Abstract
In this study, bast fibers of kenaf (Hibiscus cannabinus L.), in the form of randomly dispersed short-fiber reinforcement, were loaded into poly(lactic acid) (PLA) or simply polylactide. Twin-bladed melt mixing followed by hot-pressing was chosen as the present composite molding with fiber weight fractions varied from 0wt% (i.e. neat PLA) to 20wt% by 5wt% increment. From the optical microscopic surface images, kenaf fibers were found to evenly be dispersed in the present composites with random fiber orientations in the two-dimensional flat-wise directions. Tensile strength and strain at break of the composites were found to decrease as compared to those of neat PLA. On the other hand, the tensile moduli both at initial and at several stress levels up to the final breakage were found to be improved via kenaf fiber loading. Two-parameter Weibull plots in terms of tensile strength and SEM fractography of the fractured surfaces were also examined and complicated and multiple sources for the fracture initiation and propagation in the present composites were implied. Finally, flexural properties, Charpy impact toughness, plain strain fracture toughness and S-N curves for the present composites were also shown and then discussed to sustain some benefits of the kenaf fiber loading.
