg en 2001 hasta más de 130 kg en el 2010. Se espera un aumento continuo de la demanda de materiales plásticos en el futuro inmediato . La figura muestra la distribución mundial de la demanda de materiales plásticos (fuente: http://www.fuji-keizai.com/e/report/bio_plastic_e.html)
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6. Estos datos confirman que la producción de plásticos degradables comercialmente competitivos es una cuestión de gran importancia. Los plásticos degradables pueden clasificarse en las categorías siguientes: .Plásticos fotodegradables , que poseen grupos sensibles a la luz directamente incorporados como aditivos en la estructura del polímero. Los plásticos fotodegradables se vuelven débiles y quebradizos cuando se exponen a la luz de sol durante períodos prolongados. Los grupos fotosensibles incluyen di-cetonas, derivados del ferroceno (aminoalquilferroceno) y especies con grupos carbonilo. Estos plásticos se degradan a través de un proceso en dos etapas: inicialmente, la luz ultravioleta rompe algunos enlaces, reduciendo el peso molecular y volviendo quebradizo el plástico; luego, éste se degrada por esfuerzos físicos (como acción de olas o rozamiento contra rocas). La Figura muestra un esquema simplificado de la degradación de polietileno (PE) por peroxidación. .Plásticos semibiodegradables , tales como mezclas de almidón y polietileno. .Plásticos totalmente biodegradables , por ejemplo los constituidos por almidón o poliésteres. PE HC−OOH HC−O • + • OH Calor o esfuerzos mecánicos O 2 Calor o luz ultravioleta
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8. En resumen, el desarrollo de procesos para la producción de plásticos ecológicos biodegradables (plásticos “verdes”) a través de procesos que produzcan un impacto ambiental limitado es una de las líneas de actuación que es preciso emprender. Este tipo de compuestos es hoy una realidad, y la mejora de las tecnologías de procesamiento que se alcancen en un futuro inmediato permitirán aumentar el éxito de este empeño. Como ejemplo, la Figura adjunta muestra los principios generales en que podría basarse un proceso de fabricación de bioplásticos basado en la utilización de biomasa como materia prima. Fraccionamiento Biomasa Agua o disoluciones ácidas monómeros (azúcares) Polímeros (celulosa, almidón) o Hidrólisis y fermentación Bioplásticos (PHA) o monómeros para polimerización (PLA) Producto final Basura Reciclado o compostaje Procesamiento Nutrientes
9. 3) MATERIALES COMPUESTOS DE BAJO IMPACTO AMBIENTAL Los materiales compuestos (“composites”) están constituidos por dos o más materiales con propiedades químicas o físicas significativamene diferentes, que permanecen separados y distinguibles en el producto final. Las propiedades de un determinado material compuesto deben ser distintas de las de sus componentes. En la Biblia, el Éxodo proporciona ejemplos de materiales compuestos primitivos, tales como adobes hechos de paja y barro, o el material de construcción de la cuna de Moisés (hecha de juncos, brea y fango), que podría considerarse como un tipo de material compuesto reforzado con un material fibroso. Los constituyentes de los materiales compuestos son: - la matriz polimérica , que rodea y soporta los materiales de refuerzo, - el refuerzo , que se halla inmerso en la matriz y mejora las propiedades físicas de ésta. Este trabajo se centra en materiales compuestos de bajo impacto ambiental (“environmentally friendly composites”) consitituidos por matrices biodegradables y refuerzos obtenidos a partir de recursos renovables. Estos tipos de materiales suelen denominarse “materiales compuestos ecológicos (“eco-composites”) o “materiales compuestos verdes” (“green composites”). Se presta atención particular al procesamiento por extrusión e inyección por moldeo (técnicas empleadas en el Proyecto NATURPLAS II).
10. 4) MATRICES PARA MATERIALES COMPUESTOS DE BAJO IMPACTO AMBIENTAL Las matrices poliméricas biodegradables que se producen a partir de materias renovables pueden clasificarse en las siguientes categorías: -Matrices sintéticas biodegradables , correspondientes a polímeros presentes en materias primas naturales. Ejemplos típicos de este grupo son el almidón y los polihidroxialcanoatos. -Matrices biosintéticas modificadas , como los derivados de celulosa. Compuestos químicos derivados de la celulosa (por ejemplo, el 2-5 acetato de celulosa, que tiene propiedades termoplásticas y mantiene la biodegradabilidad) abren nuevas rutas para este tipo de aplicaciones. -Polímeros semi-biosintéticos . Las unidades monoméricas se producen de modo natural o por vía fermentativa, y luego se polimerizan por vías sintéticas clásicas. Un ejemplo representativo de este tipo de polímeros el PLA (polilactida/ácido poliláctico). -Polímeros producidos por síntesis química , tipo al que pertenecen los poliésteres. Algunos ejemplos representativos son la policaprolactona (PCL), así como amidas de poliésteres y ésteres del ácido poli-itacónico. Estos compuestos tienen en común el poseer un grupo éster muy reactivo, que desempeña un papel importante en la producción de los materiales compuestos. AMILOSA AMILOPECTINA COMPONENTES DEL ALMIDÓN Enlace (1-4) Enlace (1-6)
11. En la producción de PLA, los isómeros D(-) y L(+) del ácido láctico pueden producirse por fermentación bien como enantiómeros puros o como una mezcla de isómeros, para luego ser polimerizados a PLA. Las propiedades de las matrices citadas pueden mejorarse mezclándolas con determinados componentes. Por ejemplo, mezclas de almidón y acetato de celulosa pueden mejorar las propiedades como matriz termoplástica del almidón puro. Las matrices consideradas en el Proyecto NATURPLAS han sido almidón, mezclas de almidón y acetato de celulosa y PLA. Las secciones siguientes resumen información sobre estas matrices. Ácido L-Láctico Ácido D-Láctico PROPIEDADES DEL ÁCIDO LÁCTICO Nombre químico: Ác. 2-hidroxipropanoico Fórmula química: C 3 H 6 O 3 [50-21-5] L: [79-33-4] Número CAS : D: [10326-41-7] D/L:[598-82-3] L: 53 ºC Punto de fusión D: 53 ºC D/L: 16.8 ºC
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13. Las propiedades negativas pueden contrarrestarse, al menos parcialmente, de los siguientes modos: . Modificando químicamente el almidón (usualmente por esterificación parcial o completa de los grupos hidroxilo de las cadenas laterales) para mejorar su compatibilidad con otros componentes de la formulación. Por ejemplo, se han propuesto tratamientos superficiales del almidón con mónomeros de caprolactona o valerolactona, a fin unir estas moléculas al almidón por medio de enlaces covalentes. Alternativamente, el almidón puede procesarse para “injertar” copolímeros con propiedades termoplásticas (“graft copolymerization”). . Mezclando almidón con otros polímeros , como el acetato de celulosa. Las mezclas de almidón soluble con acetato de celulosa mejoran determinadas propiedades del almidón, como reducción en la afinidad por el agua, resistencia mecánica o disminución de la susceptibilidad a la degradación. Las mezclas conteniendo almidón se biodegradan a velocidades que dependen de la composición y de la cristalinidad. O O O H O H O H O HO O O O H O H HO O O O H O O O H O H O H OH CELULOSA Grupos hidroxilo reactivos que pueden esterificarse por reacción con ácido acético y anhidrido acético en presencia de ácido sulfúrico para dar unidades de anhidroglucosa mono-, di- o tri- sustituidas
14. 4.2 Polilactida (ácido láctico, PLA) El ácido láctico puede producirse a gran escala a través de la fermentación de sueros lácteos, azúcares, materiales amiláceos o sustratos celulósicos (algunos de ellos de origen residual). Algunos residuos típicos que pueden utilizarse para la fabricación de ácido láctico son los desperdicios de la fabricación de patatas fritas o los efluentes de la industrial del queso. La Figura adjunta muestra los pasos involucrados en la producción de ácido láctico a partir de almidón. Como se explicó anteriormente, dependiendo de la tecnología empleada y de las condiciones experimentales, la fermentación puede conducir a la producción de mezlcas de isómeros de ácido láctico [D(-) y L(+)] o a isómeros puros. El ácido L-láctico puro tiene un precio de mercado casi 3 veces mayor que las mezclas de isómeros D(-) y L(+). Almidón Dextrosa (sin refinar) Fermentación Producción de monómeros Producción de polímero Ácido poliláctico Modificación para clientes Aplicaciones Ácido láctico Lactida
15. Debido a la naturaleza quiral del ácido láctico existen dos lactidas: .Poli-DL-lactida (PDLLA), obtenida por polimerización de una mezcla rácémica del L- y D- lactidas, de caracter amorfo, que puede degradarse rápidamente. .Poli-L-lactida (PLLA), que resulta de la polimerización de la L,L-lactida (también denominada L-lactida), que tiene una cristalinidad en torno al 37%, una temperatura de transición vítrea entre 50 y 80 ºC y una temperatura de fusión de 173-178 ºC. La PLLA funde a 170-180 ºC, y tiene un punto de reblandecimiento de 58 ºC, una resistencia a la tracción de 700 kg/cm y una transparencia del 94%. Puede procesarse en películas de espesores entre 10 y 500 μ m de espesor, y admite procesamiento de moldeo por inyección. La PLLA es usualmente dura y quebradiza. Los progresos en biotecnología han permitido ell desarrollo de procesos comerciales para la producción de D-LA (por PURAC), permitiendo la producción de poli-D-lactida ( PDLA), que se mezcla generalmente con PLLA para mejorar las propiedades mecánicas, debido a la fuerte interacción entre las cadenas de PLLA y PDLA. Así, los estereocomplejos de mezclas PLLA/PDLA tienen una temperatura de fusión de 220–230 ºC, del orden de 50 ºC más altas que las de PLLA y PDLA. LD-lactida LL-lactida
16. Las tecnologías de reacción citadas anteriormente permiten la obtención de una extensa gama de productos de diferente peso molecular y cristalinidad, que resultan útiles para distintos tipos de aplicaciones. El PLA se produce habitualmente por polimerización a través de la apertura del anillo de la lactida (véase Figura) en medios catalizados. El brillante futuro del PLA lo coloca al frente de las industrias emergentes de los plásticos biodegradables. Algunas compañías que producen PLA son: -NatureWorks LLC (una filial de Cargill Corporation, U. S. A.) -Toray Industries Inc. (Japón) -Galactic (Bélgica) -PURAC (una filial de CSM, Países Bajos) Catalizador, calor Lactida Polilactida Polimerización de lactida a polilactida
