This document discusses polymeric and composite materials, specifically:
1. It defines polymers as long molecular chains made of repeating units and describes the three main types: thermoplastics, thermosets, and elastomers.
2. Thermoplastics can be remelted and reshaped, thermosets permanently set during curing, and elastomers are highly elastic.
3. It provides examples of common polymers and explains how they are synthesized through addition or step polymerization of monomers into long chains.
The document discusses different types of polymers including thermoplastics, thermosets, and elastomers. It provides details on their molecular structures, properties, production methods, and common applications. Thermoplastics are solid but soften when heated, thermosets permanently harden when heated, and elastomers can stretch greatly and recover their original shape. Additives are used to modify polymer properties for different applications. The largest markets are thermoplastics like polyethylene and polypropylene for products and packaging.
This document provides an introduction to polymer science, including definitions of key terms like polymer, monomer, oligomer, and degree of polymerization. It discusses various classifications of polymers such as by origin, monomer composition (homopolymer, copolymer), chain structure, configuration, and thermal behavior. Mechanisms of polymerization including step-growth and chain-growth are introduced. Physical properties of polymers related to their structure like crystallinity, glass transition temperature, and elastomers are also covered.
Polymer refers to large molecules made of repeating structural units called monomers. Naturally occurring polymers include proteins, cellulose, and starch, while synthetic polymers like nylon and polyester are widely used in engineering applications. Polymers can be classified based on their origin, monomer composition, chain structure, thermal behavior, and application. Common physical properties of polymers include their glass transition temperature, crystalline structure, and responses to heat. Examples of important polymers discussed in the document include polyethylene, which exists in various densities, and polypropylene.
This document discusses various types of polymer matrix composites, their processing techniques, and applications. It begins by defining polymer matrix composites and describing different types of matrices, including thermoset and thermoplastic polymers. Several processing methods for thermoset composites are then outlined, such as hand layup, filament winding, and resin transfer molding. Common thermoplastic processing techniques like injection molding and film stacking are also mentioned. The document concludes by noting some applications of polymer matrix composites.
This document discusses various types and processing techniques for polymer matrix composites. It begins by describing hand layup and sprayup techniques for composites, as well as other processes like filament winding, pultrusion, resin transfer molding, and autoclave molding. It then discusses thermoplastic matrix composites and techniques like injection molding, film stacking, and tape laying. The document provides information on glass fiber/polymer interfaces, mechanical properties, and applications of polymer matrix composites.
This document discusses polymer matrix composites. It covers types of polymer matrices including thermoset and thermoplastic polymers. Processing techniques for both thermoset and thermoplastic matrix composites like hand layup, filament winding, injection molding are described. The functions and desired properties of the polymer matrix are explained. Comparison of various polymer matrices and the effect of temperature on thermoplastics are also summarized.
Polymers can be formed through addition polymerization or step-growth polymerization. They have various molecular structures that influence properties like crystallinity. Thermoplastics soften when heated while thermosets form permanent chemical bonds. Common polymers include polyethylene, polypropylene, polystyrene, and nylon. They are processed through methods like extrusion, injection molding, and thermoforming to make a wide range of products.
This document provides an overview of polymers and rubber. It defines key polymerization terms like monomer, polymer, degree of polymerization, and discusses different types of polymerization including addition, condensation, and copolymerization. Natural rubber is made of polyisoprene and has limitations like low strength and reactivity which are addressed by vulcanization through crosslinking with sulfur. Commercial rubbers like Buna-S are discussed which is a styrene-butadiene copolymer used to make tires and insulation due to its tough mechanical properties.
The document discusses different types of polymers including thermoplastics, thermosets, and elastomers. It provides details on their molecular structures, properties, production methods, and common applications. Thermoplastics are solid but soften when heated, thermosets permanently harden when heated, and elastomers can stretch greatly and recover their original shape. Additives are used to modify polymer properties for different applications. The largest markets are thermoplastics like polyethylene and polypropylene for products and packaging.
This document provides an introduction to polymer science, including definitions of key terms like polymer, monomer, oligomer, and degree of polymerization. It discusses various classifications of polymers such as by origin, monomer composition (homopolymer, copolymer), chain structure, configuration, and thermal behavior. Mechanisms of polymerization including step-growth and chain-growth are introduced. Physical properties of polymers related to their structure like crystallinity, glass transition temperature, and elastomers are also covered.
Polymer refers to large molecules made of repeating structural units called monomers. Naturally occurring polymers include proteins, cellulose, and starch, while synthetic polymers like nylon and polyester are widely used in engineering applications. Polymers can be classified based on their origin, monomer composition, chain structure, thermal behavior, and application. Common physical properties of polymers include their glass transition temperature, crystalline structure, and responses to heat. Examples of important polymers discussed in the document include polyethylene, which exists in various densities, and polypropylene.
This document discusses various types of polymer matrix composites, their processing techniques, and applications. It begins by defining polymer matrix composites and describing different types of matrices, including thermoset and thermoplastic polymers. Several processing methods for thermoset composites are then outlined, such as hand layup, filament winding, and resin transfer molding. Common thermoplastic processing techniques like injection molding and film stacking are also mentioned. The document concludes by noting some applications of polymer matrix composites.
This document discusses various types and processing techniques for polymer matrix composites. It begins by describing hand layup and sprayup techniques for composites, as well as other processes like filament winding, pultrusion, resin transfer molding, and autoclave molding. It then discusses thermoplastic matrix composites and techniques like injection molding, film stacking, and tape laying. The document provides information on glass fiber/polymer interfaces, mechanical properties, and applications of polymer matrix composites.
This document discusses polymer matrix composites. It covers types of polymer matrices including thermoset and thermoplastic polymers. Processing techniques for both thermoset and thermoplastic matrix composites like hand layup, filament winding, injection molding are described. The functions and desired properties of the polymer matrix are explained. Comparison of various polymer matrices and the effect of temperature on thermoplastics are also summarized.
Polymers can be formed through addition polymerization or step-growth polymerization. They have various molecular structures that influence properties like crystallinity. Thermoplastics soften when heated while thermosets form permanent chemical bonds. Common polymers include polyethylene, polypropylene, polystyrene, and nylon. They are processed through methods like extrusion, injection molding, and thermoforming to make a wide range of products.
This document provides an overview of polymers and rubber. It defines key polymerization terms like monomer, polymer, degree of polymerization, and discusses different types of polymerization including addition, condensation, and copolymerization. Natural rubber is made of polyisoprene and has limitations like low strength and reactivity which are addressed by vulcanization through crosslinking with sulfur. Commercial rubbers like Buna-S are discussed which is a styrene-butadiene copolymer used to make tires and insulation due to its tough mechanical properties.
- Polymers are giant molecules formed by linking together small repeating units called monomers via covalent bonds. There are three main types of polymerization: addition, condensation, and copolymerization.
- Properties of polymers depend on factors like the monomer type, the degree of polymerization, tacticity, and whether the polymer is crystalline or amorphous. Common polymers include polyethylene, polypropylene, nylon, polyethylene terephthalate.
- Natural rubbers are polymers of the monomer isoprene that provide flexibility and elasticity. However, natural rubber has limitations that are overcome through vulcanization, which introduces cross-links between polymer chains through the addition of sulfur.
Macromolecules are large molecules formed by linking many smaller units, or monomers, through covalent bonds. Natural substances like proteins and synthetic polymers are examples of macromolecules. Monomers undergo polymerization to form macromolecules by linking together through addition or condensation reactions. Polymers can be classified in different ways such as natural vs synthetic, organic vs inorganic, thermoplastic vs thermosetting, and linear, branched or cross-linked based on their molecular structure. The process of polymerization and properties of polymers depend on factors like the type of monomers, reaction conditions and molecular architecture.
