Effect of Heat Treatment on Properties of Kenaf Fiber Mat/Unsaturated Polyester Composite Produced by Resin Transfer Molding

摘要

This study investigated the effect of heating time during heat treatment on mechanical and physical properties of the kenaf fiber and its composites. Kenaf bast fibers were modified by heat treatmentat 140°C for 2.5, 5, 7.5, 10 and 12.5 hours. Composites were fabricated by resin transfer molding process with unsaturated polyester as matrix and needle-punched kenaf fiber mat as reinforcement. The fibers were characterized by Fourier Transform-Infra Red (FT-IR) and X-Ray Diffraction (XRD). FT-IR results showed the changes in intensity of hemicelluloce wavelength (1736 cm~(-1)). Besides XRD observation also confirmed the increase of cellulose content in kenaf that described to the increase of crystallinity index of kenaf fiber with heat treatment. The single fiber strength investigation stated that the highest strength and modulus was obtained by kenaf fiber heated for 10 hours in drying oven. SEM observation showed the decreasing numbers of impurities on the fibers surface with fiber treatment compared to untreated kenaf fibers. The flexural properties of composites showed a similar trend to fiber strength, however the fracture toughness has showed contrary results.