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19. Los términos “materiales compuestos de bajo impacto ambiental”,“materiales compuestos ecológicos” o “materiales compuestos verdes” se emplean habitualmente para describir los materiales compuestos que presentan ventajas ambientales y ecológicas respecto a los convencionales. En este trabajo, la atención se ha centrado en materiales compuestos que contienen las matrices poliméricas biodegradables que se han descrito en secciones previas, así como refuerzos derivados de materiales lignocelulósicos. La Figura adjunta ilustra la estructura de un sustrato lignocelulósico típico. 5) MATERIALES COMPUESTOS DE BAJO IMPACTO AMBIENTAL CONTENIENDO REFUERZOS OBTENIDOS A PARTIR DE MATERIALES LIGNOCELULÓSICOS Lignina Hemicelulosas Celulosa Célula vegetal Pared de la célula
20. El introducir refuerzos derivados de materiales lignocelulósicos en matrices plásticas permite una serie de mejoras, incluyendo: .Reemplazar productos químicos caros por productos naturales baratos .Mejorar las propiedades tecnológicas .Obtener un beneficio ambiental, derivado del carácter renovable y biodegradable de los refuerzos. .Obtener mejoras sociales y económicas, que surgen del aumento esperado de la demanda. La Figura adjunta muestra algunas fuentes típicas de materiales lignocelulósicos .Bosques (>60% del total de generación de materiales lignocelulósicos) .Agricultura (pajas, hierbas, subproductos agrícolas) .Otros (plantas y hierbas que crecen en tierras improductivas, etc.). .Industria, particularmente subproductos o residuos sólidos (bagazo, serrín, etc.) .Residuos sólidos urbanos (papel de periódico y papeles usados, cartones) Fuentes primarias (materias primas nativas) Fuentes secundarias (materias primas procesadas) FUENTES DE MATERIALES LIGNOCELULÓSICOS
21. Los materiales lignocelulósicos son heterogéneos, y poseen una naturaleza química compleja. Sus componentes puede clasificarse como sigue: .Componentes estructurales , de naturaleza polimérica, que incluyen: ..Celulosa, un homopolímero constituido por unidades de beta-glucosa, con estructura parcialmente cristalina y notable resistencia mecánica. ..Hemicelulosas, un heteropolímero que puede estar constituido por distintos azúcares (glucosa, manosa, xilosa, galactosa, arabinosa) y sustituyentes (como grupos urónicos, grupos fenólicos esterificados y grupos acetilo). ..Lignina, un polímero amorfo constituido por unidades fenil-propano. .Constituyentes no estructurales , que incluyen extractos, cenizas y proteínas. En los materiales lignocelulósicos nativos, la celulosa se halla inmersa en una matriz de lignina y hemicelulosas. El contenido en celulosa de los materiales lignocelulósicos depende de la materia prima considerada, yendo desde el 45% en madera resinosas hasta más del 70% en hojas fibrosas. Estructura del xilano, un polímero hemicelulósico típico OH OR O O O O H O H O H O O O O O H OH R O OH OH
22. Se han empleado como refuerzos para materiales compuestos tanto lignocelulósicos nativos como procesados. Se han publicado estudios sobre materiales compuestos reforzados con materiales celulósicos obtenidos a partir de: .Maderas , incluyendo pino, haya, abeto y eucalipto. .Pasta de celulosa procedentes de factorías kraft, incluyendo fibras residuales. .Distintos materiales naturales distintos de las maderas , como bambú, fibra de coco, algodón, sisal, cáñamo, lino, yute, esparto, cáscaras, ramio, palmas, bananas, zuros de maíz, hierbas y pajas. .Subproductos industriales y residuos de las industrias alimentarias (como el bagazo), instalaciones de industrias textiles, etc. .Residuos urbanos de naturaleza celulósica , como papel usado y cartones. Los materiales de refuerzo obtenidos a partir de materiales lignocelulósicos corresponden al tipo de “fibras duras”, y que incluyen a las fibras obtenidas de hojas y de maderas. Pinus pinaster , el pino más común en el Noroeste de la Península Ibérica Eucalyptus globulus , el eucalipto más común en el Noroeste de la Península Ibérica
23. Los efectos de refuerzo causados por materiales derivados de materias primas de naturaleza celulósica dependen de distintos factores, incluyendo: .El origen y la naturaleza del material considerado (tipo, edad, condiciones de crecimiento…), que determinan la estructura interna y la composición de las fibras. .El grado de polimerización de la celulosa , el tamaño de fibra y la distribución de tamaños de las fibras (usualmente, las fibras de mayor longitud permiten mayores efectos de refuerzo). .La relación de aspecto (“aspect ratio”), o cociente entre longitud y diámetro. Las fibras con mayor relación de aspecto suelen mejorar la resistencia y las propiedades de tracción. .El contenido en fibra de los materiales compuestos, .Las alteraciones en las fibras causadas por tratamientos físicos y químicos, .La compatibilidad interfacial entre la matriz y los refuerzos. La Figura adjunta muestra otras ventajas de los refuerzos derivados de materiales lignocelulósicos -Carácter renovable -Posibilidad de producción a partir de residuos -Biodegradabilidad -No contribuye a las emisiones de CO 2 -Producción limitada de cenizas -Gran disponibilidad -Geográficamente dispersos -Menor coste que las matrices plásticas -Menor coste que otros refuerzos -Buenas propiedades mecánicas específicas -Alta resistencia -Area superficial relativamente reactiva -Posibilidad de funcionalización -Facilidad de procesamiento (alta flexibilidad, naturaleza no abrasiva) -Buena resistencia química -Baja densidad aparente -Buena capacidad de aislamiento acústico -Procesabilidad por distintas tecnologías (incluyendo moldeo por inyección) Económicas y prácticas Ambientales Ventajas de los refuerzos derivados de materiales lignocelulósicos Tecnológicas
24. Alternativamene, algunos de los inconvenientes de los refuerzos derivados de materiales lignocelulósicos son: .Adhesión interfacial inadecuada .Elevado carácter hidrófilo .Escasa resistencia a la humedad .Estabilidad térmica limitada (no se recomiendan temperaturas mayores de 175 ºC durante tiempos de procesamiento prolongados) Estas desventajas pueden paliarse (al menos parcialmente) de las siguientes formas: .Utilizando matrices plásticas polares .Modificando las fibras por procedimientos químico-fisicos a fin de: .. Obtener mejor compatibilidad interfacial, mejando el anclaje entre matriz y refuerzo. .. Aumentar el tamaño de poro y la rugosidad de la superficie, lo que redunda en la mejora de las propiedades mecánicas.
25. 5.1 Objetivos y tipos de pretratamientos Cuando se pretende obtener un refuerzo basado en fibras de celulosa para materiales compuestos a partir de un determinado material lignocelulósico, el principal objetivo de los tratamientos químicos a implementar es eliminar fracciones no-celulósicas. Esta estrategia puede implicar: -La eliminación de componentes no estructurales (extractos, ceras). -La eliminación de los componentes estructurales distintos de la celulosa (lignina y hemicelulosas), a fin de aumentar el contenido del sustrato en celulosa, ya que es ésta quien proporciona los efectos de refuerzo que se buscan. La Tabla adjunta presenta datos sobre las propiedades de fibras celulósicas procedentes de distintas materias primas. 11 1720 0.5 379 2020 Carbono alta resistencia 8.2 2550 1.3 200 1820 Carbono 11.9 2760 2.5 124 1440 Aramid (K49) 4580 4.6 85 2500 Vidrio (S) 3400 3.4 71 2550 Vidrio (E) 840 1.8 100 1520 Lino 920 1.7 70 1520 Cáñamo 200 860 2.0 60 1520 Yute 20-80 413-1627 1.6 35-82 1440 Piña 50-300 530-640 3-7 10-22 1450 Sisal 25-40 980 1500 Abacá 200-800 6-12 27 1520 Algodón 100-450 131-175 15-40 4-6 1150 Coco (cáscara) Diámetro μm Resistencia MPa Elongación % Módulo GPa Densidad kg/m 3 Fibras naturales Fibras artificiales Propiedades de las fibras
26. En relación con los tratamientos poco agresivos, la bibliografía ha considerado tanto el procesamiento acuoso como el procesamiento alcalino. El procesamiento acuoso incluye: - autohidrólisis (con agua caliente comprimida) para eliminar extractos, extraer materiales tipo cera y solubilizar las hemicelulosas, que se convierten en oligómeros solubles - explosión con vapor (“steam explosion”), que además altera la estructura del sustrato, provocando la rotura de las paredes celulares y liberando la celulosa de la matriz lignocelulósica. La oxidación húmeda (“wet oxidation”) es una tecnología relacionada con las anteriores, en que se añade oxígeno al medio acuoso en que se procesa la materia prima para facilitar la descomposición de la lignina y de las hemicelulosas. Equipamiento de explosión con vapor (source: http://www.biogasol.dk/2me2.htm)
27. En función de las condiciones de operación, los tratamientos alcalinos pueden causar distintos efectos sobre los materiales lignocelulósicos nativos, incluyendo: .eliminación de extractos, ceras y otros materiales no estructurales .conversión de los haces de fibras de celulosa en otros de menor tamaño y en fibras aisladas .hinchamiento , con reducción de la intensidad de los enlaces de hidrógeno en la red celulósica .reducción del diámetro de la fibra, con aumento de la relación de aspecto . aumento del área accesible , con una topografía rugosa, que favorece la interpenetración .alteración de las propiedades fisicoquímicas de la celulosa (reducción de cristalinidad y grado de polimerización), .modificación de la orientación de las zonas cristalinas de la celulosa .aumento de la facilidad de mojado , mejorando la reactividad .eliminación de los componentes poliméricos no celulósicos de la pared vegetal (celulosa, lignina) Algunos procesos de pasteo suponen un caso extremo de tratamiento alcalino, donde el objetivo principal es eliminar la lignina. Esto puede conseguirse empleando NaOH (proceso a la sosa) o mezclas NaOH/Na 2 S (proceso kraft). Las fibras kraft y los sustratos que las contienen (como papel de periódico o cartones) se han empleado como refuerzos para materiales compuestos. Alternativamente, los tratamientos alcalinos en condiciones suaves pueden llevarse a cabo en presencia de compuestos oxidantes (como H 2 O 2 ). Esta estrategia permite una deslignificación selectiva (debido a la susceptibilidad de la lignina a reacciones de oxidación), y puede emplearse para que las fibras de celulosa que se encuentran en la superficie del material lignocelulósico se vuelvan accesibles a los reactivos químicos o a las matrices plásticas.