Polymer science concerns large molecules called polymers that include rubbers, plastics, and fibers. Polymers are made of repeating molecular units and have high molecular weights. There are over 60,000 scientists working with polymers today to develop new materials with customized properties. Common polymers include polypropylene, polyethylene, and nylons. Polymers can be categorized based on their molecular structure as thermoplastics, thermosets, or elastomers, which determine how they respond to heat.
The document discusses various types of polymers including thermoplastics like polyethylene, polypropylene, polyvinyl chloride, polystyrene; thermosetting plastics; polymerization methods like addition, condensation and their mechanisms; classification of polymers; properties and applications of common polymers like polyethylene, polystyrene, polyvinyl chloride and teflon. It also discusses polymer structure, degree of polymerization, tactics and various additives used in plastics.
This document discusses polymer matrix composites, which consist of a polymer matrix combined with fibrous reinforcement. It describes the different types of polymer matrices - thermosetting and thermoplastic resins. Thermosetting resins like epoxy, polyester and phenolic polymers form cross-linked networks and do not melt when heated, while thermoplastic polymers like polyethylene, polypropylene and nylon soften when heated. The properties and uses of various thermosetting and thermoplastic resins are outlined. The role of the polymer matrix in a composite is also summarized - to hold fibers together, protect them, distribute loads evenly and enhance mechanical properties.
Polymerization is a process of reacting monomer molecules together to form polymer chains. There are two main types of polymerization:
1) Addition (chain) polymerization involves linking monomers together through double or triple bonds. It includes initiation, propagation, and termination steps.
2) Condensation (step-growth) polymerization combines monomers by removing a small molecule, like in polyester formation. It does not involve chain growth.
Condensation polymerization has a lower degree of polymerization and molecular weight increases slowly as functional groups are consumed in each step. In contrast, addition polymerization can achieve very high degrees of polymerization and molecular weight increases rapidly through successive monomer additions to growing chains.
This document provides an overview of polymers, including:
- Polymers are large molecules made by linking repeating units called monomers. Naturally occurring polymers have been used for thousands of years, while artificial polymers were developed more recently after WWII.
- Polymers can be classified based on their source, thermal behavior, chemical structure, stereochemistry, and end use. Important types include thermoplastics, thermosets, homopolymers, copolymers, fibers, and plastics.
- Polymer properties depend on factors like strength, crystallinity, elasticity, and glass transition temperature which are influenced by the polymer structure. Common characterization techniques and molding processes like injection molding are also discussed.
This document provides an overview of polymer chemistry course content including synthesis of polymers, characterization of polymer molecules, molecular weight determination, and polymer structures. It discusses different types of polymers such as thermoplastics, thermosets, elastomers, and their properties. The key topics covered are polymerization reactions, molecular weight averages, polymer configurations including isotactic, syndiotactic and atactic, nomenclature, and the importance of molecular weight on polymer properties.
polymers include the familiar plastic and rubber materials, many of them are organic compounds that are chemically based on carbon ,hydrogen , and other nonmetallic elements , furthermore , they have very large molecular structure. these materials typically have low densities and maybe extremely flexible.
Polymers are large molecules formed by combining many small molecules called monomers. There are two main types of polymerization: addition and condensation. Addition polymers form without releasing any byproducts while condensation polymers form with the release of small molecules like water. Polymers can be classified based on their source, structure, and thermal properties. Common polymerization techniques include bulk, solution, suspension, and emulsion which depend on factors like physical state and reaction mechanism. Bulk polymerization involves only monomer and initiator while solution polymerization dissolves the monomer in a solvent.
Plastic is any of a wide range of synthetic or semi-synthetic materials that are moldable. Most plastics are derived from petrochemicals but some are partially natural. Plastics have a variety of properties including strength, flexibility, durability and the ability to be easily molded. There are two main types of plastics - thermoplastics, which soften when heated and can be reshaped, and thermosets, which cannot be reshaped after manufacture. Common plastics include polyvinyl chloride (PVC), polyethylene, and polypropylene, each with different chemical compositions and physical properties used in a wide range of applications.
Polymer - a long chain molecule made up of many small identical units of Monomer is known as Polymer.
Monomer - the smallest repeating unit is known as Monomer.
Polymer is a molecule is obtained by natural and synthetic origin having group of Smallest repeating unit is known as polymer.
Polymer is important for increasing the stability of drug molecule, it is important to influencing the solubility of drug molecule, it is important to maintain the Physicochemical properties, it is important to maintain the prolong stability of drug molecule in extended period of time, it is important for influencing the Bioavailability of drug.
Polymer is important for Pharmaceutical industries and research purpose.
The document discusses different types of polymer matrix composites, including thermoset and thermoplastic matrices. It covers various processing techniques for both such as hand layup, filament winding, injection molding. Key properties of the polymer matrix are outlined like protecting reinforcement, transferring load, impact resistance. Common reinforcements include glass, carbon fibers while resins often used are epoxy, polyester.
The document discusses different types of polymer matrix composites, including thermoset and thermoplastic matrices. It covers various processing techniques for composites such as hand layup, filament winding, and injection molding. Key topics include the properties and applications of polymer composites as well as the effects of temperature on thermoplastic polymers.
Polymer is a large molecule made of repeating structural units called monomers. The process of linking monomers together to form polymers is called polymerization. There are several ways to classify polymers, including by their origin (natural, synthetic, semisynthetic), structure (linear, branched, cross-linked), and mode of polymerization (addition, condensation). Common polymers include polyethylene, nylon, polyester, bakelite, and natural rubber.
Investigation of spatial configuration of Polypropylene and the influence of ...IOSR Journals
Abstract: Polypropylene is considered as one of the most important plastic types because of its substantial
supreme properties such as high melting temperature, good chemical resistance and desirable mechanical
properties, and achieving desired properties of Polypropylene is a significant activity, besides, gaining this
properties is the most important economical factor in reactor polymerization which gives a considerable curve
for performance cost polypropylene. In this paper, polypropylene properties, finding physical factor_ the form,
and other factors such as molecular weight _ the type of used catalyst and molecular mass which would be
expanded to properties of final polypropylene application, are all described. The state of mechanical changes
_thermal and photic changes of polymer which are closely dependant to foresaid factors_ is also discussed in
present paper, and this indicates the path toward achieving desired quality. Keyword: Polypropylene ¸ Stereo specificity Stereochemistry ،Ziegler-Natta catalysts، Atacticity
Methods of polymerisation It is also called as Zeigler – Natta polymerisation.
Zeigler (1953) and Natta (1955) discovered that in the presence of a combination of transition metal halides like TCl4, ZnBr3 etc, with an organometallic compound like triethyl-aluminium or trimethyl-aluminium, stereospecific polymerisation can be carried out.
Combination of metal halides and organometallic compounds are called Zeigler Natta catalyst.
11. Properties of Liquid Fuels in Energy Engineering.pdfHafizMudaserAhmad
The document discusses various properties of petroleum products that are important for evaluating and characterizing feedstocks for refining. It describes elemental analysis, density, viscosity, vapor pressure, flash point, fire point, autoignition temperature, cloud point, pour point, freezing point, smoke point, aniline point, diesel index, and octane number. Elemental analysis determines the percentages of carbon, hydrogen, oxygen, nitrogen, and sulfur, which provide indications of the feedstock character. Other properties like density, viscosity, vapor pressure etc. are important for determining suitable end uses and safety considerations for petroleum products.
