In this study, the impact strengths of E-glass, coir, oil palm as well as E-glass/coir and E-glass/oil palm hybrid polyester composites were studied. All types of composites were reinforced with fiber volume fractions of 30%, 40%, and 50% and fiber lengths 3, 7, and 10 mm. Composite laminates reinforced with longitudinal and transverse coir fiber mats were also studied. The number of fiber mats varied from 1, 2, 3, and 4 layers for non-spaced fiber mats and 2, 3, and 4 layers for 1.5 mm spaced fiber mats. Besides, coir—polyester composite with addition of sand filler was studied as well, with 40%, 50%, and 60% of volume fractions and fiber lengths of 3, 7, and 10 mm. Results show that impact strength improves with fiber content and fiber length. In addition, longitudinal fiber mats always exhibit better impact toughness compared to transverse fiber mats. Impact strength is improved with the number of fiber layers but worsened by the fiber spacing. As for coir/polyester concrete, low fiber content and fiber length improve the impact strength. The fractured surfaces were inspected under scanning electron microscope to investigate the fracture mechanisms in each type of composites.
Polymer nanocomposites with enhanced performances are becoming a trend in the current research field, overcoming the limitations of bulk polymer and meeting the demands of market and society in tribological applications. Polytetrafluoroethylene, poly(ether ether ketone) and ultrahigh molecular weight polyethylene are the most popular polymers in recent research on tribology. Current work comprehensively reviews recent advancements of polymer nanocomposites in tribology. The influence of different types of nanofiller, such as carbon-based nanofiller, silicon-based nanofiller, metal oxide nanofiller and hybrid nanofiller, on the tribological performance of thermoplastic and thermoset nanocomposites is discussed. Since the tribological properties of polymer nanocomposites are not intrinsic but are dependent on sliding conditions, direct comparison between different types of nanofiller or the same nanofiller of different morphologies and structures is not feasible. Friction and wear rate are normalized to indicate relative improvement by different fillers. Emphasis is given to the effect of nanofiller content and surface modification of nanofillers on friction, wear resistance, wear mechanism and transfer film formation of its nanocomposites. Limitations from the previous works are addressed and future research on tribology of polymer nanocomposites is proposed.
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