28. Una posibilidad alternativa es llevar a cabo distintos tratamientos para modificar las propiedades de las fibras naturales (por ejemplo, su carácter hidrófilo, lo que reduciría los efectos de la humedad sobre el material compuesto y mejoraría la compatibilidad interfacial). Como ejemplo, la Figura muestra el esquema de la reacción de carboximetilación de la celulosa, que puede emplearse para introducir grupos carbonilo. CARBOXIMETILCELULOSA (Sustitución en C 6 ≥ Sustitución en C 2 >> Sustitución en C 3 Monosubstituted unit Isopropanol - ClH 2 C-COOH 1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6 n C H 2 C O O - O H O H H H H H O O H O O H O H H H H O O H O H O H O H H H H H O O O O H O H H H H H O H O C H 2 C O O - C H 2 C O O - C H 2 C O O - C H 2 C O O - 1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6 O H O H H H H H O O H O H O H O H H H H H O O H O H O H O H H H H H O O H O H O H O H H H H H O H O H n Disubstituted unit CELULOSA
29. Los agentes químicos empleados para la modificación de fibras celulósicas deben enlazarse a éstas de forma covalente, a fin de cambiar sus propiedades. Las reacciones de modificación química de la celulosa deben cumplir distintas condiciones, como: .deben transcurrir a pH moderado (medio neutro o débilmente ácido/alcalino) .la cinética debe ser suficientemente rápida para asegurar una conversión razonable cuando se opere en condiciones de utilidad práctica, .deben evitarse temperaturas superiores a 150 ºC , a fin de evitar reacciones de degradación .los derivados deben ser estables .los reactivos deben poder penetrar en la red celulósica , lo que puede exigir el hinchamiento de la celulosa .las propiedades tecnológicas del derivado (color, características mecánicas, estabilidad térmica, sensibilidad hacia la humedad) deben ser iguales o mejores que las del sustrato sin derivar. Además, la derivación debe ser económica para asegurar la viabilidad práctica de la reacción considerada. La bibliografía ha propuesto distintas alternativas para la obtención de derivados, incluyendo acetilación, cianoetilación, blanqueo, tratamientos con silano, benzoilación, tratamientos con peróxido e isocianato, acrilación, recubrimiento con látex, etc. De modo adicional o alternativo, la matriz plástica puede modificarse para mejorar su compatibilidad con los refuerzos de naturaleza celulósica.
30. La copolimerización (“graft copolymerization”) y la inserción de grupos de acoplamiento (“coupling groups”) son formas usuales de llevar a cabo las reacciones de derivación de la celulosa. La copolimerización se ha empleado para unir polietileno a las fibras celulósicas en una reacción inducida por peróxido, mientras que se han empleado como grupos de acoplamiento el silano, anhidrido maleico, titanato y triazima. Introducción de un monómero (M) en cadenas de celulosa y celulosa acetilada a) Formación del radical de la macromolécula b) Unión del monómero Inicio Propagación Terminación Inserción de un agente de acoplamiento H 2 N R Fibra celulósica Fibra celulósica
31. 5.2) Propiedades de materiales compuestos constituidos por matrices renovables y refuerzos derivados de materiales lignocelulósicos Los materiales compuestos reforzados con fibras naturales proporcionan una alternativa única a los materiales compuestos convencionales formados por polipropileno o poliésteres insaturados reforzados con fibra de vidrio, admitiendo una amplia diversidad de aplicaciones prácticas. Los materiales compuestos formados por a lmidón reforzado con fibras de celulosa son un ejemplo típico de un material compuesto formado por polímeros naturales, presentando ventajas como su naturaleza renovable, carácter biodegradable, abundancia y bajo coste. En la bibliografía se ha propuesto emplear como refuerzos del almidón una serie de materiales celulósicos como sisal, algodón, bambú, yute, pajas, kenaf, madera y pasta kraft. Al igual que muchos otros materiales compuestos reforzados con fibras, el objetivo prinicpal de introducir refuerzos celulósicos en matrices de almidón es la mejora de las propiedades mecánicas. Así, el almidón termoplástico reforzado presenta hasta cuatro veces mejores propiedades mecánicas que la matriz sin reforzar. En materiales compuestos a base de almidón conteniendo fibras de lino en disposición unidireccional y cruzada, obtenidas por prensado en caliente por el procedimiento de apilamiento de capas, las propiedades mecánicas dependen del contenido en fibras y de la disposición de éstas. La resistencia a la tracción aumenta con el contenido en fibras (hasta el 40%). En el mejor caso, la resistencia a la tracción del material compuesto fue tres veces mayor que el de la matriz de almidón puro, mientras que la presencia de fibras aumentó el módulo en varios órdenes de magnitud. La Sección 7 presenta referencias sobre este tipo de materiales compuestos. Los materiales compuestos reforzados con acetato de celulosa son otra de las alternativas consideradas en la bibliografía. Estos materiales compuestos son biocompatibles, lo que permite aplicaciones de tipo biológico. Algunos trabajos publicados sobre este tema han examinado aspectos como citotoxicidad, adhesión celular y estabilidad térmica, así como la aplicación de técnicas experimentales que evitan etapas de procesamiento termomecánico (que podrían ocasional una degradación prematura de las fibras). Las mezclas de almidón y acetato de celulosa presentan mejoras de propiedades en el intervalo 52-64%. En el caso de materiales compuestos almidón-acetato de celulosa-fibras de celulosa, los productos presentan una ductilidad reducida en comparación con la matriz sin reforzar. La Sección 7 presenta referencias sobre este tipo de materiales compuestos.
32. El PLA es un polímero que puede establecer un nuevo modelo de desarrollo industrial, ya que los países desarrollados son totalmente dependendientes de los recursos fósiles para obtener los combustibles, polímeros y productos químicos que se necesitan en el mundo actual. Los expertos y analistas han concluido que las nuevas materias primas jugarán un papel significativo en un mundo que se halla ante el reto de los problemas interrelacionados del agotamiento de los recursos fósiles y de los aumentos de las emisiones con efecto invernadero, de los agentes contaminantes y de los residuos sólidos. En este contexto, el PLA presenta propiedades mecánicas comparables a las de los termoplásticos tradicionales, y puede fabricase a partir de materias primas que contengan polisacáridos (incluyendo tanto materiales amiláceos como lignocelulósicos). En base a las ideas anteriores, la “sostenibilidad” del PLA puede contemplarse desde distintos puntos de vista: . Sostenibilidad económica , como un negocio rentable, capaz de producir beneficios a lo largo de la cadena de valor (incluyendo nuevos mercados para los productos agrícolas, nuevas oportunidades profesionales para científicos y tecnólogos, y otros beneficios económicos a los inversores y a la sociedad). .Sostenibilidad ambiental , relacionada con la producción de bienes útiles, que pueden desarrollar funciones positivas en el mercado y en la sociedad, con menor impacto ambiental que las alternativas empleadas hoy en día. .Sostenibilidad social , que se traduce en responsabilidad social, e incluye conceptos como igualdad de oportunidades para todos los agentes involucrados en la cadena de valor. Todas estas ideas puede aplicarse (e incluso ampliarse) a los materiales compuestos conteniendo refuerzos lignocelulósicos. Estos materiales compuestos abren el camino a la nueva generación de materiales, productos y procesos sostenibles, con bajo impacto ambiental y altamente eco-eficientes. Este tipo de materiales compuestos se han citado como uno de los productos más atrayentes del siglo XXI, constituyendo una alternativa ventajosa siempre que las propiedades puedan mejorarse manteniendo los costes suficientemente bajos y conservando la biodegradabilidad.
33. Uno de los factores cruciales que deben considerarse en el reforzamiento de materiales compuestos con fibras celulósicas es la proporción de éstas. Usualmente, la resistencia aumenta con el contenido en refuerzo hasta un valor umbral, que depende del caso estudiado. Se han citado valores de contenido en refuerzo de hasta un 50%, si bien el grado de reemplazamiento más habitual está en torno al 30%. De hecho, contenidos en fibras mayores de este límite suelen conducir a mezclas muy viscosas, que resultan difíciles de procesar en equipos convencionales de moldeo por inyección. En los ensayos de tracción, se espera que el módulo de los materiales compuestos conteniendo PLA y refuerzos celulósicos aumente significativamente respecto a la matriz pura de PLA, mientras que la resistencia debe variar poco, y la elongación se reduce. Por otra parte, la presencia de los refuerzos celulósicos en matrices de PLA suele provocar un empeoramiento a la resistencia al impacto, ya que este parámetro depende estrechamento de la adhesión entre matriz polimérica y refuerzo. Como en otros materiales compuestos, la interfase PLA-refuerzo juega un papel crítico a la hora de asegurar que las propiedades de cada componente contribuyen óptimamente a las propiedades del producto final. La adhesión interfacial se ve afectada por distintos factores, entre los que se encuentran la naturaleza de las interfases, las condiciones de operación (que pueden originar degradación térmica) y cambios químicos superficiales que pueden perjudicar las propiedades globales. La Sección 7 muestra información sobre propiedades de materiales compuestos a base de PLA.
34. 6) CONSIDERACIONES FINALES Y CONCLUSIONES La sostenibilidad de un determinado producto o proceso debe evaluarse utilizando los métodos adecuados. Con este fin, la “International Standards Organization” (ISO) ha venido desarrollando desde 1993 programas de análisis de ciclos de vida (“Life Cycle Assessment”, LCA) que proporcionan las herramientas necesarias para hacer un análisis e inventario de los aportes y excedentes de materiales y energía (“input/output”) asociados a un determinado producto. La primera iniciativa en el desarrollo del análisis de ciclo de vida fue establecer líneas de actuación para los próximos años que definiesen cómo desarrollar y difundir herramientas prácticas para evaluar las oportunidades, riesgos e intercambios asociados a productos y servicios a lo largo de todo su ciclo de vida, de cara a alcanzar un desarrollo sostenible. A través del análisis de ciclo de vida resulta posible comparar los impactos ambientales de varios plásticos “verdes” entre sí y con poliolefinas convencionales (que suponen más del 90% de la producción actual de plásticos).