Gaseous fuels are fuels that burn in their gaseous state and include natural gas, methane, propane, butane, and gases produced from coal, biomass, and industrial processes. They have advantages like being clean burning and easy to distribute through pipes but challenges with storage due to their gaseous state. Common gaseous fuels are classified into those found naturally like natural gas, those produced from solid fuels like producer gas, and those derived from petroleum like liquefied petroleum gas.
More Related Content
Similar to Lecture-Polymeric and Composite materials.ppt
- Polymers are giant molecules formed by linking together small repeating units called monomers via covalent bonds. There are three main types of polymerization: addition, condensation, and copolymerization.
- Properties of polymers depend on factors like the monomer type, the degree of polymerization, tacticity, and whether the polymer is crystalline or amorphous. Common polymers include polyethylene, polypropylene, nylon, polyethylene terephthalate.
- Natural rubbers are polymers of the monomer isoprene that provide flexibility and elasticity. However, natural rubber has limitations that are overcome through vulcanization, which introduces cross-links between polymer chains through the addition of sulfur.
Macromolecules are large molecules formed by linking many smaller units, or monomers, through covalent bonds. Natural substances like proteins and synthetic polymers are examples of macromolecules. Monomers undergo polymerization to form macromolecules by linking together through addition or condensation reactions. Polymers can be classified in different ways such as natural vs synthetic, organic vs inorganic, thermoplastic vs thermosetting, and linear, branched or cross-linked based on their molecular structure. The process of polymerization and properties of polymers depend on factors like the type of monomers, reaction conditions and molecular architecture.
Polymer science concerns large molecules called polymers that include rubbers, plastics, and fibers. Polymers are made of repeating molecular units and have high molecular weights. There are over 60,000 scientists working with polymers today to develop new materials with customized properties. Common polymers include polypropylene, polyethylene, and nylons. Polymers can be categorized based on their molecular structure as thermoplastics, thermosets, or elastomers, which determine how they respond to heat.
The document discusses various types of polymers including thermoplastics like polyethylene, polypropylene, polyvinyl chloride, polystyrene; thermosetting plastics; polymerization methods like addition, condensation and their mechanisms; classification of polymers; properties and applications of common polymers like polyethylene, polystyrene, polyvinyl chloride and teflon. It also discusses polymer structure, degree of polymerization, tactics and various additives used in plastics.
This document discusses polymer matrix composites, which consist of a polymer matrix combined with fibrous reinforcement. It describes the different types of polymer matrices - thermosetting and thermoplastic resins. Thermosetting resins like epoxy, polyester and phenolic polymers form cross-linked networks and do not melt when heated, while thermoplastic polymers like polyethylene, polypropylene and nylon soften when heated. The properties and uses of various thermosetting and thermoplastic resins are outlined. The role of the polymer matrix in a composite is also summarized - to hold fibers together, protect them, distribute loads evenly and enhance mechanical properties.
Polymerization is a process of reacting monomer molecules together to form polymer chains. There are two main types of polymerization:
1) Addition (chain) polymerization involves linking monomers together through double or triple bonds. It includes initiation, propagation, and termination steps.
2) Condensation (step-growth) polymerization combines monomers by removing a small molecule, like in polyester formation. It does not involve chain growth.
Condensation polymerization has a lower degree of polymerization and molecular weight increases slowly as functional groups are consumed in each step. In contrast, addition polymerization can achieve very high degrees of polymerization and molecular weight increases rapidly through successive monomer additions to growing chains.
This document provides an overview of polymers, including:
- Polymers are large molecules made by linking repeating units called monomers. Naturally occurring polymers have been used for thousands of years, while artificial polymers were developed more recently after WWII.
- Polymers can be classified based on their source, thermal behavior, chemical structure, stereochemistry, and end use. Important types include thermoplastics, thermosets, homopolymers, copolymers, fibers, and plastics.
- Polymer properties depend on factors like strength, crystallinity, elasticity, and glass transition temperature which are influenced by the polymer structure. Common characterization techniques and molding processes like injection molding are also discussed.
This document provides an overview of polymer chemistry course content including synthesis of polymers, characterization of polymer molecules, molecular weight determination, and polymer structures. It discusses different types of polymers such as thermoplastics, thermosets, elastomers, and their properties. The key topics covered are polymerization reactions, molecular weight averages, polymer configurations including isotactic, syndiotactic and atactic, nomenclature, and the importance of molecular weight on polymer properties.
polymers include the familiar plastic and rubber materials, many of them are organic compounds that are chemically based on carbon ,hydrogen , and other nonmetallic elements , furthermore , they have very large molecular structure. these materials typically have low densities and maybe extremely flexible.
Polymers are large molecules formed by combining many small molecules called monomers. There are two main types of polymerization: addition and condensation. Addition polymers form without releasing any byproducts while condensation polymers form with the release of small molecules like water. Polymers can be classified based on their source, structure, and thermal properties. Common polymerization techniques include bulk, solution, suspension, and emulsion which depend on factors like physical state and reaction mechanism. Bulk polymerization involves only monomer and initiator while solution polymerization dissolves the monomer in a solvent.
Plastic is any of a wide range of synthetic or semi-synthetic materials that are moldable. Most plastics are derived from petrochemicals but some are partially natural. Plastics have a variety of properties including strength, flexibility, durability and the ability to be easily molded. There are two main types of plastics - thermoplastics, which soften when heated and can be reshaped, and thermosets, which cannot be reshaped after manufacture. Common plastics include polyvinyl chloride (PVC), polyethylene, and polypropylene, each with different chemical compositions and physical properties used in a wide range of applications.
Polymer - a long chain molecule made up of many small identical units of Monomer is known as Polymer.
Monomer - the smallest repeating unit is known as Monomer.
Polymer is a molecule is obtained by natural and synthetic origin having group of Smallest repeating unit is known as polymer.
Polymer is important for increasing the stability of drug molecule, it is important to influencing the solubility of drug molecule, it is important to maintain the Physicochemical properties, it is important to maintain the prolong stability of drug molecule in extended period of time, it is important for influencing the Bioavailability of drug.
Polymer is important for Pharmaceutical industries and research purpose.
The document discusses different types of polymer matrix composites, including thermoset and thermoplastic matrices. It covers various processing techniques for both such as hand layup, filament winding, injection molding. Key properties of the polymer matrix are outlined like protecting reinforcement, transferring load, impact resistance. Common reinforcements include glass, carbon fibers while resins often used are epoxy, polyester.
The document discusses different types of polymer matrix composites, including thermoset and thermoplastic matrices. It covers various processing techniques for composites such as hand layup, filament winding, and injection molding. Key topics include the properties and applications of polymer composites as well as the effects of temperature on thermoplastic polymers.
Polymer is a large molecule made of repeating structural units called monomers. The process of linking monomers together to form polymers is called polymerization. There are several ways to classify polymers, including by their origin (natural, synthetic, semisynthetic), structure (linear, branched, cross-linked), and mode of polymerization (addition, condensation). Common polymers include polyethylene, nylon, polyester, bakelite, and natural rubber.
Investigation of spatial configuration of Polypropylene and the influence of ...IOSR Journals
Abstract: Polypropylene is considered as one of the most important plastic types because of its substantial
supreme properties such as high melting temperature, good chemical resistance and desirable mechanical
properties, and achieving desired properties of Polypropylene is a significant activity, besides, gaining this
properties is the most important economical factor in reactor polymerization which gives a considerable curve
for performance cost polypropylene. In this paper, polypropylene properties, finding physical factor_ the form,
and other factors such as molecular weight _ the type of used catalyst and molecular mass which would be
expanded to properties of final polypropylene application, are all described. The state of mechanical changes
_thermal and photic changes of polymer which are closely dependant to foresaid factors_ is also discussed in
present paper, and this indicates the path toward achieving desired quality. Keyword: Polypropylene ¸ Stereo specificity Stereochemistry ،Ziegler-Natta catalysts، Atacticity
Methods of polymerisation It is also called as Zeigler – Natta polymerisation.
