Impacts of Molding Pressure on Performances of Kraft Fiber Reinforced Unsaturated Polyester Composites

Abstract

Novel Kraft fiber reinforced unsaturated polyester (UPE) composites were prepared at various molding pressures in order to investigate the effects of molding pressure on resin content, the mechanical properties and creep resistance. The results indicated that the novel composites had much higher mechanical properties and better creep resistances than traditional wood plastic composites because of the applications of strong Kraft fibers as reinforcement and thermosetting UPE as matrix. Molding pressure had various effects on the many properties of composites. With molding pressure increased from 6MPa to 25MPa, the mechanical properties and creep resistances increased gradually until about 20MPa and then decreased, which were attributed to the different interface adhesions between UPE resin and Kraft fibers at various molding pressures as evidenced by DMA analysis. Benefited from the use of low-viscosity UPE resin, the resin content of Kraft fiber reinforced UPE composites could reduce to 28.3% while strength and creep resistance were still much better than that of the thermoplastic wood-plastic composite (WPC) with 40% polymer matrix.