35. En comparación con los polímeros de almidón, los beneficios ambientales derivados de la utilización de PLA (que representa el 10-15% de la producción de plásticos “verdes”) o de la utilización de polímeros biodegradables producidos a partir de fuentes no renovables (que suponen aproximadamente el 10% del total), parecen ser menores, aunque conservan ventaja sobre los polímeros tradicionales. Para los poliésteres de origen microbiano, la ventaja ambiental (de existir) parece pequeña, pero las tecnologías de producción fermentativa se han desarrollado recientemente, y tanto el método como la escala de producción pueden afectar a las evaluaciones de los efectos ambientales globales. T.U. Gerngross y S.C.Slater han publicado un análisis de ciclo de vida (“How Green Are Green Plastics?” Scientific American, August 2000) que ha recibido mucha atención, pero su estudio se enfoca únicamente hacia los poliésteres microbianos, por lo que su trabajo responde mejor a la pregunta “hasta qué punto son verdes los poliésteres microbianos?”). Para analizar el efecto (o el impacto) de un determinado producto en el ambiente, han de considerarse los distintos aspectos mostrados en la Figura adjunta. Aunque el análisis de ciclo de vida de los plásticos está todavía en sus etapas iniciales de desarrollo, comienzan a aparecer determinadas tendencias. Una revisión de 20 estudios de análisis de ciclo de vida de polímeros biodegradables (M. Patel, presentación en la “7th World Conference on Biodegradable Polymers and Plastics”, Pisa, Italia, Junio 2002) indica que el almidón, el mayor componente de aproximadamente el 75% de los “plásticos verdes”, ofrece importantes beneficios ambientales en comparación con polímeros convencionales. Extracción de materias primas Procesos Reciclado de productos Vertedero Utilización de productos
36. 6.1) Aplicaciones y tendencias de mercado El número de aplicaciones de los plásticos biodegradables y materiales compuestos está aumentando enormemente. Esta tendencia está impulsada por las tecnologías modernas, que proporcionan herramientas poderosas para determinar microestructuras a diferentes niveles, y para comprender las relaciones entre estructuras y propiedades. Estos nuevos niveles de comprensión proporcionan oportunidades para desarrollar materiales para nuevas aplicaciones. El PLA es un ejemplo representativo en este campo. La Figura adjunta muestra un diagrama que muestra el amplio campo que abarcan las aplicaciones genéricas del PLA
37. En otros lugares de esta web puede encontarse más información sobre aplicaciones de materiales compuestos en la industria del automóvil, muebles, etc. Como ejemplos representativos de desarrollos recientes, la Tabla adjunta lista aplicaciones propuestas para un PLA comercial (NatureWorksTM). Tipo de negocio Aplicaciones – Recipientes para frutas frescas y vegetales – Bandejas para alimentos -Termoformados rígidos – Envases opacos (yogures) – Contenedores para panadería, hierbas frescas y caramelos – Embalajes de pantallas y material electrónico – Materiales desechables y vasos para bebidas frías – Envoltorios enrollables (caramelos) – Cajas para envoltorio y material de embalaje transparente – Películas laminadas – Exhibidores de regalos -Películas con – Tapas para mercancías situadas en exhibidores orientación biaxial – Cuños para etiquetado – Envoltorios para flores – Cintas – Bolsas capaces de sostenerse – Bolsas para tartas, cereales y pan – Leche de consumo rápido -Botellas – Aceites comestibles – Agua embotellada
38. 6.2 Perspectivas El brillante futuro de los plásticos verdes y de los correspondientes materiales compuestos se basa en tres pilares: nuevos materiales, nuevos procesos y nuevos productos (o aplicaciones). Por ejemplo, en el caso del PLA, el producto obtenido a partir de almidón (también llamado PLA1) se espera que sea reemplazado por el PLA de segunda generación (denominado PLA2), basado en la lignocelulosa. En este caso, se espera que las materias primas sean residuos de cosechas (tallos, paja, cáscaras y hojas), y que tanto la celulosa como las hemicelulosas se conviertan en azúcares para fermentación en las llamadas “bio-refinerías”. La fracción residual, rica en lignina, puede quemarse o gasificarse para producir vapor, que suministraría energía para los distintos procesos de conversión. El concepto de bio-refinería hace máximo el valor añadido de las materias primas lignocelulósicas, obteniendo distintos productos, valorizando subproductos y co-productos, mejorando el balance producción/consumo de energía y optimizando recursos y excedentes, incluyendo el tratamiento de residuos. En relación con la producción de ácido láctico, el proceso se adaptará para permitir la utilización de azúcares derivados de materiales lignocelulósicos, y se optimizará para reducir el consumo de materias primas, entre otras mejoras. Fibra de vidrio Polímeros proced. petróleo HOY MAÑANA Nanofibras celulósicas Bio-polímeros Componentes moldeados Componentes moldeados
39. Las nuevas tecnologías de producción de materiales compuestos abarcan la utilización de nano-refuerzos, que pueden permitir grandes mejoras en las propiedades mecánicas con bajos grados de reemplazamiento. Este tipo de refuerzos es particularmente importante para polímeros obtenidos a partir de fuentes renovables, dado que en su mayor parte tienen como desventajas sus bajas temperaturas de reblandecimiento y módulos. Los materiales compuestos a base de PLA y nano-refuerzos de naturaleza celulósica constituyen un ejemplo representativo de productos con bajo impacto ecológico. Su desarrollo y utilización a gran escala dependerá del coste de los nano-refuerzos, que debe ser competitivo con los de otras alternativas existentes en el mercado. La Sección 7 incluye una lista de referencias que trata de materiales compuestos conteniendo nano-refuerzos.
40. 7) REFERENCIAS 7.1) Referencias con información general sobre materiales compuestos reforzados con fibras naturales 7.2) Referencias sobre materiales compuestos a base de almidón y/o acetato de celulosa 7.3) Referencias sobre materiales compuestos a base de PLA 7.4) Referencias sobre la utilización de sustratos celulósicos (nativos, pretratados o sometidos a modificación química) para la producción de materiales compuestos 7.5) Referencias sobre la biodegradabilidad/compostaje/análisis de ciclo de vida de matrices plásticas y materiales compuestos
41. Bismarck, Alexander; Mishra, Supriya; Lampke, Thomas.Plant fibers as reinforcement for green composites. Mohanty, Amar K.; Misra, Manjusri; Drzal, Lawrence T. Natural Fibers, Biopolymers, and Biocomposites (2005), 37-108. A review discussing the variety, structure and mech. properties of plant fibers and advantages of their use as reinforcement for plastics. The bast fibers (flax, kenaf, nettle, hemp, jute, ramie), leaf fibers (sisal, henequen, pineapple, abaca, oil palm), seed fibers (cotton), fruit fibers (coconut husk or coir), and stalk fibers (cereal straw) are considered. The increasing environmental awareness, growing global waste problems, and continuously rising high crude oil prices motivate development of the environmentally and economically viable materials using renewable resources. Composites with moderate strength can be used in many noncrit. structural applications in automotive, electronic, packaging, and building industries. Green composites made entirely from renewable agricultural resources offer a unique alternative to the commonly used synthetic reinforcing fibers, such as carbon, glass or aramid, because of their low d., good mech. properties, abundance, and easy recycling. Some drawbacks related to the use of plant fibers as reinforcement for polymers are high moisture absorption, low microbial resistance, and low thermal stability. Bledzki, A. K.; Gassan, J. Composites reinforced with cellulose based fibres. Progress in Polymer Science (1999), 24(2), 221-274. This review article, with refs., concerning natural and man-made cellulose fiber-reinforced plastics, introduces possible applications of this material group. The phys. properties of natural fibers are mainly detd. by the chem. and phys. compn., such as the structure of fibers, cellulose content, angle of fibrils, cross-section, and by the d.p. Only a few characteristic values, but esp. the specific mech. properties, can reach comparable values of traditional reinforcing fibers. This phys. structure can be modified by using alkali treatment and acetylation processes. The application of natural fibers as reinforcements in composite materials requires, just as for glass-fiber reinforced composites, a strong adhesion between the fiber and the matrix, regardless of whether a traditional polymer (thermoplastics or thermosets) matrix, a biodegradable polymer matrix or cement is used. Further this article gives a survey about phys. and chem. treatment methods which improve the fiber matrix adhesion, their results and effects on the phys. properties of composites. These different treatments change among others the hydrophilic character of the natural fibers, so that moisture effects in the composite are reduced. To bring about hydrophobic properties to natural fibers, a special treatment, termed acetylation, can be used. The effectiveness of this method is strongly influenced by the treatment conditions used. The mech. and other phys. properties of the composite are generally dependent on the fiber content, which also dets. the possible amt. of coupling agents in the composite. The influence of such treatments by taking into account fiber content on the creep, quasi-static, cyclic dynamic and impact behavior of natural fiber-reinforced plastics are discussed in detail. For special performance requirements, hybrid composites made of natural and conventional fibers can be prepd. with desired properties. The processing conditions play, next to the mech. properties of natural fibers, an important role for the industrial use of these materials. Natural fibers seem to have little resistance towards environmental influences. This can be recognized in the composite and can be advantageously utilized for the development of biol. degradable composites with good phys. properties. Eichhorn, S. J.; Baillie, C. A.; Zafeiropoulos, N.; Mwaikambo, L. Y.; Ansell, M. P.; Dufresne, A.; Entwistle, K. M.; Herrera-Franco, P. J.; Escamilla, G. C.; Groom, L.; Hughes, M.; Hill, C.; Rials, T. G.; Wild, P. M. Current international research into cellulosic fibers and composites. Journal of Materials Science (2001), 36(9), 2107-2131. The following paper reviews with 101 refs a no. of international research projects being undertaken to understand the mech. properties of natural cellulose fibers and composite materials. In particular the use of novel techniques, such as Raman spectroscopy, synchrotron x-ray and half-fringe photoelastic methods of measuring the phys. and micromech. properties of cellulose fibers is reported. Current single fiber testing procedures are also reviewed with emphasis on the end-use in papermaking. The techniques involved in chem. modifying fibers to improve interfacial adhesion in composites are also reviewed, and the use of novel fiber sources such as bacterial and animal cellulose. It is found that there is overlap in current international research into this area, and that there are complementary approaches and therefore further combining of these may make further progress possible. In particular a need to measure locally the adhesion properties and deformation processes of fibers in composites, with different chem. treatments, ought to be a focus of future research. 7.1) Referencias con información general sobre materiales compuestos reforzados con fibras naturales