Zeigler (1953) and Natta (1955) discovered that in the presence of a combination of transition metal halides like TCl4, ZnBr3 etc, with an organometallic compound like triethyl-aluminium or trimethyl-aluminium, stereospecific polymerisation can be carried out.
Combination of metal halides and organometallic compounds are called Zeigler Natta catalyst.
Similar to Lecture-Polymeric and Composite materials.ppt (20)
11. Properties of Liquid Fuels in Energy Engineering.pdfHafizMudaserAhmad
The document discusses various properties of petroleum products that are important for evaluating and characterizing feedstocks for refining. It describes elemental analysis, density, viscosity, vapor pressure, flash point, fire point, autoignition temperature, cloud point, pour point, freezing point, smoke point, aniline point, diesel index, and octane number. Elemental analysis determines the percentages of carbon, hydrogen, oxygen, nitrogen, and sulfur, which provide indications of the feedstock character. Other properties like density, viscosity, vapor pressure etc. are important for determining suitable end uses and safety considerations for petroleum products.
Gaseous fuels are fuels that burn in their gaseous state and include natural gas, methane, propane, butane, and gases produced from coal, biomass, and industrial processes. They have advantages like being clean burning and easy to distribute through pipes but challenges with storage due to their gaseous state. Common gaseous fuels are classified into those found naturally like natural gas, those produced from solid fuels like producer gas, and those derived from petroleum like liquefied petroleum gas.
This document outlines the course content for an Environmental Toxicology course. It includes an introduction to different areas of toxicology like mechanistic, descriptive, and regulatory toxicology. It also provides classifications of toxic agents and general characteristics of the toxic response. The course will cover topics such as properties of toxic substances, dose-response relationships, thresholds, and risk management. Students will be assessed through exams, quizzes, assignments, and a final exam.
This document provides an outline for a course on environmental toxicology. It includes the instructor's contact information and an overview of topics to be covered such as classification of toxic substances, dose-response relationships, water and soil pollutants, and examples of air pollutants. Assessment will include a midterm, quizzes, assignments, and a final exam. Lecture topics include exposure to toxicants in various settings and types of pollutants like air, water, and soil contaminants as well as occupational toxicants.
This document provides information about a course in Environmental Toxicology taught by Hafiz Mudaser Ahmad at the University of Engineering & Technology in Lahore, Pakistan. The course covers topics such as classification of toxic substances, dose-response relationships, and classes of toxicants including metals, agricultural chemicals, and food additives. Assessment includes a midterm exam, quizzes, assignments, and a final exam. The lecture outline discusses types of metals, treatment of metal poisoning, history of pesticide use, and classes of toxic metals, agricultural chemicals, and their toxic mechanisms and targets in the body.
Gas Power Cycles in Chemical Engineering Thermodynamics.pptHafizMudaserAhmad
This document describes several gas power cycles including ideal cycles like the Otto cycle, Diesel cycle, and Brayton cycle as well as actual engine cycles. It provides details on the assumptions and processes of each ideal cycle. The Otto cycle involves four internally reversible processes including isentropic compression and expansion with constant-volume heat addition and rejection. The Diesel cycle similarly involves isentropic compression and expansion but with constant-pressure rather than constant-volume heat addition. The Brayton cycle models gas turbine engines with isentropic compression and expansion and constant-pressure heat transfer. Regeneration and intercooling are discussed as ways to improve upon actual engine cycles.
carnot cycle (a theoretical thermodynamic cycle).pptHafizMudaserAhmad
The Carnot cycle, a theoretical thermodynamic cycle, serves as a fundamental concept in the study of heat engines. Named after the French physicist Sadi Carnot, this cycle provides insight into the maximum efficiency achievable by any heat engine operating between two temperature reservoirs. It consists of four reversible processes: isothermal expansion, adiabatic expansion, isothermal compression, and adiabatic compression. During the isothermal expansion process, the working substance (often a gas) absorbs heat from a high-temperature reservoir, expanding and doing work on the surroundings. The adiabatic expansion follows, during which the gas continues to expand without heat exchange, resulting in a decrease in temperature and pressure. Subsequently, the isothermal compression occurs as the gas is brought into contact with a low-temperature reservoir, releasing heat and contracting. Finally, the adiabatic compression completes the cycle as the gas is compressed without heat exchange, leading to an increase in temperature and pressure. The efficiency of the Carnot cycle depends solely on the temperatures of the reservoirs, with the maximum efficiency achievable when operating between two reversible isothermal processes. Despite being an idealized model, the Carnot cycle provides valuable insights into the principles of thermodynamics and serves as a benchmark for real-world heat engines.
This document discusses corrosion and its types. It begins by explaining that corrosion can manifest in various ways from cosmetic issues to catastrophic failures. It then discusses uniform corrosion, where metal thins uniformly without localized attacks. Examples of uniform corrosion are provided. The document outlines factors that affect corrosion rates like environment, humidity, and pollutants. It then discusses galvanic corrosion that occurs when two dissimilar metals contact each other in an electrolyte. The mechanism of both uniform and galvanic corrosion is explained. Finally, the document discusses how to apply the principles of galvanic corrosion.
Refractories are heat-resistant materials used to line furnaces and withstand high temperatures. Furnaces are used to melt metals and change their shape and properties. Refractories must withstand high heat, molten materials, gases, and stresses. Their key properties include melting point, density, porosity, strength, and thermal conductivity. Common refractory types include fireclay, high alumina, silica, magnesite, chromite, and zirconia. The right refractory must match the furnace type, materials, temperatures, stresses, and chemical compatibility. Proper refractory selection is crucial for furnace performance and longevity.
Literature Review Basics and Understanding Reference Management.pptxDr Ramhari Poudyal
Three-day training on academic research focuses on analytical tools at United Technical College, supported by the University Grant Commission, Nepal. 24-26 May 2024
Electric vehicle and photovoltaic advanced roles in enhancing the financial p...IJECEIAES
Climate change's impact on the planet forced the United Nations and governments to promote green energies and electric transportation. The deployments of photovoltaic (PV) and electric vehicle (EV) systems gained stronger momentum due to their numerous advantages over fossil fuel types. The advantages go beyond sustainability to reach financial support and stability. The work in this paper introduces the hybrid system between PV and EV to support industrial and commercial plants. This paper covers the theoretical framework of the proposed hybrid system including the required equation to complete the cost analysis when PV and EV are present. In addition, the proposed design diagram which sets the priorities and requirements of the system is presented. The proposed approach allows setup to advance their power stability, especially during power outages. The presented information supports researchers and plant owners to complete the necessary analysis while promoting the deployment of clean energy. The result of a case study that represents a dairy milk farmer supports the theoretical works and highlights its advanced benefits to existing plants. The short return on investment of the proposed approach supports the paper's novelty approach for the sustainable electrical system. In addition, the proposed system allows for an isolated power setup without the need for a transmission line which enhances the safety of the electrical network
Introduction- e - waste – definition - sources of e-waste– hazardous substances in e-waste - effects of e-waste on environment and human health- need for e-waste management– e-waste handling rules - waste minimization techniques for managing e-waste – recycling of e-waste - disposal treatment methods of e- waste – mechanism of extraction of precious metal from leaching solution-global Scenario of E-waste – E-waste in India- case studies.
