The document discusses a study that investigated the mechanical effects of aging and annealing on injection molded high density polyethylene (HDPE) samples. Short-term stress relaxation tests were performed on samples subjected to different aging times and annealing parameters. The results showed that aging time did not have a clear relationship with relaxed stress in non-annealed samples. Samples annealed for 1 hour showed more consistent relaxation behavior and higher modulus than those annealed for 30 minutes or non-annealed samples. Additional aging after annealing further relaxed samples annealed for 30 minutes but did not significantly impact those annealed for 1 hour.
Curing Methods and Their Effects on The Strength of ConcreteIJERA Editor
There are a lot of arguments on which method of curing concrete gives good strength. These different opinions results into this study, which aim at investigating the effects of different curing methods on the strength of concrete. Laboratory test was employed for this study. Normal concretes were prepared using specified mix ratio of 1:2:4 and 1:3:6. The cubes tested for compressive strength at 3, 7, 21, and 28 days of curing respectively using four curing methods namely immersion, sprinkling, polythene sheeting and sharp sand coating. Testing indicate that water immersion curing method as well as sprinkling (spraying ) methods of curing, provide better results than membrane (polythene sheeting) method of curing. While sharp sand gives least strength. The rate of drying was significant when the specimens were subjected to curing with polythene sheet method of curing. This thus hampered the hydration process and thus affected the compressive strength property of the hardened concrete. The overall findings of this study suggests that concrete should be cured by water immersion or spraying regularly to achieve a better compressive strength in concrete.
This document summarizes the results of a study that evaluated the effects of autoclaving on various properties of polymethyl methacrylate (PMMA) powder used for dentures. The study compared PMMA cured via conventional water bath versus autoclaving. Tests evaluated properties like transverse strength, hardness, surface roughness, tensile strength, water sorption, porosity, density, color stability and more. Statistical analysis found autoclaving significantly improved the transverse strength of PMMA compared to water bath curing. Autoclaving applied heat and pressure that may have altered the polymeric chains and enhanced strength.
This study experimentally investigated the effects of Millenium 21 internal curing admixture on the durability and strength of concrete. Compressive strength, carbonation, and water absorption tests were performed on conventionally cured and internally cured concrete specimens at various ages. The results showed that internally cured concrete specimens had higher compressive strength at 7, 28, and 120 days compared to conventionally cured specimens. Carbonation depth was also lower in internally cured specimens at 120 days. Additionally, internally cured specimens exhibited reduced water absorption compared to conventionally cured specimens, indicating improved durability. The findings demonstrate that internal curing with Millenium 21 can enhance long-term strength and durability of concrete.
Reuse of Hospital Plastic Waste in Concrete as a Partial Replacement of Coars...IRJET Journal
This document summarizes previous research on using hospital plastic waste as a partial replacement for coarse aggregate in concrete. Several studies found that replacing coarse aggregate with plastic aggregate decreases the compressive strength and density of concrete, but also provides a way to reuse plastic waste. This study aims to further examine the impact resistance of concrete containing hospital plastic aggregate. It reviews literature on using different types of plastic waste in concrete and concludes that while plastic aggregate can be used, more research is needed on properties like durability, ductility, and thermal properties when using hospital plastic specifically.
This study evaluated the durability and bonding characteristics of concrete with partial replacement of natural coarse aggregate with recycled plastic aggregate. Specimens were subjected to acid and sulfate attacks to measure durability. Results found the plastic aggregate concrete had lower weight loss and higher compressive strength than control mix after attacks. Bonding tests also found similar bonding stress between mixes. The study concluded plastic aggregate can improve concrete durability and its use supports sustainable construction.
This document reviews the friction and wear behavior of polytetrafluoroethylene (PTFE) and its composites. It discusses how adding filler materials like carbon, graphite, and glass fibers to PTFE improves its mechanical and thermal properties while slightly affecting the low coefficient of friction. The document summarizes several studies that examined the friction and wear resistance of PTFE composites using methods like pin-on-disc testing. The key findings are that filler materials increase PTFE's hardness and wear resistance while keeping its low friction, and that load has a stronger effect on PTFE composites' wear behavior than sliding velocity.
Improvement of Tensile Properties of Recycled Low-Density Polyethylene by Inc...Dr. Amarjeet Singh
Plastics are used in versatile applications including
automobile, packaging, piping and house goods, these huge
uses attribute in the consumption of the oil reserves and the
emerged waste harm the environment when it disposed
irregularly. Recycling of plastics is one of the realistic
solutions to the aforementioned problems and to reduce
production cost. However, the reduction in mechanical
properties of recycled plastics limit their use and thus
reinforced plastics become popular because of their high
mechanical, physical and thermal properties. The effects of
calcium carbonate content from 0 to 15 wt.% on the tensile
properties of recycled low-density polyethylene (RLDPE)
were tested, the addition of calcium carbonate particles up to
15 wt.% was found to enhance the tensile strength and
modulus of elasticity of RLDPE samples. Three calcium
carbonate particle sizes (80, 200 and 500 µm) were mixed
with RLDPE to investigate the effect of particles size on the
tensile properties of RLDPE, it was found that the addition of
small filler particles resulted in a noticeable improvement of
tensile strength and modulus of elasticity of RLDPE
compared with large filler particles. It was also observed that
the addition of stearic acid slightly improves tensile
properties of RLDPE which may be related to improvement
of the interfacial adhesion between the filler and RLDPE. The
crystallization temperature and the degree of crystallinity of
RLDPE were increased by the addition of 7.5 wt.% calcium
carbonate particles because they act as nucleating agents.
Curing Methods and Their Effects on The Strength of ConcreteIJERA Editor
There are a lot of arguments on which method of curing concrete gives good strength. These different opinions results into this study, which aim at investigating the effects of different curing methods on the strength of concrete. Laboratory test was employed for this study. Normal concretes were prepared using specified mix ratio of 1:2:4 and 1:3:6. The cubes tested for compressive strength at 3, 7, 21, and 28 days of curing respectively using four curing methods namely immersion, sprinkling, polythene sheeting and sharp sand coating. Testing indicate that water immersion curing method as well as sprinkling (spraying ) methods of curing, provide better results than membrane (polythene sheeting) method of curing. While sharp sand gives least strength. The rate of drying was significant when the specimens were subjected to curing with polythene sheet method of curing. This thus hampered the hydration process and thus affected the compressive strength property of the hardened concrete. The overall findings of this study suggests that concrete should be cured by water immersion or spraying regularly to achieve a better compressive strength in concrete.
This document summarizes the results of a study that evaluated the effects of autoclaving on various properties of polymethyl methacrylate (PMMA) powder used for dentures. The study compared PMMA cured via conventional water bath versus autoclaving. Tests evaluated properties like transverse strength, hardness, surface roughness, tensile strength, water sorption, porosity, density, color stability and more. Statistical analysis found autoclaving significantly improved the transverse strength of PMMA compared to water bath curing. Autoclaving applied heat and pressure that may have altered the polymeric chains and enhanced strength.
This study experimentally investigated the effects of Millenium 21 internal curing admixture on the durability and strength of concrete. Compressive strength, carbonation, and water absorption tests were performed on conventionally cured and internally cured concrete specimens at various ages. The results showed that internally cured concrete specimens had higher compressive strength at 7, 28, and 120 days compared to conventionally cured specimens. Carbonation depth was also lower in internally cured specimens at 120 days. Additionally, internally cured specimens exhibited reduced water absorption compared to conventionally cured specimens, indicating improved durability. The findings demonstrate that internal curing with Millenium 21 can enhance long-term strength and durability of concrete.
Reuse of Hospital Plastic Waste in Concrete as a Partial Replacement of Coars...IRJET Journal
This document summarizes previous research on using hospital plastic waste as a partial replacement for coarse aggregate in concrete. Several studies found that replacing coarse aggregate with plastic aggregate decreases the compressive strength and density of concrete, but also provides a way to reuse plastic waste. This study aims to further examine the impact resistance of concrete containing hospital plastic aggregate. It reviews literature on using different types of plastic waste in concrete and concludes that while plastic aggregate can be used, more research is needed on properties like durability, ductility, and thermal properties when using hospital plastic specifically.