42. Garlotta, Donald. A literature review of poly(lactic acid). Journal of Polymers and the Environment (2002), Volume Date 2001, 9(2), 63-84. A literature review is presented regarding the synthesis and physicochem., chem., and mech. properties of poly(lactic acid) (PLA). PLA exists as a polymeric helix, with an orthorhombic unit cell. The tensile properties of PLA can vary widely, depending on whether or not it is annealed or oriented or what its degree of crystallinity is. Also discussed are the effects of processing on PLA. Crystn. and crystn. kinetics are examd. Soln. and melt rheol. is also discussed. Four different power-law equations and 14 different Mark-Houwink equations are presented. NMR, UV-visible, and FTIR spectroscopy of PLA are briefly discussed. Finally, research conducted on starch-PLA composites is introduced. Mohanty, A. K.; Misra, M. Studies on jute composites - A literature review. Polymer-Plastics Technology and Engineering (1995), 34(5), 729-92. A review with 327 refs. on the title material. Mohanty, A. K.; Misra, M.; Drzal, L. T. Sustainable Bio-Composites from Renewable Resources: Opportunities and Challenges in the Green Materials World. Journal of Polymers and the Environment (2002), 10(1/2), 19-26. A review. Sustainability, industrial ecol., eco-efficiency, and green chem. are guiding the development of the next generation of materials, products, and processes. Biodegradable plastics and bio-based polymer products based on annually renewable agricultural and biomass feedstock can form the basis for a portfolio of sustainable, eco-efficient products that can compete and capture markets currently dominated by products based exclusively on petroleum feedstock. Natural/Biofiber composites (Bio-Composites) are emerging as a viable alternative to glass fiber reinforced composites esp. in automotive and building product applications. The combination of biofibers such as kenaf, hemp, flax, jute, henequen, pineapple leaf fiber, and sisal with polymer matrixes from both nonrenewable and renewable resources to produce composite materials that are competitive with synthetic composites requires special attention, i.e., biofiber-matrix interface and novel processing. Natural fiber-reinforced polypropylene composites have attained com. attraction in automotive industries. Natural fiber-polypropylene or natural fiber-polyester composites are not sufficiently eco-friendly because of the petroleum-based source and the nonbiodegradable nature of the polymer matrix. Using natural fibers with polymers based on renewable resources will allow many environmental issues to be solved. By embedding biofibers with renewable resource-based biopolymers such as cellulosic plastics; polylactides; starch plastics; polyhydroxyalkanoates (bacterial polyesters); and soy-based plastics, the so-called green bio-composites are continuously being developed. Saheb, D. Nabi; Jog, J. P. Natural fiber polymer composites: A review. Advances in Polymer Technology (1999), 18(4), 351-363. A review with 115 refs.; natural fiber-reinforced composites is an emerging area in polymer science. These natural fibers are low-cost fibers with low d. and high specific properties. These are biodegradable and non-abrasive. The natural fiber composites offer specific properties comparable to those of conventional fiber composites. However, in development of these composites, the incompatibility of the fibers and poor resistance to moisture often reduce the potential of natural fibers and these drawbacks become crit. issue. This review presents the reported work on natural fiber-reinforced composites with special ref. to the type of fibers, matrix polymers, treatment of fibers and fiber-matrix interface. Yu, Long; Dean, Katherine; Li, Lin. Polymer blends and composites from renewable resources. Progress in Polymer Science (2006), 31(6), 576-602. A review. This article reviews recent advances in polymer blends and composites from renewable resources, and introduces a no. of potential applications for this material class. In order to overcome disadvantages such as poor mech. properties of polymers from renewable resources, or to offset the high price of synthetic biodegradable polymers, various blends and composites have been developed over the last decade. The progress of blends from three kinds of polymers from renewable resources-(1) natural polymers, such as starch, protein and cellulose; (2) synthetic polymers from natural monomers, such as polylactic acid; and (3) polymers from microbial fermn., such as polyhydroxybutyrate-are described with an emphasis on potential applications. The hydrophilic character of natural polymers has contributed to the successful development of environmentally friendly composites, as most natural fibers and nanoclays are also hydrophilic in nature. Compatibilizers and the technol. of reactive extrusion are used to improve the interfacial adhesion between natural and synthetic polymers.
43. Ammar, I.; Ben Cheikh, R.; Campos, A. R.; Cunha, A. M.; Campos, A. R. Injection molded composites of short alfa fibers and biodegradable blends. Polymer Composites (2006), 27(4), 341-348. Fully biodegradable composites made from two polymer blend matrixes (SEVA-C: starch and a copolymer of ethylene vinyl alc.; and SCA: starch and cellulose acetate) and short Alfa fibers were developed and processed by conventional injection molding into std. tensile specimens. For each kind of matrix, the influence of the reinforcement load was evaluated, using fiber amts. from 0 to 30% (wt/wt). An optimization study was carried out for the composite SEVA-C with 10% Alfa fiber. The obtained results establish that the produced biodegradable composites present a significant improvement in stiffness for both matrixes. Improvements in the tensile strength were obsd. only for the Alfa fiber reinforced SEVA-C. However, for both matrixes, the reinforcement causes a significant loss in the material ductility. Results from design of expts. (Hadamard plans) were used to explain the influence of the injection molding conditions on the mech. behavior of the obtained composites, mainly on the stiffness values. Cunha, A. M.; Campos, A. R.; Cristovao, C.; Vila, C.; Santos, V.; Parajo, J. C..Sustainable materials in automotive applications. Plastics, Rubber and Composites (2006), 35(6/7), 233-241. The potential use of sustainable polymer based composites, obtained from renewable resources, is revised in terms of properties and envisaged applications. Using the typical specifications required within the automotive industry as ref., the potential of these composites is evaluated and some alternative routes for property improvement are discussed. Specific examples of the development of biodegradable polymeric composites are presented including the use of different types of matrixes, e.g. starch based blends and poly(lactic acid), and two types of natural reinforcements, i.e. fibers from pine and cellulose. This paper also presents and compares the mech. properties and morphologies obtained on injection molding composite parts made with different combinations of biodegradable matrixes and fiber reinforcements subjected to different phys. and chem. treatments. The damage caused to the fibers during the compounding and injection molding processing stages was studied too. Endres, Hans-Josef; Pries, Andreas.. Mechanical properties of starch -filled polymer compounds. Starch/Staerke (1995), 47(10), 384-93. Important mech. properties of native potato, maize and wheat starch granules were detd. With these results and under precondition of a sufficient interfacial quality the resulting mech. properties of composites reinforced with starch granules could be predicted theor. These theor. calcd. mech. parameters have been verified by tensile tests of the different composite materials. For evaluation of the interfacial quality a model for failure of unidirectional reinforced materials has been used, applied to the investigated composites and discussed in detail using some biodegradable composites as examples. The mech. properties of the matrix materials could be improved by their reinforcement with starch granules. At the same time the final costs of the composite materials could be reduced in consequence of the low costs of native starch of about 1 DM/kg and the degrdn. behavior could also have been accelerated by an increasing amt. of starch. The max. amt. of starch has been limited to 40%. Up to this filling ratio the examd. materials allowed processing almost without complications. 7.2) Referencias sobre materiales compuestos a base de almidón y/o acetato de celulosa
44. Garlotta, Donald; Doane, William; Shogren, Randal; Lawton, John; Willett, J. L. Mechanical and thermal properties of starch-filled poly(DL-lactic acid)/poly(hydroxy ester ether) biodegradable blends. Journal of Applied Polymer Science (2003), 88(7), 1775-1786. The mech., structural, and thermal properties of injection-molded composites of granular cornstarch with poly(DL-lactic acid) (PDLLA) and poly(hydroxy ester ether) (PHEE) were investigated. The composites have tensile strength 17-66 MPa at starch loading 0-70 wt%. SEM micrographs of fracture specimens reveal good adhesion of the starch granule with the polymer matrix. The starch/matrix adhesion is greatest when the matrix PDLLA/PHEE ratio is 0-1. At PDLLA/PHEE ratio <1, as the starch content increases, the tensile strength and modulus increase, while the elongation at break decreases. The effects of starch on the mech. properties of the PDLLA composites shows that as the starch content increases, the tensile strength and elongation to break decrease, while the Young's modulus increases. In contrast, the tensile strength of the PHEE composites increases with increasing starch content. Gattin, Richard; Copinet, Alain; Bertrand, Celine; Couturier, Yves. Biodegradation study of a starch and poly(lactic acid) co-extruded material in liquid, composting and inert mineral media. Biodegrdn. of a co-extruded starch/poly(lactic acid) polymeric film was studied in liq., inert solid, and composting media. Main mech. properties of this film were Young's modulus: 2340 MPa; elongation at break: 50%; and contact angle: 118 ° . Mineralization of the material C content was followed using appropriate exptl. methods of the International Std. Organization. Whatever the biodegrdn. medium used, the percentage of mineralization was better than the required 60% value for definition of a biodegradable material. Moreover, re-partitioning of material C between various degrdn. products was quantified throughout the duration of exptl. runs. The presence of starch facilitated biodegrdn. of the polylactic component, esp. in liq. media. Hokens, D.; Mohanty, A. K.; Misra, M.; Drzal, L. T. Environment-friendly " green " biodegradable composites from natural fiber and cellulosic plastic. Polymer Preprints (American Chemical Society, Division of Polymer Chemistry) (2001), 42(2), 71-72. To produce biodegradable materials of com. value, an expensive biopolymer (cellulose acetate) was mixed with an inexpensive natural fiber (henequen leaf) as a filler and a biocomposite was fabricated using powder impregnation processing. Thermal and mech. properties of the resulting biocomposite were examd. Surface modification (5% aq. NaOH, 1 h) improved fiber-matrix adhesion and thus the performance of the biocomposite. Lee, Sang Hwan; Lee, Sang Yool; Nam, Jae Do; Lee, Youngkwan. Preparation of cellulose diacetate/ramie fiber biocomposites by melt processing. Polymer ( (2006), 30(1), 70-74. Plasticized cellulose diacetate (CDA) was prepd. by homogenizing cellulose diacetate (CDA), triacetin (TA), and epoxidized soybean oil (ESO) in a high-speed mixer, then the CDA mixt. was mixed with ramie fiber to produce a green composite material. In DMA anal., the glass transition temp. of plasticized CDA and the composite was obsd. at 85 ° C and 140 ° C, resp. A composite reinforced with alkali treated ramie fiber exhibited significantly higher mech. properties, such as 15% increase in tensile strength as well as 41% increase in Young's modulus when compared with com. polypropylene. In the SEM image anal., much enhanced adhesion between plasticized CDA and alkali treated ramie fiber (AlRa) was obsd.