A review on techniques and modelling methodologies used for checking electrom...nooriasukmaningtyas
The proper function of the integrated circuit (IC) in an inhibiting electromagnetic environment has always been a serious concern throughout the decades of revolution in the world of electronics, from disjunct devices to today’s integrated circuit technology, where billions of transistors are combined on a single chip. The automotive industry and smart vehicles in particular, are confronting design issues such as being prone to electromagnetic interference (EMI). Electronic control devices calculate incorrect outputs because of EMI and sensors give misleading values which can prove fatal in case of automotives. In this paper, the authors have non exhaustively tried to review research work concerned with the investigation of EMI in ICs and prediction of this EMI using various modelling methodologies and measurement setups.
Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapte...University of Maribor
Slides from talk presenting:
Aleš Zamuda: Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapter and Networking.
Presentation at IcETRAN 2024 session:
"Inter-Society Networking Panel GRSS/MTT-S/CIS
Panel Session: Promoting Connection and Cooperation"
IEEE Slovenia GRSS
IEEE Serbia and Montenegro MTT-S
IEEE Slovenia CIS
11TH INTERNATIONAL CONFERENCE ON ELECTRICAL, ELECTRONIC AND COMPUTING ENGINEERING
3-6 June 2024, Niš, Serbia
International Conference on NLP, Artificial Intelligence, Machine Learning an...gerogepatton
International Conference on NLP, Artificial Intelligence, Machine Learning and Applications (NLAIM 2024) offers a premier global platform for exchanging insights and findings in the theory, methodology, and applications of NLP, Artificial Intelligence, Machine Learning, and their applications. The conference seeks substantial contributions across all key domains of NLP, Artificial Intelligence, Machine Learning, and their practical applications, aiming to foster both theoretical advancements and real-world implementations. With a focus on facilitating collaboration between researchers and practitioners from academia and industry, the conference serves as a nexus for sharing the latest developments in the field.
Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
2. POLYMERS AND
COMPOSITE MATERIALS
1. Fundamentals of Polymer Technology
2. Thermoplastic Polymers
3. Thermosetting Polymers
4. Elastomers
5. Composites--Technology and Classification
6. Composite Materials
7. Guide to the Processing of Polymers and Composite
Materials
3. Polymer
A compound consisting of long-chain molecules, each
molecule made up of repeating units connected
together
There may be thousands, even millions of units in a
single polymer molecule
The word polymer is derived from the Greek words
poly, meaning many, and meros (reduced to mer),
meaning part
Most polymers are based on carbon and are
therefore considered organic chemicals
4. Types of Polymers
Polymers can be separated into plastics and rubbers
As engineering materials, it is appropriate to divide
them into the following three categories:
1. Thermoplastic polymers
2. Thermosetting polymers
3. Elastomers
where (1) and (2) are plastics and (3) are rubbers
5. Thermoplastic Polymers - Thermoplastics
Solid materials at room temperature but viscous liquids
when heated to temperatures of only a few hundred
degrees
This characteristic allows them to be easily and
economically shaped into products
They can be subjected to heating and cooling cycles
repeatedly without significant degradation
Symbolized by TP
6. Thermosetting Polymers - Thermosets
Cannot tolerate repeated heating cycles as
thermoplastics can
When initially heated, they soften and flow for
molding
Elevated temperatures also produce a chemical
reaction that hardens the material into an
infusible solid
If reheated, thermosets degrade and char rather
than soften
Symbolized by TS
7. Elastomers (Rubbers)
Polymers that exhibit extreme elastic extensibility when
subjected to relatively low mechanical stress
Some elastomers can be stretched by a factor of 10
and yet completely recover to their original shape
Although their properties are quite different from
thermosets, they share a similar molecular structure
that is different from the thermoplastics
8. Market Shares
Thermoplastics are commercially the most important
of the three types
About 70% of the tonnage of all synthetic
polymers produced
Thermosets and elastomers share the remaining
30%
On a volumetric basis, the current annual usage of
polymers exceeds that of metals
9. Examples of Polymers
Thermoplastics:
Polyethylene, polyvinylchloride, polypropylene,
polystyrene, and nylon
Thermosets:
Phenolics, epoxies, and certain polyesters
Elastomers:
Natural rubber (vulcanized)
Synthetic rubbers, which exceed the tonnage of
natural rubber
10. Reasons Why Polymers are Important
Plastics can be molded into intricate part shapes,
usually with no further processing
Very compatible with net shape processing
On a volumetric basis, polymers:
Are cost competitive with metals
Generally, require less energy to produce than
metals
Certain plastics are transparent, which makes them
competitive with glass in some applications
11. General Properties of Polymers
Low density relative to metals and ceramics
Good strength-to-weight ratios for certain (but not all)
polymers
High corrosion resistance
Low electrical and thermal conductivity
12. Limitations of Polymers
Low strength relative to metals and ceramics
Low modulus of elasticity (stiffness)
Service temperatures are limited to only a few
hundred degrees
Viscoelastic properties, which can be a distinct
limitation in load-bearing applications
Some polymers degrade when subjected to sunlight
and other forms of radiation
13. Synthesis of Polymers
Nearly all polymers used in engineering are synthetic
They are made by chemical processing
Polymers are synthesized by joining many small
molecules together into very large molecules, called
macromolecules, that possess a chain-like structure
The small units, called monomers, are generally
simple unsaturated organic molecules such as
ethylene C2H4
14. Polyethylene
Synthesis of polyethylene from ethylene monomers:
(1) n ethylene monomers, (2a) polyethylene of chain
length n; (2b) concise notation for depicting polymer
structure of chain length n
15. Polymerization
As a chemical process, the synthesis of polymers
can occur by either of two methods:
1. Addition polymerization
2. Step polymerization
Production of a given polymer is generally
associated with one method or the other
16. Addition Polymerization
In this process, the double bonds between carbon
atoms in the ethylene monomers are induced to open
up so they can join with other monomer molecules
The connections occur on both ends of the
expanding macromolecule, developing long chains of
repeating mers
It is initiated using a chemical catalyst to open the
carbon double bond in some of the monomers
17. Addition Polymerization
Model of addition (chain) polymerization: (1) initiation,
(2) rapid addition of monomers, and (3) resulting long
chain polymer molecule with n mers at termination of
reaction
18. Step Polymerization
In this form of polymerization, two reacting monomers
are brought together to form a new molecule of the
desired compound
As reaction continues, more reactant molecules
combine with the molecules first synthesized to form
polymers of length n = 2, then length n = 3, and so on
In addition, polymers of length n1 and n2 also
combine to form molecules of length n = n1 + n2, so
that two types of reactions are proceeding
simultaneously
19. Step Polymerization
Model of step polymerization showing the two types
of reactions occurring: (left) n-mer attaching a single
monomer to form a (n+1)-mer; and (right) n1-mer
combining with n2-mer to form a (n1+n2)-mer.