This study evaluated the durability and bonding characteristics of concrete with partial replacement of natural coarse aggregate with recycled plastic aggregate. Specimens were subjected to acid and sulfate attacks to measure durability. Results found the plastic aggregate concrete had lower weight loss and higher compressive strength than control mix after attacks. Bonding tests also found similar bonding stress between mixes. The study concluded plastic aggregate can improve concrete durability and its use supports sustainable construction.
This document reviews the friction and wear behavior of polytetrafluoroethylene (PTFE) and its composites. It discusses how adding filler materials like carbon, graphite, and glass fibers to PTFE improves its mechanical and thermal properties while slightly affecting the low coefficient of friction. The document summarizes several studies that examined the friction and wear resistance of PTFE composites using methods like pin-on-disc testing. The key findings are that filler materials increase PTFE's hardness and wear resistance while keeping its low friction, and that load has a stronger effect on PTFE composites' wear behavior than sliding velocity.
Improvement of Tensile Properties of Recycled Low-Density Polyethylene by Inc...Dr. Amarjeet Singh
Plastics are used in versatile applications including
automobile, packaging, piping and house goods, these huge
uses attribute in the consumption of the oil reserves and the
emerged waste harm the environment when it disposed
irregularly. Recycling of plastics is one of the realistic
solutions to the aforementioned problems and to reduce
production cost. However, the reduction in mechanical
properties of recycled plastics limit their use and thus
reinforced plastics become popular because of their high
mechanical, physical and thermal properties. The effects of
calcium carbonate content from 0 to 15 wt.% on the tensile
properties of recycled low-density polyethylene (RLDPE)
were tested, the addition of calcium carbonate particles up to
15 wt.% was found to enhance the tensile strength and
modulus of elasticity of RLDPE samples. Three calcium
carbonate particle sizes (80, 200 and 500 µm) were mixed
with RLDPE to investigate the effect of particles size on the
tensile properties of RLDPE, it was found that the addition of
small filler particles resulted in a noticeable improvement of
tensile strength and modulus of elasticity of RLDPE
compared with large filler particles. It was also observed that
the addition of stearic acid slightly improves tensile
properties of RLDPE which may be related to improvement
of the interfacial adhesion between the filler and RLDPE. The
crystallization temperature and the degree of crystallinity of
RLDPE were increased by the addition of 7.5 wt.% calcium
carbonate particles because they act as nucleating agents.
Studies on the mechanical and sorption properties of anacardiumAlexander Decker
This document summarizes a study on blending polypropylene (PP) with purified cashew gum (PCG) and evaluating the mechanical and sorption properties of the blends. Various blend compositions of PP and PCG were prepared and tested for properties like density, water absorption, tensile strength, hardness, and impact strength. The results showed that incorporating PCG into PP generally decreased tensile strength and impact strength but increased hardness and water absorption. Blending PP with 10% PCG improved its modulus. The study demonstrated that blending PP with PCG induced biodegradability, providing a way to control pollution from discarded plastics.
The document compares the mechanical and physical properties of low density polyethylene (LDPE) thin films and sheets reinforced with graphene nanoparticles. LDPE/graphene thin films were produced via solution casting, while sheets were made by compression molding. Testing showed that the thin films had enhanced tensile strength, lower melt flow index, and higher thermal stability compared to sheets. The tensile strength of thin films increased by up to 160% with 1% graphene, while sheets increased by 70%. Melt flow index decreased more for thin films, indicating higher viscosity. Thin films also showed greater improvement in glass transition temperature. These results demonstrate that processing technique affects the properties of LDPE/graphene nanocomposites.
Mechanical Properties of Tere-Phthalic Unsaturated Polyester Resin Reinforced...IOSR Journals
Abstract: The objective of this work is to investigate the mechanical properties of particulate snail shell
reinforced unsaturated polyester composite. 5wt% ground snail shell of particle size 625microns was
introduced to unsaturated polyester matrix to produce a composite. Other specimens were produced at 10, 15,
20, 25 and 30 weight percentages of the particulate filler in unsaturated polyester matrix. Mechanical tests were
conducted on prepared samples of the composite material. The results showed that the flexural strength of the
composite with 20wt% snail shell particulate reinforcement was greatly enhanced and the impact and hardness
properties were greatly improved at 5wt% filler loading. The composite could be considered for applications in
areas where high impact strength is a requirement such as in shipping containers. The 20wt% snail shell
reinforced unsaturated polyester can be used in place of pure polyester for applications where flexibility is of
utmost importance. Keywords: Snail Shell, Unsaturated Polyester, Composite, Mechanical Properties, filler
Utilization of pulverized plastic in cement concrete as fine aggregateeSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Utilization of pulverized plastic in cement concrete as fine aggregateeSAT Journals
1. The study investigated utilizing pulverized plastic as a replacement for fine aggregate in cement concrete.
2. Plastic was collected and pulverized into granules with a density of 460 kg/m3 and specific gravity of 0.46.
3. Concrete cubes with 0%, 25%, 50%, 75%, and 100% replacement of sand with plastic were tested.
4. Results showed compressive strength decreased with higher plastic replacements but 25% replacement resulted in only a 3-3.2 N/mm2 decrease in strength at 7 days.
Moisture absorption and mechanical degradation studies of PMI foam cored fibe...IJERA Editor
The document summarizes a study on the effects of moisture absorption and temperature on the mechanical properties of polymethacrylimide (PMI) foam core sandwich composites. Specimens were immersed in deionized water and sea water at 25°C and 70°C. The results showed that specimens absorbed more moisture at higher temperatures and in deionized water compared to sea water. Exposure to high temperature (70°C) water significantly reduced the compressive and flexural strength and modulus of the composites, with strength reductions of up to 36% and modulus reductions of up to 68%, likely due to plasticization and fracturing of the PMI foam core at high temperatures. Specimens immersed in low
IRJET-Steel and Glass Fibre Reinforced Concrete: A ReviewIRJET Journal
1. Single crystals of disodium hydrogen phosphate (DSHP) were grown using a slow evaporation technique. Thermal analysis showed the crystals lose water below 131°C and undergo intermolecular condensation around 352°C.
2. Microhardness tests on the crystals found the hardness increases up to a load of 30g and remains constant at higher loads, indicating surface hardening.
3. Differential scanning calorimetry identified melting at 35.96°C and endothermic peaks corresponding to release of weakly absorbed and crystallization water, with all water released by 200°C.
Critical Literature Review on Improvement of Concrete Properties by Bacterial...IRJET Journal
This document provides a literature review of research on improving concrete properties using bacterial solutions. It summarizes 15 previous studies that investigated how adding various bacteria like Bacillus pasteurii and Bacillus subtilis to concrete affects mechanical properties and durability. The studies found that bacterial concrete has higher compressive strength, flexural strength, elastic modulus, and lower water absorption and permeability compared to normal concrete. The bacteria are able to precipitate calcium carbonate in concrete cracks, potentially providing a self-healing effect. Bacterial solutions from 105-107 cells/ml were found to be most effective. Using fly ash or slag cement along with bacterial solutions can further enhance concrete properties. Overall, the literature demonstrates that bacterial solutions have potential to
IRJET-Mechanical Properties of Self Curing Concrete Incorporating Polyethylen...IRJET Journal
This document discusses a study on the properties of self-curing concrete made with the addition of polyethylene glycol-600 (PEG-600). PEG-600 is used as a self-curing agent to provide internal curing and moisture retention within the concrete. Concrete specimens were cast containing 0.5%, 1%, 1.5%, and 2% PEG by weight of cement. The compressive strength, split tensile strength, flexural strength, and modulus of elasticity of the PEG concrete were tested and compared to conventionally cured concrete without PEG. The results aimed to determine the optimum percentage of PEG addition for improved mechanical properties of self-curing concrete.
TN_Resin Quality and Impact on Performance for HDPE Geomembranes_REV0515Sara Rahme
This technical document compares the properties of three HDPE resin samples used to produce geomembranes. Resin sample 3 performs the best, meeting or exceeding specifications for key properties like oxidative induction time and environmental stress crack resistance. Resins 1 and 2 have poorer properties, such as lower oxidative induction times and shorter environmental stress crack resistance times, meaning geomembranes produced from these resins would have shorter lifespans. The document emphasizes that resin quality strongly influences the performance and reliability of the final geomembrane product.
