Effect of Molding Condition on the Mechanical Properties of Bamboo-Rayon Continuous Fiber/Poly(Lactic Acid) Composites

Natural fiber reinforced composite materials attract much attention in relation to the present global environmental problem. Continuous natural fiber reinforced thermoplastic composites have superior mechanical properties and have great potential as structural materials. However, it is difficult to impregnate reinforcement fibers with thermoplastics because of the high viscosity of molten plastics. In this study, continuous natural fiber reinforced thermoplastic composites were molded using intermediate materials fabricated through the micro-braiding technique. Bamboo-rayon fiber and poly(lactic acid) (PLA) fibers were used as reinforcement and matrix, respectively. Composite plates were fabricated by hot press molding under various molding conditions, including molding temperature, pressure and time. Tensile and shear tests were conducted to evaluate the effect of molding condition on mechanical properties of the composites. Tensile and shear strength increased with increasing molding temperature, whereas they are little affected by molding pressure and time. It was clarified that a molding temperature of 190°C, molding pressure of 1 MPa and molding time of 4 min are optimum molding conditions that lead to securing the best tensile strength ratio.