20. Some Examples
Polymers produced by addition polymerization:
Polyethylene, polypropylene, polyvinylchloride,
polyisoprene
Polymers produced by step polymerization:
Nylon, polycarbonate, phenol formaldehyde
21. Degree of Polymerization
Since molecules in a given batch of polymerized
material vary in length, n for the batch is an average
The mean value of n is called the degree of
polymerization (DP) for the batch
DP affects the properties of the polymer
Higher DP increases mechanical strength but also
increases viscosity in the fluid state, which makes
processing more difficult
22. Molecular Weight
The sum of the molecular weights of the monomers
in the molecule
MW = n times the molecular weight of each
repeating unit
Since n varies for different molecules in a batch,
the molecular weight must be interpreted as an
average
24. Polymer Molecular Structures
Linear structure – chain-like structure
Characteristic of thermoplastic polymers
Branched structure – chain-like but with side
branches
Also found in thermoplastic polymers
Cross-linked structure
Loosely cross-linked, characteristic of
elastomers
Tightly cross-linked, characteristic of thermosets
26. Effect of Branching on Properties
Thermoplastic polymers always possess linear or
branched structures or a mixture of the two
Branches increases entanglement among the
molecules, which makes the polymer
Stronger in the solid state
More viscous at a given temperature in the
plastic or liquid state
27. Effect of Cross-Linking on Properties
Thermosets possess a high degree of cross-linking;
elastomers possess a low degree of cross-linking
Thermosets are hard and brittle, while elastomers are
elastic and resilient
Cross-linking causes the polymer to become
chemically set
The reaction cannot be reversed
The polymer structure is permanently changed;
if heated, it degrades or burns rather than melt
28. Crystallinity in Polymers
Both amorphous and crystalline structures are
possible, although the tendency to crystallize is much
less than for metals or non-glass ceramics
Not all polymers can form crystals
For those that can, the degree of crystallinity (the
proportion of crystallized material in the mass) is
always less than 100%
29. Crystalline Polymer Structure
Crystallized regions in a polymer: (a) long molecules
forming crystals randomly mixed in with the
amorphous material; and (b) folded chain lamella, the
typical form of a crystallized region
30. Crystallinity and Properties
As crystallinity is increased in a polymer
Density increases
Stiffness, strength, and toughness increases
Heat resistance increases
If the polymer is transparent in the amorphous
state, it becomes opaque when partially
crystallized
31. Low Density & High-Density Polyethylene
Polyethylene type Low density High density
Degree of crystallinity 55% 92%
Specific gravity 0.92 0.96
Modulus of elasticity 140 MPa
(20,000 lb/in2)
700 MPa
(100,000 lb/in2)
Melting temperature 115C
(239F)
135C
(275F)
32. Some Observations About Crystallization
Linear polymers consist of long molecules with
thousands of repeated mers
Crystallization involves folding back and forth of the
long chains upon themselves
The crystallized regions are called crystallites
Crystallites take the form of lamellae randomly mixed in
with amorphous material
A crystallized polymer is a two-phase system
Crystallites interspersed in an amorphous matrix
33. Factors for Crystallization
Slower cooling promotes crystal formation and
growth
Mechanical deformation, as in the stretching of a
heated thermoplastic, tends to align the structure and
increase crystallization
Plasticizers (chemicals added to a polymer to soften
it) reduce crystallinity
34. Thermal Behavior of Polymers
Specific volume
(density)-1 as a
function of
temperature
35. Additives
Properties of a polymer can often be beneficially
changed by combining it with additives
Additives either alter the molecular structure or
Add a second phase, in effect transforming the
polymer into a composite material
36. Types of Additives by Function
Fillers – strengthen polymer or reduce cost
Plasticizers – soften polymer and improve flow
Colorants – pigments or dyes
Lubricants – reduce friction and improve flow
Flame retardents – reduce flammability of polymer
Cross-linking agents – for thermosets and elastomers
Ultraviolet light absorbers – reduce degradation from
sunlight
Antioxidants – reduce oxidation damage
37. Thermoplastic Polymers (TP)
Thermoplastic polymers can be heated from solid state
to viscous liquid and then cooled back down to solid
Heating and cooling can be repeated many times
without degrading the polymer
Reason: TP polymers consist of linear and/or
branched macromolecules that do not cross-link
upon heating
Thermosets and elastomers change chemically when
heated, which cross-links their molecules and
permanently sets these polymers
38. Mechanical Properties of Thermoplastics
Low modulus of elasticity (stiffness)
E is much lower than metals and ceramics
Low tensile strength
TS is about 10% of metal
Much lower hardness than metals or ceramics
Greater ductility on average
Tremendous range of values, from 1% elongation
for polystyrene to 500% or more for polypropylene
40. Physical Properties of Thermoplastics
Lower densities than metals or ceramics
Typical specific gravity for polymers are 1.2
(compared to ceramics (~ 2.5) and metals (~ 7)
Much higher coefficient of thermal expansion
Roughly five times the value for metals and 10
times the value for ceramics
Much lower melting temperatures
Insulating electrical properties
41. Commercial Thermoplastic
Products and Raw Materials
Thermoplastic products include
Molded and extruded items
Fibers and filaments
Films and sheets
Packaging materials
Paints and varnishes
Starting plastic materials are normally supplied to the
fabricator in the form of powders or pellets in bags,
drums, or larger loads by truck or rail car
42. Thermosetting Polymers (TS)
TS polymers are distinguished by their highly
cross-linked three-dimensional, covalently-bonded
structure
Chemical reactions associated with cross-linking are
called curing or setting
In effect, formed part (e.g., pot handle, electrical
switch cover, etc.) becomes a large macromolecule
Always amorphous and exhibits no glass transition
temperature
43. General Properties of Thermosets
Rigid - modulus of elasticity is two to three times
greater than thermoplastics
Brittle, virtually no ductility
Less soluble in common solvents than thermoplastics
Capable of higher service temperatures than
thermoplastics
Cannot be remelted - instead they degrade or burn
44. Cross-Linking in TS Polymers
Three categories:
1. Temperature-activated systems
2. Catalyst-activated systems
3. Mixing-activated systems
Curing is accomplished at the fabrication plants that
make the parts rather than the chemical plants that
supply the starting materials to the fabricator
45. Temperature-Activated Systems
Curing caused by heat supplied during part shaping
operation (e.g., molding)
Starting material is a linear polymer in granular form
supplied by the chemical plant
As heat is added, material softens for molding,
but continued heating causes cross-linking
Most common TS systems
The term “thermoset" applies best to these
polymers
46. Catalyst-Activated Systems
Cross-linking occurs when small amounts of a catalyst
are added to the polymer, which is in liquid form
Without the catalyst, the polymer remains stable and
liquid
Once combined with the catalyst it cures and
changes into solid form
47. Mixing-Activated Systems
Mixing of two chemicals results in a reaction that forms