Properties of Glass Fibre Reinforced Geopolymer ConcreteIJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
International Journal of Modern Engineering Research (IJMER) covers all the fields of engineering and science: Electrical Engineering, Mechanical Engineering, Civil Engineering, Chemical Engineering, Computer Engineering, Agricultural Engineering, Aerospace Engineering, Thermodynamics, Structural Engineering, Control Engineering, Robotics, Mechatronics, Fluid Mechanics, Nanotechnology, Simulators, Web-based Learning, Remote Laboratories, Engineering Design Methods, Education Research, Students' Satisfaction and Motivation, Global Projects, and Assessment…. And many more.
Preparation and Characterization of Rubber Composites using Sawdust as Fillerijtsrd
The research work aims to prepare, characterize and apply the vulcanized rubber composites by using sawdust as filler. Sawdust was used as filler in the process of preparation of vulcanized rubber composites. The composite of natural rubber sawdust NR SD was prepared by being replaced the percent ratio 100 0 75 25 50 50 and 25 75 parts weight of natural rubber NR with SD vulcanized for rubbery goods. The surface morphology, elemental analysis and thermal degradation of the prepared NR SD composites were determined by SEM, EDXRF and TG DTA, respectively. The physic mechanical properties such as tensile strength tear strength, elongation at break, hardness and abrasive resistance of NR SD composites were determined by standard rubber testing methods. It was observed that the vulcanized NR SD composites were again determined by soaking in the selected organic solvents and oils ethanol, gasoline, diesel, engine oil, and used engine oil . Being used the sawdust as filler, it not only reduces the cost of production for appliances but also it is likely the supply of the maintenance for Green. Dr. Htoon Nay Oo ""Preparation and Characterization of Rubber Composites using Sawdust as Filler"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-4 , June 2019, URL: https://www.ijtsrd.com/papers/ijtsrd23683.pdf
Paper URL: https://www.ijtsrd.com/chemistry/other/23683/preparation-and-characterization-of--rubber-composites-using-sawdust-as-filler/dr-htoon-nay-oo
In below present, which I have presented in biomaterials class, I focused on the hashtag#fatigue behavior of hashtag#porous_metallic biomaterials and described the important factors on this behavior.
The document summarizes a study that investigated how adding glass flakes in concentrations of 5%, 10%, and 20% impacted the flexural and impact strength of denture base resins compared to an unmodified resin. Specimens were tested for flexural and impact strength based on ISO standards. Results showed flexural strength decreased with higher glass flake concentrations while impact strength was unchanged at 5% but decreased at 10% and 20%. The study concluded flexural and impact strength were lowest for the 20% glass flake modified resin group.
This document discusses the stereolithographic ceramic manufacturing (SLCM) process for producing bioactive glass ceramic structures. The SLCM process uses digital light processing to layer-by-layer print, debind, and sinter a bioactive glass ceramic slurry into dense 3D parts. Testing showed the bioactive glass ceramic parts produced using SLCM had a density of 2.7 g/cm3 and a high biaxial bending strength of 124 MPa, comparable to natural cortical bone. The homogeneous microstructure and low defect rate contributed to the high strength. The SLCM process enables the precise production of complex bioactive glass ceramic scaffolds and structures for applications in bone repair and replacement.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
PET BOTTLE WASTE AS A SUPPLEMENT TO CONCRETE FINE AGGREGATEIAEME Publication
Background/Objectives: Polyethelene terephthalate (PET) is a standout amongst the most well-known purchaser plastic utilized and is broadly utilized as crude material to items, for example, mineral water bottles, soda pop jugs, compartments for bundling of sustenance and other shopper products. Methods/Statistical Analysis: The goal of this paper to decide ideal quality and impact of utilization of reused PET as fractional substitution of fine total in common Portland bond. In this study Concrete with 0%, 5%.10%, 15% and 20% PET containers waste for fine total were delivered and contrasted against blend and no substitution or 0% substitution. Findings: The 3D square examples and shaft examples of 45 no of each were thrown, cured and tried for 7days and 28days quality. The pressure and flexural quality were done and results were contrasted and control example. In light of the examination a relationship for the forecast of compressive quality and flexural quality of cement containing waste PET as fine total substitution. Applications/Improvements: The consequences of this examination merge the possibility of the utilization of pet container waste in the field of development particularly in the plan of cement. The utilization of PET containers waste due to reduced and light weight and in turn lessens the unit cement weight. The auxiliary solid individual weight from a building diminishment will lead to reduction in building weight and reduce the seismic danger due to the earth shake drives directly reliant on the earth shudder strengths.
Synthesis of new dental nanocomposite with glass nanoparticles Article 7, Vol...Nanomedicine Journal (NMJ)
Objective(s):
The aim of this study was to synthesis new dental nanocomposites reinforced with fabricated glass nanoparticles and compare two methods for fabrication and investigate the effect of this filler on mechanical properties.
Materials and Methods: The glass nanoparticles were produced by wet milling process. The particle size and shape was achieved using PSA and SEM. Glass nanoparticles surface was modified with MPTMS silane. The composite was prepared by mixing these silane-treated nanoparticles with monomers. The resin composition was UDMA /TEGDMA (70/30 weight ratio). Three composites were developed with 5, 7.5 and 10 wt% glass fillers in each group. Two preparation methods were used, in dispersion in solvent method (group D) glass nanoparticles were sonically dispersed in acetone and the solution was added to resin, then acetone was evaporated. In non-dispersion in solvent method (group N) the glass nanoparticles were directly added to resin. Mechanical properties were investigated included flexural strength, flexural modulus and Vickers hardness.
Results:
Higher volume of glass nanoparticles improves mechanical properties of composite. Group D has batter mechanical properties than group N. Flexural strength of composite with 10%w filler of group D was 75Mpa against 59 Mpa of the composite with the same filler content of group N. The flexural modulus and hardness of group D is more than group N.
Conclusion:
It can be concluded that dispersion in solvent method is the best way to fabricate nanocomposites and glass nanoparticles is a significant filler to improve mechanical properties of dental nanocomposite.
Investigation of Deformation Analysis of Glass Fiber Reinforced Polymer Injec...Dr. Amarjeet Singh
Warpage is one of the most crucial problems in injection molded products. Factors affecting warpage include Material, Part geometry, gate location, Fiber content & orientation, temperature, etc. Since many factors cause shrinkage and warpage, it is very difficult to distinguish the predominant factor. In the present study, we have focused on contribution of fiber content on warpage of injection molded part. Basic requirement of the part is flatness at sealing area within given tolerance. The required flatness should be within a given tolerance for effective functioning of the component. Flow simulation software has been used to assess the effect of fiber content on warpage and in turn flatness of the component.
Karl Ziegler and Erhard Holzkamp invented high-density polyethylene (HDPE) in 1953 using catalysts and low pressure. HDPE was used for pipes starting in 1955 and has since been used for a variety of applications like toys, bottles, and wire insulation due to its toughness, flexibility, and chemical resistance. HDPE has advantages like low cost and impact resistance but also disadvantages like poor weathering resistance and flammability. It is a thermoplastic polymer composed of carbon and hydrogen atoms that can be processed using heat.
Studies on the mechanical and sorption properties of anacardiumAlexander Decker
This document summarizes a study on blending polypropylene (PP) with purified cashew gum (PCG) and evaluating the mechanical and sorption properties of the blends. Various blend compositions of PP and PCG were prepared and tested for properties like density, water absorption, tensile strength, hardness, and impact strength. The results showed that incorporating PCG into PP generally decreased tensile strength and impact strength but increased hardness and water absorption. Blending PP with 10% PCG improved its modulus. The study demonstrated that blending PP with PCG induced biodegradability, providing a way to control pollution from discarded plastics.
The document compares the mechanical and physical properties of low density polyethylene (LDPE) thin films and sheets reinforced with graphene nanoparticles. LDPE/graphene thin films were produced via solution casting, while sheets were made by compression molding. Testing showed that the thin films had enhanced tensile strength, lower melt flow index, and higher thermal stability compared to sheets. The tensile strength of thin films increased by up to 160% with 1% graphene, while sheets increased by 70%. Melt flow index decreased more for thin films, indicating higher viscosity. Thin films also showed greater improvement in glass transition temperature. These results demonstrate that processing technique affects the properties of LDPE/graphene nanocomposites.
