Doping of nanoparticles into the polymer can tailor its mechanical properties. Mixing of the nano... more Doping of nanoparticles into the polymer can tailor its mechanical properties. Mixing of the nanoparticles with the polymer is the most critical issue there. Better mixing between these two can provide higher strength and stiffness whereas poor mixing is seen to decrease ...
Tensile and mode-I fracture behavior of cross-linked polyvinyl chloride (PVC) and rigid polyureth... more Tensile and mode-I fracture behavior of cross-linked polyvinyl chloride (PVC) and rigid polyurethane (PUR) foams are examined. Tension tests are performed using prismatic bar specimens and mode-I fracture tests are performed using single edge notched bend (SENB) specimens under three-point bending. Test specimens are prepared from PVC foams with three densities and two different levels of cross-linking, and PUR foam with one density. Tension and quasi-static fracture tests are performed using a Zwick/Rowell test machine. Dynamic fracture tests are performed using a DYNATUP model 8210 instrumented drop-tower test set up at three different impact energy levels. Various parameters such as specimen size, loading rate, foam density, cross-linking, crack length, cell orientation (flow and rise-direction) and solid polymer material are studied. It is found that foam density and solid polymer material have a significant effect on tensile strength, modulus, and fracture toughness of polymer foams. Level of polymer cross-linking is also found to have a significant effect on fracture toughness. The presence of cracks in the rise-and flow direction as well as loading rate has minimal effect. Dynamic fracture behavior is found to be different as compared to quasi-static fracture behavior. Dynamic fracture toughness (K d ) increases with impact energy. Examination of fracture surfaces reveals that the fracture occurs in fairly brittle manner for all foam materials.
In this paper two types of polymeric foams, namely, cross-linked poly-vinyl chloride (PVC) and po... more In this paper two types of polymeric foams, namely, cross-linked poly-vinyl chloride (PVC) and polyurethane (PUR) were examined under compression loading at different strain rates. Quasi-static compression tests were performed using a servo-hydraulic material testing system (MTS) at strain rate of 0.001, 0.01, and 0.1 s −1 . Higher strain rate compression tests were performed using a split Hopkinson pressure bar (SHPB) apparatus with polycarbonate bars at strain rate ranging from 130 to 1750 s −1 . PVC foams with three densities and two microstructures, and PUR foams with two densities were considered. All foam specimens were tested in the thickness (rise) direction and the stress-strain responses at different strain rate were established to determine the peak stress and energy absorption. Both peak stress and energy absorption were found to be dependent on foam density, foam microstructure, and strain rate. A power law relationship between the peak stress and foam density revealed that the constants were different at different strain rate. Microstructural examinations of the failed specimens showed that PUR foams disintegrated completely around 1600 s −1 whereas PVC foams densified completely like a solid material.
Nanotechnology is presently seen as one of the most promising approaches in the field of material... more Nanotechnology is presently seen as one of the most promising approaches in the field of materials science towards the development of advanced materials for future engineering applications. Recent and ongoing researches on polymer/inorganic nanocomposite have ...
Doping of nanoparticles into the polymer can tailor its mechanical properties. Mixing of the nano... more Doping of nanoparticles into the polymer can tailor its mechanical properties. Mixing of the nanoparticles with the polymer is the most critical issue there. Better mixing between these two can provide higher strength and stiffness whereas poor mixing is seen to decrease ...
Tensile and mode-I fracture behavior of cross-linked polyvinyl chloride (PVC) and rigid polyureth... more Tensile and mode-I fracture behavior of cross-linked polyvinyl chloride (PVC) and rigid polyurethane (PUR) foams are examined. Tension tests are performed using prismatic bar specimens and mode-I fracture tests are performed using single edge notched bend (SENB) specimens under three-point bending. Test specimens are prepared from PVC foams with three densities and two different levels of cross-linking, and PUR foam with one density. Tension and quasi-static fracture tests are performed using a Zwick/Rowell test machine. Dynamic fracture tests are performed using a DYNATUP model 8210 instrumented drop-tower test set up at three different impact energy levels. Various parameters such as specimen size, loading rate, foam density, cross-linking, crack length, cell orientation (flow and rise-direction) and solid polymer material are studied. It is found that foam density and solid polymer material have a significant effect on tensile strength, modulus, and fracture toughness of polymer foams. Level of polymer cross-linking is also found to have a significant effect on fracture toughness. The presence of cracks in the rise-and flow direction as well as loading rate has minimal effect. Dynamic fracture behavior is found to be different as compared to quasi-static fracture behavior. Dynamic fracture toughness (K d ) increases with impact energy. Examination of fracture surfaces reveals that the fracture occurs in fairly brittle manner for all foam materials.
In this paper two types of polymeric foams, namely, cross-linked poly-vinyl chloride (PVC) and po... more In this paper two types of polymeric foams, namely, cross-linked poly-vinyl chloride (PVC) and polyurethane (PUR) were examined under compression loading at different strain rates. Quasi-static compression tests were performed using a servo-hydraulic material testing system (MTS) at strain rate of 0.001, 0.01, and 0.1 s −1 . Higher strain rate compression tests were performed using a split Hopkinson pressure bar (SHPB) apparatus with polycarbonate bars at strain rate ranging from 130 to 1750 s −1 . PVC foams with three densities and two microstructures, and PUR foams with two densities were considered. All foam specimens were tested in the thickness (rise) direction and the stress-strain responses at different strain rate were established to determine the peak stress and energy absorption. Both peak stress and energy absorption were found to be dependent on foam density, foam microstructure, and strain rate. A power law relationship between the peak stress and foam density revealed that the constants were different at different strain rate. Microstructural examinations of the failed specimens showed that PUR foams disintegrated completely around 1600 s −1 whereas PVC foams densified completely like a solid material.
Nanotechnology is presently seen as one of the most promising approaches in the field of material... more Nanotechnology is presently seen as one of the most promising approaches in the field of materials science towards the development of advanced materials for future engineering applications. Recent and ongoing researches on polymer/inorganic nanocomposite have ...
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