a cross-linked solid polymer
Elevated temperatures are sometimes used to
accelerate the reactions
Most epoxies are examples of these systems
48. TS vs. TP Polymers
TS plastics are not as widely used as the TP
One reason is the added processing costs and
complications involved in curing
Largest market share of TS = phenolic resins with
6% of the total plastics market
Compare polyethylene with 35% market share
TS Products: countertops, plywood adhesives,
paints, molded parts, printed circuit boards and other
fiber reinforced plastics
49. Elastomers
Polymers capable of large elastic deformation when
subjected to relatively low stresses
Some can be extended 500% or more and still
return to their original shape
Two categories:
1. Natural rubber - derived from biological plants
2. Synthetic polymers - produced by
polymerization processes like those used for
thermoplastic and thermosetting polymers
50. Characteristics of Elastomers
Elastomers consist of long-chain molecules that are
cross-linked (like thermosetting polymers)
They owe their impressive elastic properties to two
features:
1. Molecules are tightly kinked when unstretched
2. Degree of cross-linking is substantially less
than thermosets
51. Elastomer Molecules
Model of long elastomer molecules, with low degree
of cross-linking: (left) unstretched, and (right) under
tensile stress
52. Elastic Behavior of Elastomer Molecule
When stretched, the molecules are forced to uncoil
and straighten
Natural resistance to uncoiling provides the initial
elastic modulus of the aggregate material
Under further strain, the covalent bonds of the
cross-linked molecules begin to play an increasing
role in the modulus, and stiffness increases
With greater cross-linking, the elastomer becomes
stiffer, and its modulus of elasticity is more linear
53. Stiffness of Rubber
Increase in stiffness as a function of strain for three
grades of rubber: natural rubber, vulcanized rubber,
and hard rubber
54. Vulcanization
Curing to cross-link most elastomers
Vulcanization = the term for curing in the context of
natural rubber (and certain synthetic rubbers)
Typical cross-linking in rubber is one to ten links per
hundred carbon atoms in the linear polymer chain,
depending on degree of stiffness desired
Considerably less than cross-linking in
thermosets
55. Natural Rubber (NR)
NR = polyisoprene, a high molecular-weight polymer
of isoprene (C5H8)
It is derived from latex, a milky substance produced
by various plants, most important of which is the
rubber tree that grows in tropical climates
Latex is a water emulsion of polyisoprene (about 1/3
by weight), plus various other ingredients
Rubber is extracted from latex by various methods
that remove the water
56. Vulcanized Natural Rubber
Properties: High tensile strength, tear strength,
resilience (capacity to recover shape), and resistance
to wear and fatigue
Weaknesses: degrades when subjected to heat,
sunlight, oxygen, ozone, and oil
Some of these limitations can be reduced by
additives
Market share of NR 22% of total rubber volume
(natural plus synthetic)
57. Natural Rubber Products
Largest single market for NR is automotive tires
Other products: shoe soles, bushings, seals, and
shock absorbing components
In tires, carbon black is an important additive
It reinforces the rubber, serving to increase tensile
strength and resistance to tear and abrasion
Other additives: clay, kaolin, silica, talc, and calcium
carbonate, as well as chemicals that accelerate and
promote vulcanization
58. Synthetic Rubbers
Development of synthetic rubbers was motivated
largely by world wars when NR was difficult to obtain
Tonnage of synthetic rubbers is now more than three
times that of NR
The most important synthetic rubber is
styrene-butadiene rubber (SBR), a copolymer of
butadiene (C4H6) and styrene (C8H8)
As with most other polymers, the main raw material
for synthetic rubbers is petroleum
59. Thermoplastic Elastomers (TPE)
A thermoplastic that behaves like an elastomer
Elastomeric properties not from chemical cross-links,
but from physical connections between soft and hard
phases in the material
Cannot match conventional elastomers in elevated
temperature, strength and creep resistance
Products: footwear; rubber bands; extruded tubing,
wire coating; molded automotive parts, but no tires
60. COMPOSITE MATERIALS
1. Technology and Classification of Composite
Materials
2. Metal Matrix Composites
3. Ceramic Matrix Composites
4. Polymer Matrix Composites
5. Guide to Processing Composite Materials
61. Composite Material Defined
A materials system composed of two or more distinct
phases whose combination produces aggregate
properties different from those of its constituents
Examples:
Cemented carbides
Plastic molding compounds with fillers
Rubber mixed with carbon black
Wood (a natural composite as distinguished from
a synthesized composite)
62. Why Composites are Important
Composites can be very strong and stiff, yet very light in
weight
Strength-to-weight and stiffness-to-weight ratios
are several times greater than steel or aluminum
Fatigue properties are generally better than for common
engineering metals
Toughness is often greater
Possible to achieve combinations of properties not
attainable with metals, ceramics, or polymers alone
63. Disadvantages and Limitations
Properties of many important composites are
anisotropic
May be an advantage or a disadvantage
Many polymer-based composites are subject to attack
by chemicals or solvents
Just as the polymers themselves are susceptible
Composite materials are generally expensive
Manufacturing methods for shaping composite materials
are often slow and costly
64. Possible Classification of Composites
1. Traditional composites – composite materials that
occur in nature or have been produced by
civilizations for many years
Examples: wood, concrete, asphalt
2. Synthetic composites - modern material systems
normally associated with the manufacturing
industries
Components are first produced separately and
then combined to achieve the desired
structure, properties, and part geometry
65. Components in a Composite Material
Most composite materials consist of two phases:
1. Primary phase - forms the matrix within which the
secondary phase is imbedded
2. Secondary phase - imbedded phase sometimes
referred to as a reinforcing agent, because it usually
strengthens the composite material
The reinforcing phase may be in the form of
fibers, particles, or various other geometries
66. Classification of Composite Materials
1. Metal Matrix Composites (MMCs) - mixtures of
ceramics and metals, such as cemented carbides
2. Ceramic Matrix Composites (CMCs) - Al2O3 and SiC
imbedded with fibers to improve properties
3. Polymer Matrix Composites (PMCs) - polymer resins
imbedded with filler or reinforcing agent
Examples: epoxy and polyester with fiber
reinforcement, and phenolic with powders
67. Functions of the Matrix Material
Primary phase provides the bulk form of the part or
product made of the composite material
Holds the imbedded phase in place, usually
enclosing and often concealing it
When a load is applied, the matrix shares the load
with the secondary phase, in some cases deforming
so that the stress is essentially born by the
reinforcing agent
68. Reinforcing Phase
Function is to reinforce the primary phase
Reinforcing phase (imbedded in the matrix) is most
commonly one of the following shapes: fibers,
particles, or flakes
69. Physical Shapes of Imbedded Phase
Possible physical shapes of imbedded phases in
composite materials: (a) fiber, (b) particle, and (c)