Mechanical Properties of Tere-Phthalic Unsaturated Polyester Resin Reinforced...IOSR Journals
Abstract: The objective of this work is to investigate the mechanical properties of particulate snail shell
reinforced unsaturated polyester composite. 5wt% ground snail shell of particle size 625microns was
introduced to unsaturated polyester matrix to produce a composite. Other specimens were produced at 10, 15,
20, 25 and 30 weight percentages of the particulate filler in unsaturated polyester matrix. Mechanical tests were
conducted on prepared samples of the composite material. The results showed that the flexural strength of the
composite with 20wt% snail shell particulate reinforcement was greatly enhanced and the impact and hardness
properties were greatly improved at 5wt% filler loading. The composite could be considered for applications in
areas where high impact strength is a requirement such as in shipping containers. The 20wt% snail shell
reinforced unsaturated polyester can be used in place of pure polyester for applications where flexibility is of
utmost importance. Keywords: Snail Shell, Unsaturated Polyester, Composite, Mechanical Properties, filler
Utilization of pulverized plastic in cement concrete as fine aggregateeSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Utilization of pulverized plastic in cement concrete as fine aggregateeSAT Journals
1. The study investigated utilizing pulverized plastic as a replacement for fine aggregate in cement concrete.
2. Plastic was collected and pulverized into granules with a density of 460 kg/m3 and specific gravity of 0.46.
3. Concrete cubes with 0%, 25%, 50%, 75%, and 100% replacement of sand with plastic were tested.
4. Results showed compressive strength decreased with higher plastic replacements but 25% replacement resulted in only a 3-3.2 N/mm2 decrease in strength at 7 days.
Moisture absorption and mechanical degradation studies of PMI foam cored fibe...IJERA Editor
The document summarizes a study on the effects of moisture absorption and temperature on the mechanical properties of polymethacrylimide (PMI) foam core sandwich composites. Specimens were immersed in deionized water and sea water at 25°C and 70°C. The results showed that specimens absorbed more moisture at higher temperatures and in deionized water compared to sea water. Exposure to high temperature (70°C) water significantly reduced the compressive and flexural strength and modulus of the composites, with strength reductions of up to 36% and modulus reductions of up to 68%, likely due to plasticization and fracturing of the PMI foam core at high temperatures. Specimens immersed in low
IRJET-Steel and Glass Fibre Reinforced Concrete: A ReviewIRJET Journal
1. Single crystals of disodium hydrogen phosphate (DSHP) were grown using a slow evaporation technique. Thermal analysis showed the crystals lose water below 131°C and undergo intermolecular condensation around 352°C.
2. Microhardness tests on the crystals found the hardness increases up to a load of 30g and remains constant at higher loads, indicating surface hardening.
3. Differential scanning calorimetry identified melting at 35.96°C and endothermic peaks corresponding to release of weakly absorbed and crystallization water, with all water released by 200°C.
Critical Literature Review on Improvement of Concrete Properties by Bacterial...IRJET Journal
This document provides a literature review of research on improving concrete properties using bacterial solutions. It summarizes 15 previous studies that investigated how adding various bacteria like Bacillus pasteurii and Bacillus subtilis to concrete affects mechanical properties and durability. The studies found that bacterial concrete has higher compressive strength, flexural strength, elastic modulus, and lower water absorption and permeability compared to normal concrete. The bacteria are able to precipitate calcium carbonate in concrete cracks, potentially providing a self-healing effect. Bacterial solutions from 105-107 cells/ml were found to be most effective. Using fly ash or slag cement along with bacterial solutions can further enhance concrete properties. Overall, the literature demonstrates that bacterial solutions have potential to
IRJET-Mechanical Properties of Self Curing Concrete Incorporating Polyethylen...IRJET Journal
This document discusses a study on the properties of self-curing concrete made with the addition of polyethylene glycol-600 (PEG-600). PEG-600 is used as a self-curing agent to provide internal curing and moisture retention within the concrete. Concrete specimens were cast containing 0.5%, 1%, 1.5%, and 2% PEG by weight of cement. The compressive strength, split tensile strength, flexural strength, and modulus of elasticity of the PEG concrete were tested and compared to conventionally cured concrete without PEG. The results aimed to determine the optimum percentage of PEG addition for improved mechanical properties of self-curing concrete.
TN_Resin Quality and Impact on Performance for HDPE Geomembranes_REV0515Sara Rahme
This technical document compares the properties of three HDPE resin samples used to produce geomembranes. Resin sample 3 performs the best, meeting or exceeding specifications for key properties like oxidative induction time and environmental stress crack resistance. Resins 1 and 2 have poorer properties, such as lower oxidative induction times and shorter environmental stress crack resistance times, meaning geomembranes produced from these resins would have shorter lifespans. The document emphasizes that resin quality strongly influences the performance and reliability of the final geomembrane product.
Properties of Glass Fibre Reinforced Geopolymer ConcreteIJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
International Journal of Modern Engineering Research (IJMER) covers all the fields of engineering and science: Electrical Engineering, Mechanical Engineering, Civil Engineering, Chemical Engineering, Computer Engineering, Agricultural Engineering, Aerospace Engineering, Thermodynamics, Structural Engineering, Control Engineering, Robotics, Mechatronics, Fluid Mechanics, Nanotechnology, Simulators, Web-based Learning, Remote Laboratories, Engineering Design Methods, Education Research, Students' Satisfaction and Motivation, Global Projects, and Assessment…. And many more.
Preparation and Characterization of Rubber Composites using Sawdust as Fillerijtsrd
The research work aims to prepare, characterize and apply the vulcanized rubber composites by using sawdust as filler. Sawdust was used as filler in the process of preparation of vulcanized rubber composites. The composite of natural rubber sawdust NR SD was prepared by being replaced the percent ratio 100 0 75 25 50 50 and 25 75 parts weight of natural rubber NR with SD vulcanized for rubbery goods. The surface morphology, elemental analysis and thermal degradation of the prepared NR SD composites were determined by SEM, EDXRF and TG DTA, respectively. The physic mechanical properties such as tensile strength tear strength, elongation at break, hardness and abrasive resistance of NR SD composites were determined by standard rubber testing methods. It was observed that the vulcanized NR SD composites were again determined by soaking in the selected organic solvents and oils ethanol, gasoline, diesel, engine oil, and used engine oil . Being used the sawdust as filler, it not only reduces the cost of production for appliances but also it is likely the supply of the maintenance for Green. Dr. Htoon Nay Oo ""Preparation and Characterization of Rubber Composites using Sawdust as Filler"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-4 , June 2019, URL: https://www.ijtsrd.com/papers/ijtsrd23683.pdf
Paper URL: https://www.ijtsrd.com/chemistry/other/23683/preparation-and-characterization-of--rubber-composites-using-sawdust-as-filler/dr-htoon-nay-oo
In below present, which I have presented in biomaterials class, I focused on the hashtag#fatigue behavior of hashtag#porous_metallic biomaterials and described the important factors on this behavior.
The document summarizes a study that investigated how adding glass flakes in concentrations of 5%, 10%, and 20% impacted the flexural and impact strength of denture base resins compared to an unmodified resin. Specimens were tested for flexural and impact strength based on ISO standards. Results showed flexural strength decreased with higher glass flake concentrations while impact strength was unchanged at 5% but decreased at 10% and 20%. The study concluded flexural and impact strength were lowest for the 20% glass flake modified resin group.
This document discusses the stereolithographic ceramic manufacturing (SLCM) process for producing bioactive glass ceramic structures. The SLCM process uses digital light processing to layer-by-layer print, debind, and sinter a bioactive glass ceramic slurry into dense 3D parts. Testing showed the bioactive glass ceramic parts produced using SLCM had a density of 2.7 g/cm3 and a high biaxial bending strength of 124 MPa, comparable to natural cortical bone. The homogeneous microstructure and low defect rate contributed to the high strength. The SLCM process enables the precise production of complex bioactive glass ceramic scaffolds and structures for applications in bone repair and replacement.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
PET BOTTLE WASTE AS A SUPPLEMENT TO CONCRETE FINE AGGREGATEIAEME Publication
Background/Objectives: Polyethelene terephthalate (PET) is a standout amongst the most well-known purchaser plastic utilized and is broadly utilized as crude material to items, for example, mineral water bottles, soda pop jugs, compartments for bundling of sustenance and other shopper products. Methods/Statistical Analysis: The goal of this paper to decide ideal quality and impact of utilization of reused PET as fractional substitution of fine total in common Portland bond. In this study Concrete with 0%, 5%.10%, 15% and 20% PET containers waste for fine total were delivered and contrasted against blend and no substitution or 0% substitution. Findings: The 3D square examples and shaft examples of 45 no of each were thrown, cured and tried for 7days and 28days quality. The pressure and flexural quality were done and results were contrasted and control example. In light of the examination a relationship for the forecast of compressive quality and flexural quality of cement containing waste PET as fine total substitution. Applications/Improvements: The consequences of this examination merge the possibility of the utilization of pet container waste in the field of development particularly in the plan of cement. The utilization of PET containers waste due to reduced and light weight and in turn lessens the unit cement weight. The auxiliary solid individual weight from a building diminishment will lead to reduction in building weight and reduce the seismic danger due to the earth shake drives directly reliant on the earth shudder strengths.