45. Mayer, Jean M.; Elion, Glenn R.; Buchanan, Charles M.; Sullivan, Barbara K.; Pratt, Sheldon D.; Kaplan, David L.Biodegradable blends of cellulose acetate and starch : Production and properties. Plastics Engineering (New York) (1995), 29(Degradable Polymers, Recycling, and Plastics Waste Management), 183-93. Blends of cellulose acetate (CA, 2.5 degree of substitution) and starch (St) were melt processed and evaluated for mech. properties, biodegradability during composting, and marine and soil toxicity. Formulations contg., on a wt. basis, 57% CA, 25% corn St and 19% propylene glycol (PG) had mech. properties similar to polystyrene. Increasing plasticizer or St content lowered tensile strength. Simulated municipal composting of CA alone showed losses of 2-3 and 90% dry wt. after 30 and 90 days, resp. CA/St/PG blends in both soil burial and composting expts. indicate that PG and St are degraded first. Extended incubations are required to detect losses from CA. Marine toxicity tests using polychaete worms and mussels showed no toxicity of CA or St. High doses had an adverse effect due to oxygen depletion in the marine water due to rapid biodegrdn. of the polymers. Preliminary plant toxicity tests of the CA/St blends showed no neg. impact on growth and yield for sweet corn, butternut squash, and plum tomatoes. The results indicate that CA/St blends have acceptable properties for injection-molded applications and are biodegradable and nontoxic. Onteniente, Jean-Paul; Safa, Laurent Haidar; Abbes, Boussad. Process for making new biofragmentable materials : comparative study of the physical properties of wheat starch and cellulose acetate blends and those of wheat starch and starch acetate blends. Bio-fragmentable starch blends were obtained by extrusion, using either wheat starch and cellulose acetate dry blends, in which the degree of substitution (DS) of cellulose acetate was close to 2.3, or wheat starch and starch acetate dry blends in which the DS of starch acetate was around 1.5. After prepn., the dry blends were stored for one week at 20 ° and 65% relative humidity (RH) before being injection molded to produce standardized samples for tensile tests. Tensile strength tests (ISO/R527) and Charpy shock tests (ISO/R179) were carried out on the injection molded samples after having been stored under the same conditions of temp. and RH. The dimensional stability of the samples was estd. by measuring the volumetric shrinkage after storage. The hydrophobic behavior of the blends was evaluated by measuring the development of the contact angle of a drop of water placed on the samples. Starch was not compatible with 2.3 DS cellulose acetate. The samples prepd. with starch and 2.3 DS cellulose acetate blends had a thin surface layer composed of cellulose diacetate; this layer increased the hydrophobicity. The samples prepd. with starch and 1.5 DS starch acetate blends were globally homogeneous and did not exhibit any surface layer, but the blends were less hydrophobic than the 2.3 DS cellulose acetate blends.
46. Viana P.; Vallo, Claudia; Kenny, Jose M.; Vazquez, Analia. Effect of chemical treatment on the mechanical properties of starch-based blends reinforced with sisal fiber. Journal of Composite Materials (2004), 38(16), 1387-1399. The effect of chem. treatment of sisal fibers on mech. properties of fiber-reinforced biodegradable plastics (biocomposites) was investigated. The biocomposites were produced by extrusion of polycaprolactone/starch blends (Mater-Bi-Z ZF 03) as the matrix with washed or sodium hydroxide- or acetic acid-treated sisal fibers as a reinforcement. The alk. or acetylation treatment of the fibers was carried out to enhance adhesion and compatibility between the fibers and the matrix. Tensile properties of the biodegradable composite were improved by the presence of the fibers. The untreated fibers showed better reinforcing properties than the acetylated or alkali-treated fibers. This was attributed to an impairment of the mech. properties of the acetylated fibers and incompatibility of the alkali-treated fibers. The results were supported by SEM anal. of the fibers and the composite materials. Wollerdorfer, Martina; Bader, Herbert. Influence of natural fibers on the mechanical properties of biodegradable polymers. Industrial Crops and Products (1998), 8(2), 105-112. Fiber reinforced plastics are used whenever there is the need for very high mech. properties combined with low wt. In that respect natural fibers are of basic interest since they not only have the functional capability to substitute the widely used glass fibers but they also have advantages from the point of view of wt. and fiber-matrix adhesion, specifically with polar matrix materials. They have good possibilities in waste management due to their biodegradability on the one hand and their much lower prodn. of ash during incineration on the other. The influence of plant fibers such as flax, jute, ramie, oil palm fibers and fibers made from regenerated cellulose on the mech. properties of biodegradable polymers was investigated using thermoplastics like polyesters, polysaccharides and blends of thermoplastic starch. The composites were produced by extrusion compounding with a co-rotating twin screw extruder. The pellets obtained were further processed into tensile test bars by injection molding. Depending on the kind of polymer, a fiber content of 20-35% could be achieved. Generally a considerable tensile strength improvement of polyesters could not be obsd. However the chem. similarity of polysaccharides and plant fibers, which consist mainly of cellulose, resulted in an increased tensile strength of the reinforced polymers. For reinforced thermoplastic wheat starch, it was four times better (37 N/mm2) than without fibers. The reinforcement of cellulose diacetate and starch blends caused a stress increase of 52% (55 N/mm2) and 64% (25 N/mm2), resp.
47. Ben, Goichi; Kihara, Yuichi. Development and evaluation of mechanical properties for Kenaf fibers /PLA composites. Key Engineering Materials (2007), 334-335(Pt. 1, Advances in Composite Materials and Structures), 489-492. A new type of composite used biodegradable resins and natural fibers is now being developed and this new type of composites is designated as a green composite. This paper presents a fabrication method and mech. properties of the green composite used Kenaf fibers as the reinforcement and PLA as the matrix. In order to obtain the higher tensile strength, various kind of surface treatments were executed on the Kenaf fiber and some parameters were changed during the process of fabrication. Then, these effects on the strength of green composite are also reported. Chen, Chien-Chung; Chueh, Ju-Yu; Tseng, How; Huang, Haw-Ming; Lee, Sheng-Yang Preparation and characterization of biodegradable PLA polymeric blends. Biomaterials (2003), 24(7), 1167-1173. The purpose of this study was to fine-tune the mech. properties of high mol.-wt. poly-l-lactic acid (PLLA), esp. to increase its toughness without sacrificing too much of its original strength. Besides of its long degrdn. time, PLLA is usually hard and brittle, which hinders its usage in medical applications, i.e., orthopedic and dental surgery. Some modifications, such as the addn. of plasticizers or surfactants/compatibilizers, are usually required to improve its original properties. PDLLA can degrade quickly due to its amorphous structure, thus shortening the degrdn. time of PLLA/PDLLA blends. Blends of biodegradable poly-l-lactic acid (PLLA) and poly-dl-lactic acid (PDLLA) or polycaprolactone (PCL), in addn. to a third component, the surfactant-a copolymer of ethylene oxide and propylene oxide, were prepd. by blending these three polymers at various ratios using dichloromethane as a solvent. The wt. percentages of PLLA/PDLLA (or PCL) blends were 100%/0%, 80%/20%, 60%/40%, 50%/50%, 40%/60%, 20%/80% and 0%/100%, resp. Phys. properties such as the cryst. m.p., glass transition point (Tg), phase behavior, degrdn. behavior, and other mech. properties were characterized by thermogravimetric anal., DSC, IR spectroscopy, gel permeation chromatog., and dynamic mech. anal. (DMA). DSC data indicate that PLLA/PDLLA blends without the surfactant had two Tg's. With the addn. of the surfactant, there was a linear shift of the single Tg as a function of compn., with lower percentages of PLLA producing lower glass transition temps. indicating that better miscibility had been achieved. DMA data show that the 40/60 PLLA/PDLLA blends without the surfactant had high elastic modulus and elongation, and similar results were obsd. after adding 2% surfactant into the blends. The 50/50 PLLA/PDLLA/2% surfactant blend had the highest elastic modulus, yield strength, and break strength compared with other ratios of PLLA/PDLLA/2% surfactant blends. The elongation at break of 50/50 PLLA/PDLLA was similar to that of PLLA. Again, the elongation at break of 50/50 PLLA/PDLLA/2% surfactant was almost 1.2-1.9 times higher than that of 50/50 PLLA/PDLLA and PLLA. Elongation of PLLA increased with the addn. of PCL, but the strength decreased at the same time. In conclusions, adding PDLLA and surfactant to PLLA via soln.-blending may be an effective way to make PLLA tougher and more suitable to use in orthopedic or dental applications. 7.3) Referencias sobre materiales compuestos a base de PLA
48. Cunha, A. M.; Campos, A. R.; Cristovao, C.; Vila, C.; Santos, V.; Parajo, J. C..Sustainable materials in automotive applications. Plastics, Rubber and Composites (2006), 35(6/7), 233-241. The potential use of sustainable polymer based composites, obtained from renewable resources, is revised in terms of properties and envisaged applications. Using the typical specifications required within the automotive industry as ref., the potential of these composites is evaluated and some alternative routes for property improvement are discussed. Specific examples of the development of biodegradable polymeric composites are presented including the use of different types of matrixes, e.g. starch based blends and poly(lactic acid), and two types of natural reinforcements, i.e. fibers from pine and cellulose. This paper also presents and compares the mech. properties and morphologies obtained on injection molding composite parts made with different combinations of biodegradable matrixes and fiber reinforcements subjected to different phys. and chem. treatments. The damage caused to the fibers during the compounding and injection molding processing stages was studied too. Garlotta, Donald. A literature review of poly(lactic acid). Journal of Polymers and the Environment (2002), Volume Date 2001, 9(2), 63-84. A literature review is presented regarding the synthesis and physicochem., chem., and mech. properties of poly(lactic acid) (PLA). PLA exists as a polymeric helix, with an orthorhombic unit cell. The tensile properties of PLA can vary widely, depending on whether or not it is annealed or oriented or what its degree of crystallinity is. Also discussed are the effects of processing on PLA. Crystn. and crystn. kinetics are examd. Soln. and melt rheol. is also discussed. Four different power-law equations and 14 different Mark-Houwink equations are presented. NMR, UV-visible, and FTIR spectroscopy of PLA are briefly discussed. Finally, research conducted on starch-PLA composites is introduced. Garlotta, Donald; Doane, William; Shogren, Randal; Lawton, John; Willett, J. L. Mechanical and thermal properties of starch-filled poly(DL-lactic acid)/poly(hydroxy ester ether) biodegradable blends. Journal of Applied Polymer Science (2003), 88(7), 1775-1786. The mech., structural, and thermal properties of injection-molded composites of granular cornstarch with poly(DL-lactic acid) (PDLLA) and poly(hydroxy ester ether) (PHEE) were investigated. The composites have tensile strength 17-66 MPa at starch loading 0-70 wt%. SEM micrographs of fracture specimens reveal good adhesion of the starch granule with the polymer matrix. The starch/matrix adhesion is greatest when the matrix PDLLA/PHEE ratio is 0-1. At PDLLA/PHEE ratio <1, as the starch content increases, the tensile strength and modulus increase, while the elongation at break decreases. The effects of starch on the mech. properties of the PDLLA composites shows that as the starch content increases, the tensile strength and elongation to break decrease, while the Young's modulus increases. In contrast, the tensile strength of the PHEE composites increases with increasing starch content.
