Polylactic acid (PLA: TE-2000C) with a density of 1.25 g/cm3
was obtained from Unitika plastics
division. The natural fiber consisting of bamboo fiber (BF), vetiver grass fiber (VF) and coconut fiber
(CCF) (all materials obtained from Thailand without any pre-sizing treatment) were selected as the
reinforcement for PLA. The composition and characteristic of selected natural fibers were listed in Table
1. Flexible epoxy resin (Epoxidized polybutadiene, EPOLEAD PB 3600, Daicel chemical Co. Ltd., Japan)
was used as surface treatment for the natural fibers.