Flexural modulus of the unidirectional and random composites made from biodegradable resin and bamboo and kenaf fibres

Bio-based polymer composites made from kenaf, bamboo and biodegradable resin, which was a corn starch base were fabricated with press forming. The relationship between fibre Young’s modulus and flexural modulus in composites was investigated. The Young’s modulus of each fibre was measured to predict the flexural modulus in composites. The flexural modulus in composites was predicted by Cox model, which incorporates the effect of the fibre compression. The flexural modulus increased with increasing the fibre content. In the case of kenaf, the flexural modulus in the experimental was in good agreement with the experimental. While in the case of bamboo, the difference between experimental and calculation was large. This is because Young’s modulus in bamboo was estimated considerably lower than the actual modulus due to partial breakage of bamboo during single fibre tensile test. The flexural modulus in unidirectional fibre composite made a good agreement with the predicted. However, the flexural modulus in cross ply composite was considerably lower than the predicted. This is because less fibres movement during hot pressing resulted in the resin segregation and the movement made the fibres less wetting with resin.