49. Gattin, Richard; Copinet, Alain; Bertrand, Celine; Couturier, Yves. Biodegradation study of a starch and poly(lactic acid) co-extruded material in liquid, composting and inert mineral media. International Biodeterioration & Biodegradation (2002), 50(1), 25-31. Biodegrdn. of a co-extruded starch/poly(lactic acid) polymeric film was studied in liq., inert solid, and composting media. Main mech. properties of this film were Young's modulus: 2340 MPa; elongation at break: 50%; and contact angle: 118 ° . Mineralization of the material C content was followed using appropriate exptl. methods of the International Std. Organization. Whatever the biodegrdn. medium used, the percentage of mineralization was better than the required 60% value for definition of a biodegradable material. Moreover, re-partitioning of material C between various degrdn. products was quantified throughout the duration of exptl. runs. The presence of starch facilitated biodegrdn. of the polylactic component, esp. in liq. media. Hu, Ruihua; Lim, Jae-Kyoo .Fabrication and mechanical properties of completely biodegradable hemp fiber reinforced polylactic acid composites. Journal of Composite Materials (2007), 41(13), 1655-1669. Biodegradable composite materials can be produced by the combination of biodegradable polymers and natural fibers. In this study, a new biodegradable composite of hemp fiber reinforced polylactic acid (PLA) was fabricated using the hot press method. Mech. properties of composites with different fiber vol. fractions were tested. The optimum fiber content was detd. according to the test results. Effects of alkali treatment on the fiber surface morphol. and the mech. properties of the composites were investigated. Test results show that the composite with 40% vol. fraction of alkali treated fiber has the best mech. properties. The tensile strength, elastic modulus, and flexural strength of the composite with 40% treated fiber are 54.6 MPa, 8.5 Gpa, and 112.7 MPa resp., which are much higher than those of PLA alone. The composites have lower densities, which were measured to be from 1.19 g/cm3 to 1.25 g/cm3. Specific strengths were also calcd. Surface morphologies of fiber and fracture surfaces of the composites were obsd. using the SEM method. Huda, M. S.; Mohanty, A. K.; Drzal, L. T.; Schut, E.; Misra, M. "Green" composites from recycled cellulose and poly(lactic acid): Physico-mechanical and morphological properties evaluation. Journal of Materials Science (2005), 40(16), 4221-4229. "Green"/biobased composites were prepd. from poly(lactic acid) (PLA) and recycled cellulose fibers (from newsprint) by extrusion followed by injection molding processing. The physico-mech. and morphol. properties of the composites were investigated as a function of varying amts. of cellulose fibers. Compared to the neat resin, the tensile and flexural moduli of the composites were significantly higher. This is due to higher modulus of the reinforcement added to the PLA matrix. Dynamic mech. anal. (DMA) results also confirmed that the storage modulus of PLA increased on reinforcements with cellulose fibers indicating the stress transfers from the matrix resin to cellulose fiber. Differential scanning calorimetry (DSC) and thermogravimetric anal. (TGA) showed that the presence of cellulose fibers did not significantly affect the crystallinity, or the thermal decompn. of PLA matrix up to 30 wt% cellulose fiber content. Overall it was concluded that recycled cellulose fibers from newsprint could be a potential reinforcement for the high performance biodegradable polymer composites.
50. Lunt, James. Large-scale production, properties and commercial applications of polylactic acid polymers. Polymer Degradation and Stability (1998), 59(1-3), 145-152. A review with 6 refs. on lactic acid polymers (PLA). Recent developments in the capability to manuf. the monomer economically from renewable feedstocks have placed these materials at the forefront of the emerging biodegradable plastics industry. Increasing realization of the intrinsic properties of these polymers, coupled with a knowledge of how such properties can be manipulated to achieve compatibility with thermoplastics processing, manufg., and end-use requirements has fueled technol. and com. interest in PLA products. This paper discusses the various technologies being used to produce polylactic acids. In addn., attention is drawn to how monomer stereochem. can be controlled to impart targeted utility in the final polymers. Specific applications are described to illustrate further the range of properties that can be developed by utilizing both the basic monomer/polymer chemistries in combination with post-modification techniques. Finally, the biodegrdn. mechanism of polylactic acids will be discussed and contrasted with other biodegradable polymers. Mohamed, Abdellatif A.; Finkenstadt, V. L.; Palmquist, Debra E. Thermal properties of extruded-injection molded poly (lactic acid) and milkweed composites. Proceedings of the NATAS Annual Conference on Thermal Analysis and Applications (2007), 35th 26#769/1-26#769/7. Currently, most polymer composites utilize petroleum-based materials that are non-degradable and difficult to recycle or incur substantial cost for disposal. Green composites can be used in nondurable limited applications. In order to det. the degree of compatibility between Poly (lactic Acid) (PLA) and different biomaterials, PLA was compounded with milkweed fiber. Milkweed is a new crop oil seed. After oil extn., the remaining cake retained approx. 10% residual oil and 47% protein. The pressed seed cake (10% moisture) was ground and passed through a 300 m m screen. The fiber was added at 85:15 and 70:30 PLA:Fiber. The composites were blended by extrusion (EX) followed by injection molding (EXIM). Differential Scanning Calorimetry (DSC) and Thermogravimetric Anal. (TGA) were used to analyze the EX and the EXIM composites. The effect of the fiber on the enthalpic relaxation (ER) of PLA was detd. by aging. After melting in the DSC sealed pans, composites were cooled by immersion in liq. nitrogen and aged (stored) at room temp. for 0, 7, 15, and 30 days. After storage, samples were heated from room temp. to 180 ° C at 10 ° C/min. The pure PLA showed a glass transition (Tg) at 59 ° C and the corresponding D Cp was 0.464 J/g/ ° C. The PLA glass transition was followed by crystn. and melting transitions. The ER of neat PLA and composites steadily increased as a function of storage time. Although the presence of fiber has little effect on ER, injection molding reduced ER. The percentage crystallinity of neat unprocessed PLA dropped, as a result of EX, by 95% and by 80% for the EXIM. The degrdn. was done in air and nitrogen environment. The degrdn. Activation Energy (Ea) of neat PLA exhibited a significant drop in nitrogen environment, while increased in air, indicating PLA resistant to degrdn. in the presence of oxygen. Overall, injection molding appeared to reduce Ea of the composite. Milkweed significantly reduced Ea values in a nitrogen environment, while in air Ea exhibited increased values. Enzymic degrdn. of the composites showed a higher degrdn. rate for the EX samples vs. EXIM, while 30% milkweed exhibited higher wt. loss compared to the 15%.
51. Nishino, Takashi; Hirao, Koichi; Kotera, Masaru; Nakamae, Katsuhiko; Inagaki, Hiroshi. Kenaf reinforced biodegradable composite. Composites Science and Technology (2003), 63(9), 1281-1286. Mech. properties of environmentally friendly composites made of kenaf fiber and poly-l-lactic acid (LACEA) resin were investigated. The Young's modulus (6.3 GPa) and tensile strength (62 MPa) of the composites (fiber content 70 vol.%) were comparable to those of conventional fiber composites. These properties were higher than those of the kenaf sheet and the LACEA film themselves. This is considered to attribute to the strong interaction between the fiber and LACEA. In addn., the storage modulus of the composite remain unchanged up to the LACEA m.p. The effects of the polymer mol. wt. and the fiber orientation on the mech. properties of the composite were also investigated. It was found that kenaf fiber can be a good candidate for the reinforcement fiber of high performance biodegradable polymer composites. Oksman, K.; Skrifvars, M.; Selin, J.-F Natural fibres as reinforcement in polylactic acid (PLA) composites. Composites Science and Technology (2003), 63(9), 1317-1324. The focus in this work has been to study if natural fibers can be used as reinforcement in polymers based on renewable raw materials. The materials were flax fibers and poly(lactic acid) (PLA). PLA is a thermoplastic polymer made from lactic acid and has mainly been used for biodegradable products, such as plastic bags and planting cups, but in principle PLA can also be used as a matrix material in composites. Because of the brittle nature of PLA triacetin was tested as plasticizer for PLA and PLA/flax composites in order to improve the impact properties. The studied composite materials were manufd. with a twin-screw extruder having a flax fiber content of 30 and 40 wt.%. The extruded compd. was compression molded to test samples. The processing and material properties were studied and compared to the more commonly used polypropylene-flax fiber composites (PP/flax). Preliminary results show that the mech. properties of PLA and flax fiber composites are promising. The composite strength is about 50% better compared to similar PP/flax fiber composites, which are used today in many automotive panels. The addn. of plasticizer does not show any pos. effect on the impact strength of the composites. The study of interfacial adhesion shows that adhesion needs to be improved to optimize the mech. properties of the PLA/flax composites. The PLA/flax composites did not show any difficulties in the extrusion and compression molding processes and they can be processed in a similar way as PP based composites.
