Abstract
Continuous natural fiber reinforced thermoplastic composites have superior mechanical property and have often been used as structural material. However, during the composite fabrication process, it is difficult to impregnate the thermoplastic resin into the reinforcement fibers because of the high melt viscosity. In our previous studies, an intermediate material was produced to promote resin impregnation during molding. Continuous fiber reinforced thermoplastic composites can be obtained by aligning the intermediate materials made from resin fibers wrapped around reinforcing natural fibers through the braiding technique. This intermediate material is called the “Micro-braided-yarn.” In this investigation, 100% naturally-derived micro-braided-yarns were fabricated by using poly-(lactic acid) (PLA) as the resin fiber and jute spun yarn as the reinforcement. Composite plates were fabricated by hot press molding under various molding conditions. Observation of the impregnation state and evaluation of mechanical properties were performed. The relationship between the fabrication conditions and the mechanical properties of jute spun yarn/PLA composite was clarified. The composite strength was affected by the resin impregnation into the fiber bundle, extent of thermal deterioration of jute fibers, and dispersion of jute fibers. These properties can be optimized by adjusting the molding condition accordingly. For example, at a molding pressure of 1.33 MPa, the tensile strength achievement ratio of more than 85% can be attained if the molding temperature was kept between 190-195°C, while molding time should be maintained between 5-8 min.