Synthesis of new dental nanocomposite with glass nanoparticles Article 7, Vol...Nanomedicine Journal (NMJ)
Objective(s):
The aim of this study was to synthesis new dental nanocomposites reinforced with fabricated glass nanoparticles and compare two methods for fabrication and investigate the effect of this filler on mechanical properties.
Materials and Methods: The glass nanoparticles were produced by wet milling process. The particle size and shape was achieved using PSA and SEM. Glass nanoparticles surface was modified with MPTMS silane. The composite was prepared by mixing these silane-treated nanoparticles with monomers. The resin composition was UDMA /TEGDMA (70/30 weight ratio). Three composites were developed with 5, 7.5 and 10 wt% glass fillers in each group. Two preparation methods were used, in dispersion in solvent method (group D) glass nanoparticles were sonically dispersed in acetone and the solution was added to resin, then acetone was evaporated. In non-dispersion in solvent method (group N) the glass nanoparticles were directly added to resin. Mechanical properties were investigated included flexural strength, flexural modulus and Vickers hardness.
Results:
Higher volume of glass nanoparticles improves mechanical properties of composite. Group D has batter mechanical properties than group N. Flexural strength of composite with 10%w filler of group D was 75Mpa against 59 Mpa of the composite with the same filler content of group N. The flexural modulus and hardness of group D is more than group N.
Conclusion:
It can be concluded that dispersion in solvent method is the best way to fabricate nanocomposites and glass nanoparticles is a significant filler to improve mechanical properties of dental nanocomposite.
Investigation of Deformation Analysis of Glass Fiber Reinforced Polymer Injec...Dr. Amarjeet Singh
Warpage is one of the most crucial problems in injection molded products. Factors affecting warpage include Material, Part geometry, gate location, Fiber content & orientation, temperature, etc. Since many factors cause shrinkage and warpage, it is very difficult to distinguish the predominant factor. In the present study, we have focused on contribution of fiber content on warpage of injection molded part. Basic requirement of the part is flatness at sealing area within given tolerance. The required flatness should be within a given tolerance for effective functioning of the component. Flow simulation software has been used to assess the effect of fiber content on warpage and in turn flatness of the component.
Karl Ziegler and Erhard Holzkamp invented high-density polyethylene (HDPE) in 1953 using catalysts and low pressure. HDPE was used for pipes starting in 1955 and has since been used for a variety of applications like toys, bottles, and wire insulation due to its toughness, flexibility, and chemical resistance. HDPE has advantages like low cost and impact resistance but also disadvantages like poor weathering resistance and flammability. It is a thermoplastic polymer composed of carbon and hydrogen atoms that can be processed using heat.
Tensile and Impact Properties of Natural Fiber Hybrid Composite MaterialsIJMER
This paper is a review on the tensile and impact properties of natural fiber hybrid composites.
Natural fibers are having good mechanical properties, high specific strength, low cost, bio-degradable
and easily can recyclable through thermal methods. In this paper two different hybrid composites were
manufactured by compression molding and properties of tensile and impact results are conducted as per
ASTM standards. In this project three different fibers such as sisal, jute and glass with thermosets epoxy
resin used with weight ratio of fiber to resin as 15:15:70.Results showed that sisal/glass hybrid composite
has more tensile and impact strength while comparing to sisal/jute hybrid composite.
Characterizing the Behavior of Polyurethane GroutYenny Mattei
1. The document investigates the physical properties, compressive behavior, and bonding strength of a hydrophilic polyurethane grout.
2. Tests found that the water-to-grout ratio and volume change during curing influence the grout's pressure-temperature relationships, compressive stress-strain behavior, and tensile bonding strength.
3. The compressive stress-strain behavior of cured grouts was found to be non-linear and inelastic, and affected by the initial water-to-grout ratio and volume change during curing.
The study examined the effect of water temperature during polymerization on the strength of autopolymerizing resin used for provisional restorations. Resin samples were polymerized in air at 23°C or in water at temperatures ranging from 10°C to 80°C, then tested for transverse strength and modulus. Results showed that strength and modulus increased with higher water temperatures, with 60°C and 80°C producing strengths over twice as high as air polymerization. The authors recommend using hot water when fabricating provisional restorations to improve mechanical properties and reduce chair time.
This document analyzes the effects of alkaline and acid solutions on the mechanical properties of glass/epoxy composites. It finds that:
1) Immersion in hydrochloric acid (HCl) and sodium hydroxide (NaOH) solutions decreases the flexural strength and modulus of the composites over time.
2) The alkaline sodium hydroxide solution promotes a higher decrease in flexural properties than the acid hydrochloric solution.
3) Both solutions also decrease the impact strength of the composites with increased exposure time, with the alkaline solution again having a greater effect.
Abrasive jet micro-machining (AJM), in which abrasive parti-cles are accelerated by air and directed toward a target, has beenused to make components for micro-electromechanical (MEMS) and micro-fluidic capillary electrophoresis devices . One ofthe disadvantages of AJM is that the compressed air jet used topropel the erodent particles diverges significantly after the noz-zle exit, increasing the size of the blast zone and the width of thesmallest channel or hole that can be machined without the use of a patterned erosion-resistant mask that defines the micro-featureedges . Abrasive slurry jet micro-machining (ASJM) is similar to AJM except that pressurized water, instead of air, is used to accel-erate the suspended abrasive particles such as garnet or alumina(Al2O3). In both AJM and ASJM, the material removal occurs by ero-sion. However, for the same jet dimension and flow speed, slurryjets have a much lower divergence angle than air jets , allow-ing for the micro-machining of small features without the use ofpatterned masks.
1) The document investigates the effect of carbon fiber content on the mechanical properties of hybrid composite laminates made of woven carbon, glass fibers and epoxy resin.
2) Specimens with different carbon fiber percentages were tested for tensile strength, compression strength, impact strength, and flexural strength.
3) The results showed that increasing the carbon fiber content increased the mechanical properties of the composite laminate in all tests. The specimen with the highest carbon fiber content performed best mechanically.
1. Incremental layering techniques are recommended to reduce polymerization shrinkage stress by decreasing the C-factor at each stage of restoration. This allows for stress relief between increments.
2. Flowable composites with lower elastic moduli have been used as intermediate layers to absorb shrinkage stress from subsequent higher modulus resin composite layers through an "elastic cavity wall" effect. However, flowable composites do not significantly reduce stress.
3. Alternative curing methods like soft-start and pulse-delay curing may slightly reduce shrinkage stress by allowing more time for resin flow before full conversion. However, opportunities for stress relief are still limited and conversion levels may be lower.
Performance of Light-Weight Concrete with Plastic AggregateIJERA Editor
This study is intended to explore the suitability of recycled plastics (high density polyethylene) as coarse aggregate in concrete by conducting various tests like workability by slump test, compressive strength of cube and cylinder, splitting tensile strength test of cylinder, flexural strength of R.C.C as well as P.CC. beams to determine the properties and behaviour in concrete. Effect of replacement of coarse aggregate with various percentages (0% to 40%) of plastic aggregate on behaviour of concrete was experimentally investigated and the optimum replacement of coarse aggregate was found out. The results showed that the addition of plastic aggregate to the concrete mixture improved the properties of the resultant mix.
