COST-EFFECTIVE MANUFACTURING OF NATURAL FIBER TEXTILE COMPOSITES FOR SEMI-STRUCTURAL APPLICATIONS BY DIRECT THERMOPLASTIC MELT IMPREGNATION

摘要

We developed a new manufacturing technology for flax fiber textile reinforced thermoplastic composites by direct impregnation method in a closed mold. To reduce the resin flow path during the highly viscous resin impregnation process, the fiber textile reinforcement was partially impregnated and then the stack of fiber reinforcement and polymer melt was compressed by the mold platen. Optimal process temperature conditions such as mold temperature, resin temperature and fiber temperature, were experimentally determined while avoiding the thermal degradation of flax fiber and obtaining good impregnation quality. In particular, a sequential pressure cycle was proposed to improve the impregnation quality and to obtain the uniform fiber volume fraction in the final part. The impregnation quality was assessed by the density measurement and by the micrographic image analysis. The mechanical properties of the final parts were comparable with the literature values obtained by the compression molding of matrix-fiber premixed materials such as commingle yarns or film stacking, whereas the process cycle time was order of several minutes which was much shorter than the other conventional methods in the literature and may be acceptable in the automotive industry.