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Ultrahigh molecular weight polyethylene (UHMWPE) modified polyester-cotton composites were developed and studied for friction and sliding wear behaviour at different applied loads and UHMWPE concentrations. Sliding wear tests were conducted by using pin-on-disc apparatus. Composites in the form of the pin were tested against EN-24 steel disc. The specific wear rate of polyester reduced on reinforcement of cotton and on addition of UHMWPE. The coefficient of friction of polyester resin increased on cotton reinforcement and reduced significantly on addition of UHMWPE in cotton polyester composite. The composites exhibited reductions in specific wear rate against the normal load in the specimens those containing 7.41 or higher volume percent of UHMWPE. The significant reduction in wear rate of UHMWPE modified polyester-cotton composite has been discussed with the help of SEM observations of worn surfaces and coefficient of friction. The addition of 14.19 vol.% UHMWPE in polyester resin brought down the value of l to nearly half to that of polyester resin and 1/3rd of cotton polyester composite.

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A graded distribution of graphite particles in epoxy resin matrix was obtained using a centrifugation technique. By varying the centrifugation time the graded profile could be effectively controlled. Scanning electron microscopy and optical microscopy revealed the graded dispersion of graphite particles in the epoxy matrix, which is sensitive to centrifugation time. Electrical or wear properties can accurately estimate the property profile of graded material. The abrasive wear test also provided a quick estimation of the extent of gradient formed in the sample. The increased centrifugation time increased the compaction of graphite particles in the graphite-rich phase of graded material that could be correlated with the increased capacitance of the sample.

A novel hybrid composition of sisal fibrils and kenaf fibers has been introduced first time as reinforcement in composite preparation for the environmental friendly high strength electrical insulation applications. Hybrid reinforcement was increased from 10 to 40 wt% in unsaturated polyester resin. The sisal fibril used in this study was extracted from sisal fiber. Alkali treatment was employed and FTIR analysis was done to study its effect on sisal fibrils and kenaf fibers. A positive hybridization effect was observed for the composites. Hybrid composite showed 24 and 18% increase in tensile strength, 30 and 36.4% increase in flexural strength, and 196.3 and 196% increase in impact strength as compared to the composites having same loading of 40 wt% with sisal fibrils and kenaf fibers, respectively. Scanning electron microscopy of the fractured mechanical testing samples was carried out to understand the nature of fibril/fiber/matrix interface. Electrical characterization showed high electrical insulation capability of the hybrid composites. Thermal stability of hybrid composites was also found higher than sisal fibrils and kenaf fibers reinforced composites. A comparative study of properties of sisal fibril/kenaf fiber reinforced hybrid polyester composites with various single and hybrid fiber composites is done. It has been concluded that the developed novel hybrid composite has the potential to replace various existing natural and synthetic fiber composites. POLYM. COMPOS., 40:664–676, 2019. © 2017 Society of Plastics Engineers