Effect of Hygrothermal Aging on the Mechanical Properties of Fluorinated and ...Salah Hamim
Hydrophilic nature of epoxy polymers can lead to both reversible and irreversible/permanent changes in epoxy upon moisture absorption. The permanent changes leading to the degradation of mechanical properties due to combined effect of moisture and elevated temperature on EPON 862, Nanomer I.28E, and Somasif MAE clay-epoxy nanocomposites are investigated in this study. The extent of permanent degradation on fracture and flexural properties due to the hygrothermal aging is determined by drying the epoxy and their clay-epoxy nanocomposites after moisture absorption. Significant permanent damage is observed for fracture toughness and flexural modulus, while the extent of permanent damage is less significant for flexural strength. It is also observed that permanent degradation in Somasif MAE clay-epoxy nanocomposites is higher compared to Nanomer I.28E clay-epoxy nanocomposites. Fourier transform infrared (FTIR) spectroscopy revealed that both clays retained their original chemical structure after the absorption-desorption cycle without undergoing significant changes. Scanning electron microscopy (SEM) images of the fracture surfaces provide evidence that Somasif MAE clay particles offered very little resistance to crack propagation in case of redried specimens when compared to Nanomer I.28E counterpart. The reason for the observed higher extent of permanent degradation in Somasif MAE clay-epoxy system has been attributed to the weakening of the filler-matrix interface.
Density measurements Melt flow index test and carbon black test of HDPE Pipespreya772
This document discusses a study to investigate the density, melt flow index (MFI), and carbon black content of high-density polyethylene (HDPE) pipes under different conditions and parameters. The study aims to determine the relationship between these properties and the performance of HDPE pipes. Specifically, it will examine how density, MFI, and carbon black content are affected by temperature, load, molecular weight, and processing conditions. The findings will provide insights into optimizing HDPE pipe design and performance for various applications. Standard methods are described for preparing HDPE pipe specimens and conducting tests to analyze density, MFI, and carbon black content.
Study of Effect of Water Treatment on Flexural Properties of GFRP CompositesIRJET Journal
The document studies the effect of water treatment on flexural properties of glass fiber reinforced polymer (GFRP) composites. Composites were fabricated using glass fiber reinforcement and epoxy resin, and subjected to water immersion for periods of 5 and 10 days. Testing found that water treatment decreased the flexural strength of composites immersed for 5 days but did not further decrease strength for those immersed 10 days. While samples absorbed minimal water, gaining no more than 0.03 grams, water immersion was found to significantly impact flexural strength of the GFRP composites.
This document summarizes a research article that analyzed the surface degradation of polypropylene (PP) and high-density polyethylene (HDPE) composites with 5% and 10% banana fiber loads when immersed in distilled water, ethanol, and sodium chloride solutions for up to 200 days. Samples were weighed over time to measure degradation and absorption in different environments. Surface degradation was also evaluated using scanning electron microscopy. The researchers found that longer immersion times led to greater material degradation regardless of environment.
Investigation of Tribological Behaviour of GF Filled Peek Composite under the...IJERA Editor
Composite materials have successfully substituted the traditional materials in several light weight and high
strength applications. The reasons why composites are selected for such applications are mainly their high
strength-to-weight ratio, high tensile strength at elevated temperatures, high creep resistance and high
toughness. Therefore minimum Wear of component or part used in machinery is very important factor for the
industry. In this paper the tribological behavior of PEEK (Poly-ether-ether-ketone) composites reinforced by
30% short glass fiber and phosphor bronze were comparatively evaluated on Pin on disc machine. The effect of
three parameters such as temperature, load and sliding distance on Wear loss of PEEK composites reinforced by
30% short glass fiber and phosphor bronze were examined. The detailed mathematical model is simulated by
Minitab 17 and simulation results fit experiment data very well
In this investigation, an effective approach based on Taguchi method, analysis of variance (ANOVA),
multivariable linear regression (MVLR), has been developed to determine the optimum conditions leading to
minimum Wear. Experiments were conducted by varying temperature, load and sliding distance using L9
orthogonal array of Taguchi method. The present work aims at optimizing process parameters to achieve
minimum Wear. Experimental results from the orthogonal array were used as the training data for the MVLR
model to map the relationship between process parameters and Wear. The experiment was conducted on
computerized Pin on Disc machine. It was observed that PEEK 30% Glass Fiber Composite Polymer has
excellent wear resistance compare to Phosphor bronze at elevated temperature.
Examples of Mechanical Property EvaluationsJacob Feste
The document summarizes an experiment that measured and compared the viscoelastic properties of four polymers: low density polyethylene (LDPE), high density polyethylene (HDPE), Neoprene, and Red Silicone. Creep and hysteresis tests were performed on LDPE and Neoprene samples, while stress relaxation tests were conducted on HDPE and Red Silicone samples using an Instron machine. The results showed that LDPE lost significantly more average energy (38,653 N/m2) than Neoprene (3,261.5 N/m2) in the hysteresis tests, and HDPE exhibited a larger change in stress over time compared to Red Silicone in the stress relaxation tests.
This document summarizes research into improving the impact strength and heat deflection temperature of poly(lactic acid) (PLA) biocomposites. The researchers created biocomposites from a ternary blend of PLA, poly(ether-b-amide), and ethylene-methyl acrylate-glycidyl methacrylate with 10% miscanthus fibers. Adding 1% of the nucleating agent Lak-301 and molding at 110°C resulted in biocomposites with 42% crystallinity, a 4-fold increase in impact strength over neat PLA, and an increased heat deflection temperature from 55°C to 85°C. The presence of the nucleating agent significantly
Ekeeda Provides Online Engineering Subjects Video Lectures and Tutorials of Mumbai University (MU) Courses. Visit us: https://ekeeda.com/streamdetails/University/Mumbai-University
Ekeeda Provides Online Engineering Subjects Video Lectures and Tutorials of Mumbai University (MU) Courses. Visit us: https://ekeeda.com/streamdetails/University/Mumbai-University
Testing of Already Existing and Developing New Compaction Equations during C...IJMER
Powder Metallurgy (P/M) processing of materials to produce conventional P/M parts
involve the compaction of the pre-determined mass of individual elemental, mixed elemental metal
powders or alloy powders and or composite powders into green compacts and sintering them under
reducing atmosphere and or under other protective coatings, thus, after sintering producing
products after mild machining operations. Therefore, compaction represents one of the most
important stages in the production of engineering components using the P/M route. However, the
physical properties such as density and the stress distribution in the green compacts are determined
not only by the properties of the constituents of the powder or the powder blend, but, also by the
pressing modes and schedules. Thus, the present investigation pertains to generate experimental
data on the compaction behaviour of Fe-1.05% graphitesystems with two different iron particle size
ranges and two different powder masses in order to highlight the various aspects of compaction and
also testing out the already existing compaction equations and search for the new ones. Powder
blends of two different iron powder particle size ranges, namely, -106+53µm and -150+106µm
respectively were blended with the required amount of graphite powder of 3 – 5 µm sizes for a
period of 32 hours. Compaction studies have been carried out for two different amounts of both
powder blends. The two amounts taken were 65g and 85g respectively. However, the main attempt
was made to record the load and the corresponding heights and the top punch displacements for
every two tons (0.02MN) of load which was applied in the steps of 0.02MN. Various equations for
compaction were attempted empirically and the already existing ones were also tested. Critical
analysis of the experimental data and the calculated parameters have resulted into several
compaction equations which were arrived at empirically. The regression coefficient ‘R2
’ in each
case where compactions equations were empirically obtained was in very much close proximity to
unity. However, it has been also confirmed that the data of the present investigation were well
taken up by the earlier compactions equations, thus, validating them comprehensively.
Similar to Mechanical Response of Ageing and Annealing on Injection Molded High Density Polyethylene_Revised (20)
Testing of Already Existing and Developing New Compaction Equations during C...
Mechanical Response of Ageing and Annealing on Injection Molded High Density Polyethylene_Revised
1. MECHANICAL RESPONSE OF AGEING AND ANNEALING ON INJECTION
MOLDED HIGH DENSITY POLYETHYLENE
Reaj U Ahmed, Niagara Bottling, LLC, Ontario, CA
Jay C Hanan, Oklahoma State University, Tulsa, OK
Abstract
Short term stress relaxation tests were performed to
observe mechanical effects of ageing and annealing on
injection molded High Density Polyethylene (HDPE).
The investigation revealed no definite relationship
between ageing time and relaxed stress. Two different
annealing parameters were used to investigate the effect
of annealing on injection molded samples. Samples
annealed for longer time showed more consistency and
higher relaxation modulus than the samples annealed for
shorter time and the control samples. The effect of ageing
on annealed samples was also studied in this work.
