Residual Tensile Stress of Kenaf Polyester and Kenaf Hybrid under Post Impact and Open Hole Tensile

Natural fibres have emerged as the potential reinforcement material for composites and have thus gained an attraction by many researchers. This is mainly due to their applicable benefits as they are light weight and offer low cost compared to synthetic fibre composites. Kenaf fibres recently have been a substitute material in many weight-critical applications in areas such as aerospace, automotive and other high demanding industrial sectors. In this study, natural fibre kenaf composites and kenaf/fibreglass hybrid composites were fabricated by a combination of hand lay-up and cold-press methods. The post impact tensile and open hole tensile of long kenaf fibre composites with and without the addition of fibreglass were further studied. The fracture behaviour verified qualitatively via scanning electron microscopy. A significant improvement in tensile strength and modulus were indicated by the introduction of long kenaf/woven fibreglass hybrid composite. Investigation on the tensile and low velocity impact of kenaf composites and kenaf/fibreglass reinforced polyester resin composites revealed that the composites were seriously impaired when a low energy impact was applied. The tensile strength of open hole long kenaf composites was more notch sensitive than long kenaf/woven glass hybrid composite. Although the hybrid composite was stronger than pure kenaf composites, the damage progression mechanisms in the two materials were very similar. In the above case the polymer matrix failed initially. It is followed by fibre matrix debonding and finally ending in fibre ruptures or pull-outs.