52. Pan, Pengju; Zhu, Bo; Kai, Weihua; Serizawa, Shin; Iji, Masatoshi; Inoue, Yoshio. Crystallization behavior and mechanical properties of bio-based green composites based on poly(L-lactide) and kenaf fiber. Bio-based polymer composite was successfully fabricated from plant-derived kenaf fiber (KF) and renewable resource-based biodegradable polyester, poly(L-lactide) (PLLA), by melt-mixing technique. The effect of the KF wt. contents (0, 10, 20, and 30 wt %) on crystn. behavior, composite morphol., mech., and dynamic mech. properties of PLLA/KF composites were investigated. It was found that the incorporation of KF significantly improves the crystn. rate and tensile and storage modulus. The crystn. of PLLA can be completed during the cooling process from the melt at 5 ° C/min with the addn. of 10 wt % KF. It was also obsd. that the nucleation d. increases dramatically and the spherulite size drops greatly in the isothermal crystn. with the presence of KF. In addn., with the incorporation of 30 wt % KF, the half times of isothermal crystn. at 120 ° C and 140 ° C were reduced to 46.5% and 28.1% of the pure PLLA, resp. Moreover, the tensile and storage modulus of the composite are improved by 30% and 28%, resp., by the reinforcement with 30% KF. SEM observation also showed that the crystn. rate and mech. properties could be further improved by optimizing the interfacial interaction and compatibility between the KF and PLLA matrix. Overall, it was concluded that the KF could be the potential and promising filler for PLLA to produce biodegradable composite materials, owing to its good ability to improve the mech. properties as well as to accelerate the crystn. of PLLA. Serizawa, Shin; Inoue, Kazuhiko; Iji, Masatoshi. Kenaf-fiber-reinforced poly(lactic acid) used for electronic products. Journal of Applied Polymer Science (2006), 100(1), 618-624. High-performance biomass-based composites were fabricated with poly(lactic acid) (PLA) and kenaf fibers, which fixate CO2 efficiently. The composites show good thermal stability (distortion temp. under load) and modulus and the fibers enhance crystn. of PLA, to facilitate molding of the material. The effect of recycling on the composites was also assessed. Eliminating short particles from kenaf fibers resulted in improved impact strength of the composites. Kenaf fibers without particles are practically comparable to glass fibers. The mech. strength of the composites was further improved by using a plasticizer of a copolymer of lactic acid and an aliph. polyester. The composites (PLA/kenaf fiber and PLA/kenaf fiber/plasticizer) show good practical characteristics for use as housing materials of electronics, comparable to petroleum-based composites such as glass fiber - acrylonitrile-butadiene-styrene (ABS) resin.
53. Shibata, Mitsuhiro; Ozawa, Koichi; Teramoto, Naozumi; Yosomiya, Ryutoku; Takeishi, Hiroyuku. Biocomposites made from short abaca fiber and biodegradable polyesters. Macromolecular Materials and Engineering (2003), 288(1), 35-43. Natural fiber-reinforced biodegradable polyester composites were prepd. from biodegradable polyesters and surface-untreated or -treated abaca fibers (length .apprx.5 mm) by melt mixing and subsequent injection molding. Poly(butylene succinate)(PBS), polyester carbonate (PEC)/poly(lactic acid)(PLA) blend, and PLA were used as bio-degradable polyesters. Esterifications using acetic anhydride and butyric anhydride, alkali treatment, and cyanoethylation were performed as surface treatments on the fiber. The flexural moduli of all the fiber-reinforced composites increased with fiber content. The effect of the surface treatment on the flexural modulus of the fiber-reinforced composites was not so pronounced. The flexural strength of PBS composites increased with fiber content, and esterification of the fiber by butyric anhydride gave the best result. For the PEC/PLA composites, flexural strength increased slightly with increased fiber content (0-20 wt.-%) in the case of using untreated fiber, while it increased considerably in the case of using the fiber esterified by butyric anhydride. For the PLA composite, flexural strength did not increase with the fiber reinforcement. The result of soil-burial tests showed that the composites using untreated fiber have a higher wt. loss than both the neat resin and the composites made using acetylated fiber. Tanaka, Chiaki; Vu, Minh Duc; Okubo, Kazuya; Fujii, Toru. Development of green composites using micro-fibrillated bamboo fibers -application to inject molding. Bamboo Journal (2007), 24 17-26. Green composites using micro-fibrillated cellulose fibers extd. from bamboo (MFB) for injection molding were developed in conjunction with PLA. PLA has a function to give viscosity to the compds. while MFB assure the high mech. performance at not only room but also elevated temps. MFB was mixed with water based PLA since MFB contained a lot of water for handling. No micro/nano fibers can be utilized if dried MFB is powd. Less than 50% MFB was included in PLA based compds. and the bending and impact strengths were measured at room temp. The test results confirmed that injection molding was achieved when MFB wt. % content was 30% or lower at 170, 180 and 190 ° C when MFB was mixed with PLA in water. The bending strength and elastic modulus of MFB/PLA composites increased by 1.8 times and 1.5 times as high as the original PLA in the case of 30 wt% MFB. The impact strength of MFB/PLA composites evaluated by the Izod impact test was also improved in the case of 10 wt% MFB while it decreased in the case of 30 wt% MFB. Vink, Erwin T. H.; Rabago, R.; Glassner, David A.; Springs, Bob; O'Connor, Ryan P.; Kolstad, Jeff; Gruber, Patrick R. The sustainability of Nature Works polylactide polymers and Ingeo polylactide fibers: An update of the future. Macromolecular Bioscience (2004), 4(6), 551-564. A review on Cargill Dow company activities in the area of green chem. with focus on polylactide polymer chem. The following topics are discussed: NatureWorks polylactide prodn. process, today's and future products from NatureWorks polylactide, Ingeo fibers, other materials from lactic acid, the pursuit of sustainability, the "ideal" sustainable material, biomass utilization and biorefineries, poly(lactic acid) (PLA) life cycle inventory impacts of wind power renewable energy certificates to offset net (residual) greenhouse gases emissions, future price trends on PLA, waste management options, composting, chem. recycling, and what makes NatureWorks PLA a more sustainable polymer.
54. Wang, L.; Ma, W.; Gross, R. A.; McCarthy, S. P.Reactive compatibilization of biodegradable blends of poly(lactic acid) and poly( e -caprolactone). Polymer Degradation and Stability (1998), 59(1-3), 161-168. Poly( e -caprolactone) (PCL) was reactively blended with poly(lactic acid) (PLA) using three catalysts/coupling agents in a twin screw mixing chamber. Ph3PO3 showed the most promising results as a coupling or branching agent. PLA and PCL were also melt blended without any catalyst/coupling agents in order to make a comparison of the properties. The transesterification reaction was monitored by measuring torque values as a function of time. 1H NMR was used to characterize the structure of the reactive and phys. blend products. The blend samples were characterized for phys. properties and biodegrdn. Mech. property measurements indicated that the elongation of the PLA/PCL blends improved significantly when compared to pure PLA esp. for the reactively compatibilized blends, and that a synergism was obsd. for certain compns. (PLA/PCL = 80/20 or 20/80). Degrdn. studies showed that the enzymic degrdn. rates (or normalized wt. loss) of the reactively compatibilized blends were much higher than that of pure PLA and PCL, while the degrdn. rates of phys. blends are between those of pure PLA and PCL. Wong, S.; Shanks, R. A.; Hodzic, A. Effect of additives on the interfacial strength of poly(L-lactic acid) and poly(3-hydroxy butyric acid)-flax fiber composites. Composites Science and Technology (2007), 67(11-12), 2478-2484. The interfacial shear strength (IFSS), evaluated by single fiber pull-out tests was quantified for various biopolymer-flax fiber composites that were modified with additives. The additives included a plasticizer (glycerol triacetate) (GTA) absorbed onto/into the fibers, 4,4'-thiodiphenol (TDP) that is capable of forming hydrogen bonds between the matrix and cellulose from the fibers, and a hyperbranched polyester (HBP) to impart improved fracture toughness. Fibers were washed with acetone to remove the surface impurities and dried under vacuum before absorption of plasticizer and adsorption of thiodiphenol. It was found that the different additives significantly influenced the IFSS for the biopolymer-flax fiber systems while extn. with acetone had a no effect on the IFSS compared with the untreated fibers. The use of TDP imparted the most significant increase in IFSS while the HBP had an opposing effect. The use of ESEM corroborated with the findings of the single fiber pull-out tests. Yu, Long; Petinakis, Steven; Dean, Katherine; Bilyk, Alex; Wu, Dongyang. Green polymeric blends and composites from renewable resources. Macromolecular Symposia (2007), 249/250(Advanced Polymers for Emerging Technologies), 535-539. Currently new blends and composites are extending the utilization of polymers from renewable resources into new value-added products. This paper briefly discusses the development in this area, and introduces our research, in particular the starch-based nanocomposites, biodegradable polyester/starch blends and cellulose-reinforced PLA composites. It can be seen that hydrophilic character of natural polymers has contributed to the successful development of environmentally friendly composites, as most natural fibers and nanoclays are also hydrophilic in nature. On the other hand, hydrophobic property and moisture sensitivity of biodegradable polyesters are challenge to be reinforced by the natural materials.
55. Alessandro; Botaro, Vagner; Zeno, Elisa; Bach, Sylvie. Activation of solid polymer surfaces with bifunctional reagents. Polymer International (2001), 50(1), 7-9. An original procedure is described which calls upon the heterogeneous grafting of bifunctional mols. onto a reactive polymeric surface, leaving 1 of the functions available for further exploitation. The principle of this strategy is to use reagents characterized by a rigid planar structure bearing the 2 active moieties at opposite sites of the mol. The examples provided include the reactions of lignocellulosic fibers with 1,4-phenylene diisocyanate and 1,2,4,5-benzenetetracarboxylic anhydride, which give rise to their surface activation through the incorporation of covalently bound isocyanate or anhydride functions. Ammar, I.; Ben Cheikh, R.; Campos, A. R.; Cunha, A. M.; Campos, A. R. Injection molded composites of short alfa fibers and biodegradable blends. Polymer Composites (2006), 27(4), 341-348. Fully biodegradable composites made from two polymer blend matrixes (SEVA-C: starch and a copolymer of ethylene vinyl alc.; and SCA: starch and cellulose acetate) and short Alfa fibers were developed and processed by conventional injection molding into std. tensile specimens. For each kind of matrix, the influence of the reinforcement load was evaluated, using fiber amts. from 0 to 30% (wt/wt). An optimization study was carried out for the compos