flake
70. Fibers
Filaments of reinforcing material, usually circular in
cross section
Diameters from ~ 0.0025 mm to about 0.13 mm
Filaments provide greatest opportunity for strength
enhancement of composites
Filament form of most materials is significantly
stronger than the bulk form
As diameter is reduced, the material becomes
oriented in the fiber axis direction and probability
of defects in the structure decreases significantly
71. Continuous Fibers vs.
Discontinuous Fibers
Continuous fibers - very long; in theory, they offer a
continuous path by which a load can be carried by
the composite part
Discontinuous fibers (chopped sections of continuous
fibers) - short lengths (L/D = roughly 100)
Whiskers = discontinuous fibers of hair-like
single crystals with diameters down to about
0.001 mm (0.00004 in) and very high strength
72. Fiber Orientation – Three Cases
One-dimensional reinforcement, in which maximum
strength and stiffness are obtained in the direction of
the fiber
Planar reinforcement, in some cases in the form of a
two-dimensional woven fabric
Random or three-dimensional in which the composite
material tends to possess isotropic properties
73. Fiber Orientation
Fiber orientation in composite materials: (a)
one-dimensional, continuous fibers; (b) planar,
continuous fibers in the form of a woven fabric; and (c)
random, discontinuous fibers
74. Materials for Fibers
Fiber materials in fiber-reinforced composites
Glass – most widely used filament
Carbon – high elastic modulus
Boron – very high elastic modulus
Polymers - Kevlar
Ceramics – SiC and Al2O3
Metals - steel
Most important commercial use of fibers is in polymer
composites
75. Particles and Flakes
A second common shape of imbedded phase is
particulate, ranging in size from microscopic to
macroscopic
Flakes are basically two-dimensional
particles - small flat platelets
Distribution of particles in the matrix is random
Strength and other properties of the composite
material are usually isotropic
76. Interface between Constituent Phases in
Composite Material
For the composite to function, the phases must bond
where they join at the interface
Direct bonding between primary and secondary phases
77. Interphase
In some cases, a third ingredient must be added to
bond primary and secondary phases
Called an interphase, it is like an adhesive
79. Properties of
Composite Materials
In selecting a composite material, an optimum
combination of properties is often sought, rather than
one particular property
Example: fuselage and wings of an aircraft must
be lightweight, strong, stiff, and tough
Several fiber-reinforced polymers possess
these properties
Example: natural rubber alone is relatively weak
Adding carbon black increases its strength
80. Three Factors that Determine Properties
1. Materials used as component phases in the
composite
2. Geometric shapes of the constituents and resulting
structure of the composite system
3. How the phases interact with one another
81. Example: Fiber Reinforced Polymer
Model of fiber-reinforced
composite material
showing direction in
which elastic modulus is
being estimated by the
rule of mixtures
82. Example: Fiber Reinforced Polymer
(continued)
Stress-strain relationships
for the composite material
and its constituents
The fiber is stiff but brittle,
while the matrix
(commonly a polymer) is
soft but ductile
83. Variations in Strength and Stiffness
Variation in elastic modulus and tensile strength as
function of direction relative to longitudinal axis of
carbon fiber-reinforced epoxy composite
84. Importance of Geometric Shape: Fibers
Most materials have tensile strengths several times
greater as fibers than as bulk materials
By imbedding the fibers in a polymer matrix, a
composite material is obtained that avoids the
problems of fibers but utilizes their strengths
Matrix provides the bulk shape to protect the fiber
surfaces and resist buckling
When a load is applied, the low-strength matrix
deforms and distributes the stress to the
high-strength fibers
86. Laminar Composite Structure
Conventional laminar
structure - two or more
layers bonded together
in an integral piece
Example: plywood, in
which layers are the
same wood, but grains
oriented differently to
increase overall strength
87. Sandwich Structure: Foam Core
Relatively thick core of
low-density foam
bonded on both faces to
thin sheets of a different
material
88. Sandwich Structure:
Honeycomb Core
Alternative to foam
core
Foam or
honeycomb achieve
high ratios of
strength-to-weight
and
stiffness-to-weight
89. Other Laminar Composite Structures
FRPs - multi-layered, fiber-reinforced plastic panels for
aircraft, boat hulls, other products
Printed circuit boards - layers of reinforced copper and
plastic for electrical conductivity and insulation,
respectively
Snow skis - layers of metals, particle board, and
phenolic plastic
Windshield glass - two layers of glass on either side of
a sheet of tough plastic
90. Metal Matrix Composites (MMCs)
Metal matrix reinforced by a second phase
Reinforcing phases:
1. Particles of ceramic
These MMCs are commonly called cermets
2. Fibers of various materials
Other metals, ceramics, carbon, and boron
91. Cermets
MMC with ceramic contained in a metallic matrix
The ceramic often dominates the mixture, sometimes
up to 96% by volume
Bonding can be enhanced by slight solubility between
phases at elevated temperatures used in processing
Cermets can be subdivided into
1. Cemented carbides – most common
2. Oxide-based cermets – less common
92. Cemented Carbides
One or more carbide compounds bonded in a metallic
matrix
Common cemented carbides are based on tungsten
carbide (WC), titanium carbide (TiC), and chromium
carbide (Cr3C2)
Tantalum carbide (TaC) and others are less
common
Metallic binders: usually cobalt (Co) or nickel (Ni)
93. Photomicrograph (about 1500X) of cemented carbide
with 85% WC and 15% Co (photo courtesty of
Kennametal Inc.)
Cemented Carbide
94. Typical plot of
hardness and
transverse
rupture strength
as a function of
cobalt content
Cemented Carbide Properties
95. Applications of
Cemented Carbides
Tungsten carbide cermets (Co binder)
Cutting tools, wire drawing dies, rock drilling bits,
powder metal dies, indenters for hardness testers
Titanium carbide cermets (Ni binder)
Cutting tools; high temperature applications such as
gas-turbine nozzle vanes
Chromium carbide cermets (Ni binder)
Gage blocks, valve liners, spray nozzles
96. Ceramic Matrix Composites (CMCs)
Ceramic primary phase imbedded with a secondary
phase, usually consisting of fibers
Attractive properties of ceramics: high stiffness,
hardness, hot hardness, and compressive strength;
and relatively low density
Weaknesses of ceramics: low toughness and bulk
tensile strength, susceptibility to thermal cracking
CMCs represent an attempt to retain the desirable
properties of ceramics while compensating for their
weaknesses
97. Ceramic Matrix Composite
Photomicrograph (about 3000X) of fracture surface of
SiC whisker reinforced Al2O3 (photo courtesy of
Greenleaf Corp.)
98. Polymer Matrix Composites (PMCs)
Polymer primary phase in which a secondary phase is
imbedded as fibers, particles, or flakes
Commercially, PMCs are more important than MMCs
or CMCs
Examples: most plastic molding compounds,
rubber reinforced with carbon black, and
fiber-reinforced polymers (FRPs)
99. Fiber-Reinforced Polymers (FRPs)
PMC consisting of a polymer matrix imbedded with
high-strength fibers
Polymer matrix materials:
Usually, a thermosetting plastic such as
unsaturated polyester or epoxy
Can also be thermoplastic, such as nylons
(polyamides), polycarbonate, polystyrene, and
polyvinylchloride
Fiber reinforcement is widely used in rubber
products such as tires and conveyor belts
100. Fibers in PMCs
Various forms: discontinuous (chopped), continuous,
or woven as a fabric
Principal fiber materials in FRPs are glass, carbon,
and Kevlar 49
Less common fibers include boron, SiC, and
Al2O3, and steel
Glass (in particular E-glass) is the most common fiber
material in today's FRPs
Its use to reinforce plastics dates from around
1920
101. Common FRP Structures
Most widely used form of FRP is a laminar structure
Made by stacking and bonding thin layers of fiber
and polymer until desired thickness is obtained
By varying fiber orientation among layers, a
specified level of anisotropy in properties can be
achieved in the laminate
Applications: boat hulls, aircraft wing and fuselage
sections, automobile and truck body panels
102. FRP Properties
High strength-to-weight and modulus-to-weight ratios
A typical FRP weighs only about 1/5 as much as
steel
Yet strength and modulus are comparable in fiber
direction
Good fatigue strength
Good corrosion resistance, although polymers are
soluble in various chemicals
Low thermal expansion for many FRPs
103. FRP Applications
Aerospace – much of the structural weight of today’s
airplanes and helicopters consist of advanced FRPs
Example: Boeing 787
Automotive – some body panels for cars and truck cabs
Low-carbon sheet steel still widely used due to its
low cost and ease of processing
Sports and recreation
FRPs used for boat hulls since 1940s
Fishing rods, tennis rackets, golf club shafts,
helmets, skis, bows and arrows
104. Other Polymer Matrix Composites
Other PMCs contain particles, flakes, and short fibers
Called fillers when used in molding compounds
Two categories:
1. Reinforcing fillers – used to strengthen or
otherwise improve mechanical properties
2. Extenders – used to increase bulk strength and
reduce cost per unit weight, with little or no effect
on mechanical properties
105. Guide to Processing Composite Materials
The two phases are typically produced separately
before being combined into the composite part
Processing techniques to fabricate MMC and
CMC components are similar to those used for
powdered metals and ceramics
Molding processes are commonly used for
PMCs with particles and chopped fibers
Specialized processes have been developed for
FRPs
106. Guide to the
Processing of Polymers
Polymers are nearly always shaped in a heated,
highly plastic state
Common operations are extrusion and molding
Molding of thermosets is more complicated because
of cross-linking
Thermoplastics are easier to mold, and a greater
variety of molding operations are available
Rubber processing has a longer history than plastics,
and rubber industries are traditionally separated from
plastics industry, even though processing is similar