Introduction
High Density Polyethylene (HDPE) is a thermoplastic
and represents the largest portion of PE produced. Due to
its higher density and crystallinity, HDPE is much stiffer
and stronger than LDPE. HDPE is efficient for injection
molding, blow molding, and extruded items, which makes
it a preferred material in manufacturing products like
personal care, household industrial containers, and bottles.
HDPE is universally recognized as a ‘safer’ plastic and
meets the U. S. Food and Drug Administration (FDA)
requirements for direct food contact applications. HDPE
is more often used in the container of liquids that are
stored at atmospheric pressure [1,2,3]. After production,
these containers are stored in plants or distribution center
warehouses for extended periods and so time dependent
properties like “ageing” can become significant.
Moreover, in production processes like injection molding,
parts are subjected to rapid cooling which introduces
thermal residual stress. These thermal stresses are
expected to relax with increasing ageing time [4].
Removal of waste is a driving force in industry, which
results in removal of unnecessary materials from existing
designs and adds value to alternative approaches for
strengthening materials. Among different approaches,
annealing is one of the popular approaches to modify
polymers as an annealing unit can be incorporated easily
to existing manufacturing processes. Annealing is
assumed to improve the final properties of a polymer via
reduction or elimination of solidification defects, residual
stress, and strain. Motivated by all these reasons, ageing
and annealing in HDPE were studied here with an
emphasis on mechanical performance. Most research
work on HDPE have been done on samples fabricated by
compression molding in lab scale equipment. As the
properties of polymers are highly process dependent, the
behavior of HDPE parts manufactured by different
laboratory processes may be incomplete compared to
industry practice. In this work, HDPE samples were
collected from one piece HDPE closures produced by an
industry scale injection molding machine. Stress
relaxation was set as criteria to determine the effect of
annealing and ageing. Two different annealing
parameters were used to investigate the effect of
annealing on two sets of samples. Samples were air
cooled and the effect of ageing on annealed samples was
also studied.
Ageing of polymers has been studied by several
researchers. Iacopi and White [5] showed the effect of
ageing on injection molded polystyrene bars and found
higher density of the bar with more ageing time. Struik
[6] studied the physical ageing of amorphous materials
and examined creep behavior of materials in different
states of ageing. Struik’s data and analysis were in good
agreement with the engineering properties. Several
researchers have concentrated on the ageing of
semicrystalline polymers. Besides the contribution of the
amorphous phase of semi-crystalline polymers, secondary
crystallinity [7,8] and molecular rearrangement can be a
potential source of ageing in semi-crystalline polymers.
This has been observed and analyzed by White [9],
Siegmann and Kenig [10]. McCrum [11] considered the
effect of crystallinity in his investigation, but Struik [12]
claimed that secondary crystallization is not strong
enough to explain his ageing observation with
polypropylene. In some of his other papers [13, 14, 15,
16] Struik concentrated on the behavior of the amorphous
phase to interpret the physical ageing of semi-crystalline
polymers. He explained the effect of the presence of the
crystal unit in the amorphous phase on molecular
relaxation [17]. A model describing the effect of physical
ageing on the stress relaxation behavior of HDPE at room
temperature was developed by Kubat et al [18]. The
model was based on the separation of the amorphous
phase into two parts as suggested by Struik [21]. Kubat et
al [19] studied the viscoelastic properties of clay filled
and unfilled HDPE after different ageing times on
samples annealed for 8 hours at 120o
C. They used
compression molded samples and found ageing time had a
pronounced influence on the viscoelastic properties of
HDPE. They found the internal stress (evaluated from
stress relaxation data) was increased markedly when the
ageing period was extended. In another paper Kubat et al.
2. [20] studied the effect of ageing on internal stress of
HDPE filled with glass spheres. They found the internal
stress increased with the degree of interaction of the
filler/matrix interface and the ageing time. They found
the surface treatment of the filler had a significant effect
on creep behavior at high applied stress levels and on
ageing behavior of the composites. Welander et al. [21]
studied the influence of high stress on the ageing behavior
of HDPE. They found high applied stress and strain erase
the effect of ageing time on the creep and stress relaxation
behavior of HDPE. They observed change due to ageing
was not same at low and high applied stresses. All of the
previous work regarding ageing of HDPE were
concentrated on samples aged for longer times. The
change of properties at shorter time intervals after
solidification was not studied fully, which with industry’s
trend toward just in time production is important for
understanding the compatibility of different final
products. This motivated us to investigate the change of
HDPE properties at times relevant for many modern
production processes.
Annealing of polyethylene involves reheating of the
polymers for a period of time after they have been
processed. Polymeric molecules solidify in a stressed
position during the manufacturing process such as
injection molding or extrusion. A sudden drop of
temperature during molding freezes the molecules at non-
equilibrium positions influenced by the melt inside the
mold. Annealing relaxes these frozen or residual stresses.
Crystallinity also changes by annealing. Crystals can
grow over time until reaching equilibrium at the annealing
temperature. Relaxation of the residual or frozen stresses
can improve tensile strength, impact strength, and slow
crack growth characteristics [22]. While rapid cooling
suppresses the formation of crystals and gives tough, clear
products, annealing or slow cooling provides relatively
brittle and hazy products [23]. Annealing at high pressure
also leads to the formation of large crystallites with
relaxation of stressed chains and, hence, increases
molecular mobility in amorphous regions [24].
Tiemprateeba et al. [25] studied the effect of annealing on
neat and CaCO3 filled HDPE, and reported that melting
temperature, crystallinity, modulus, and tensile strength
increase with increasing annealing temperature. They
observed the increase of these properties stabilizes at an
annealing temperature of 135-140o
C, and further
increasing of temperature did not significantly alter the
properties. The modulus and yield stress of the samples
increased, at annealing temperatures (Ta) greater than
120o
C. In their tests, yield strain did not show relevance
with annealing temperature. They found for the filled
composites, the degree of crystallinity, and melting
temperature did not depend on the percentage of filler
materials, but depended on annealing temperatures
(increased as Ta increases). Annealing showed a much
higher modulus and tensile strength for the filled
composites. Suwanprateeb [26] used vickers
microhardness and thermal analysis (DSC) for studying
the annealing condition of HDPE and found increasing
annealing temperature increased properties like
crystallinity, melting temperature, tensile modulus, tensile
yield strength, and microhardness. They found
microhardness can be employed as an alternative to
tensile testing in studying the annealing conditions for
HDPE. Tsuruta et al. [27] studied the annealing
characteristics of HDPE fibers extruded at different
constant extrusion draw ratios. Annealing can improve
the modulus more than radiation effects. Suwanprateeb et
al. [28] showed that thermal ageing (annealing) can
improve the modulus for both neat HDPE and
hydroxyapatite (HA)-HDPE composites, while gamma
radiation did not show such significant increases in
modulus values. They observed around a 4% increases in
crystallinity due to annealing of the samples. All these
studies regarding annealing motivates an investigation
into the effect of annealing on stress relaxation of
injection molded samples.
Experimental
Materials and Samples
Samples for this research work were cut from
injection molded closures. High Density Polyethylene
(HDPE) with a melt flow index 11.0 g/10 min and a
density of 0.951 g/cc were used as resin. A Husky
Hylectric 300 was used for injection molding of the
closures. Resin was processed at 201o
C barrel
temperature and 225o
C mold temperature with 0.7 sec
cooling time. Closures were collected immediately after
production. Uniform rectangular samples with
dimensions of 15mm×5 mm were cut from the closures
for observation by DMA.
Ageing
For investigation of the ageing effects, a group of
closures were collected just after injection molding and
short term stress relaxation tests were performed after
increasing lengths of time of 15 to 30 min each, as
indicated in the results section.
Annealing
For annealing, two different annealing parameters
were set for two groups of samples. The first group was
annealed at 125o
C for 30 minutes and the second group
was annealed at 125o
C for 1 hour in an oven. Both groups
of samples were air cooled after annealing.
3. Stress Relaxation
ASTM D 4065 was followed and a tension film
clamp was used in the DMA measurements. Stress
relaxation tests were conducted at 0.9% static strain with
0.001 N static force for 15 to 20 minutes. All of the tests
were performed at 30o
C with a 1 minute soak time.
Results and Discussion
Ageing
The ageing effect on HDPE was investigated for both
non-annealed and annealed samples.
Non-annealed samples
Figure 1 and Figure 2 shows stress relaxation curves
for non-annealed samples. A wide range of relaxed stress
is observed in Figure 2. No definite relationship was
found between the ageing time and the relaxed stress.
Figure 3 shows the stress at different times of stress
relaxation tests for the aged samples. The reason for
getting a wide range of stress relaxation curves can be
explained by the concept of molecular equilibrium. As
samples were collecected from injection molded caps,
some residual stress could be trapped during rapid cooling
at demoulding and molecules of the polymers were not at
equilibrium. As a result, a wide variety of stress
relaxation behavior was observed.
31
88
159
230
315
492
562
1972
0
0.5
1
1.5
2
2.5
3
3.5
1 1 1 1 1 2 2 2 3 4 5 7 10 14 19
Stress(MPa)
Figure 1. 3D plot of relaxed stress in non-annealed sample
having increased age.
0
0.5
1
1.5
2
2.5
3
3.5
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Stress(MPa)
Relaxation Time (min)
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88
119
159
194
230
282
315
463
492
522
562
1944
1972
Age (minute)
Figure 2. 2D plot of relaxed stress in non-annealed sample
having increased age
0
0.5
1
1.5
2
2.5
3
3.5
4
0 500 1000 1500 2000
Stress(MPa)
Ageing Time (min)
10 sec
2 min
4 min
9 min
15 min
Figure 3. Stress vs. ageing time at different test time
(Non-annealed sample).
Annealed Samples
Annealed for 30 minutes
Figure 4 and Figure 5 show the stress relaxation curves
for 30 minute annealed samples. Figure 6 depicts the
relaxed stress as a function of ageing time at different test
time of stress relaxation tests.
57
115
307
358
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 3 3 3 4 5 5 6 7 8 10 12 14 16 19 21
Stress(MPa)
Figure 4. 3D plot of relaxed stress in annealed (30min)
sample having increased age.
4. 0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
0 2 4 6 8 10 12 14 16 18 20 22 24
Stress(MPa)
RelaxationTime (min)
57
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115
166
307
331
358
Age (minute)
Figure 5. 2D plot of relaxed stress in annealed (30 min)
samples having increased age.
0
1
2
3
4
5
0 100 200 300 400
Stress(MPa)
Ageing Time (min)
10 sec
1 min
2 min
5 min
9 min
15 min
Figure 6. Stress vs. ageing time at different test time
(symbol). Samples were annealed at 1250
C for 30
minutes.
Annealed for 1 hour
Figure 7 and Figure 8 show stress relaxation for
different age samples with 1 hour of annealing. Figure 9
shows the effect of ageing time on relaxed stresses at
different test times. Unlike non-annealed and 30 minute
annealed samples, the stress relaxation curves for 1 hour
annealed samples are not widely distributed.
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94
225
332
0
0.5
1
1.5
2
2.5
3
3.5
4
1 1 1 1 1 2 2 2 3 4 5 7 10 14
Stress(MPa)
Figure 7. 3D plot of relaxed stress in annealed (1 hour)
sample having increased age.
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
Stress(MPa)
RelaxationTime (min)
39
63
94
121
225
252
332
Age (minute)
Figure 8. 2D plot of relaxed stress in annealed (1 hour)
sample having increased age.
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
0 100 200 300 400
Stress(MPa)
Ageing Time (min)
10 sec
2min
5 min
9 min
15 min
Figure 9. Stress vs. ageing time at different test time.
Samples were annealed at 125o
C for 1 hour.
Annealing accelerates ageing. These results suggest
annealing at 1 hour provided sufficient time and energy to
relax more residual stress letting the molecules of the
polymer settled in more equilibrium states than the non-
annealed and 30 minute annealed samples. However,
ageing after 1 hour annealing did not show a significant
influence on the magnitude of stress relaxation. On the
other hand, the samples which were annealed for 30
minutes had less time and energy to reach the equilibrium
then the samples which were annealed for 1 hour. As a
result, they were further from equilibrium and still some
residual stress could exist. So additional ageing after
annealing showed effects on the stress relaxation tests of
these samples. The samples which were not annealed at
all, showed a much wider range of stress relaxation curves
as their polymer chains were not in equilibrium. Figure
10 shows the standard deviation of stress as a function of
annealing time after 15 min of stress relaxation tests. The
standard deviation of average stress was found 32% less
for 1 hour annealed HDPE than the non-annealed HDPE.
5. 0
0.05
0.1
0.15
0.2
0.25
1
StandardDeviation(MPa)
Annealing time (hour)
0 0.5 1
Figure 10. Standard deviation of stress among different
samples as a function of annealing time after 15 min of
stress relaxation.
Annealing
Figure 11 shows the stress relaxation curves for
annealed and non-annealed samples. From the figure, the
relaxation modulus for 1 hour annealed HDPE is
significantly higher than that of non-annealed, and 30
minute annealed HDPE. Figure 12 depicts the
comparison of average stresses at different time of stress
relaxation tests for annealed and non-annealed HDPE.
HDPE annealed for 1 hour showed higher stress than the
other two shorter times throughout the entire stress
relaxation test. After 15 minutes of stress relaxation,
HDPE annealed for 1 hour held 24% higher average stress
than the non-annealed HDPE. At the beginning of the
relaxation tests, 30 minute annealed samples showed
slightly higher values of stresses than the non-annealed
samples. But as tests went on, stresses for 30 minute
samples were found lower than non-annealed samples
(Figure 12).
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Stress(MPa)
RelaxationTime (min)
1 H_A 94 min old
30 m A 358 min old
Non-Annealed 119 min old
Annealed for 1 hour
Annealed for 30 minutes
Figure 11. Plot of stress relaxation curves for annealed
and non-annealed HDPE.
0
1
2
3
4
1
Stress(MPa)
0
1
2
3
4
1
Stress(MPa)
b)
0
1
2
3
4
1
Stress(MPa)
c)
1 0.5 0
0
1
2
3
4
1
Stress(MPa)
d)
1 0.5 0
a)
AnnealingTime (hours) Annealing Time (hours)
Figure 12. Comparison of stresses for non-annealed and
annealed samples at 4 test times of stress relaxation
tests; a) after 10 seconds, b) after 2 minutes, c) after 9
minutes, d) after 15 minutes.
From Figure 11 and Figure 12 it is evident that 1 hour
annealing increases the relaxation modulus of neat HDPE.
The evidence here suggests that after 1 hour annealing,
residual stresses were generally relaxed as the polymer
chains had enough time to reach equilibrium. As
annealing can also increase the crystallinity of HDPE
[27], this could be another reason for the increase in
relaxation modulus.
For high speed manufacturing this one factor may be
the most important one uncovered in the present work.
Annealing reduces variation at least through minimizing
residual stresses. Reduced variation is important in
manufacturing. Less variation means fewer jams or other
inconsistencies during automated handling and application
of parts. Along with more consistent leak pressures,
increased stress relaxation should lead to increased seal
strength for HDPE used as closures.
6. Conclusions
The mechanical effect of short term ageing and
annealing was investigated on injection molded HDPE.
Short term changes in polymer mechanical properties
were speculated from industry experience but have now
been experimentally confirmed. Stress relaxation tests
were used to measure relevant changes in mechanical
properties from ageing and annealing. While, no definite
relationship was found between the ageing time and the
relaxed stress. Samples were also annealed at 125o
C for
30 minutes and 1 hour. Annealing for 1 hour showed
more consistency in stress relaxation than shorter times.
Consistency is critical for high speed manufacturing. In
addition to more consistency, after 15 minutes of stress
relaxation, HDPE annealed for 1 hour held a 24% higher
average stress than non-annealed HDPE. While
crystallization can also play a role, residual stress may be
the most significant source of change for these short
times. Future work is needed to measure the role of
crystallization and also to link these shorter time studies
with longer time scales.
Acknowledgement
The authors would like to acknowledge Dr. Elizabeth
J. Orwin, Harvey Mudd College for use of the DMA
Q800 instrument. The authors also acknowledge Niagara
Bottling, LLC for sponsoring the project and providing
the samples. This work is part of an industry sponsored
research program at Oklahoma State University’s
Helmerich Research Center.
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