Weld strength of injection molded short fiber reinforced polypropylene

Fiber reinforced thermoplastics (FRTPs) are used for lightweight automobile and home appliances because of their higher specific strength and modulus compared to other materials. Although injection molding is often used in FRTPs considering productivity, an important difficulty is that the strength is reduced considerably by the weld joining the resin. This study investigated the fiber content dependence on the weld strength of injection molded fiber-reinforced polypropylene (FRP). Results suggest a negative correlation between the fiber content and weld strength. Experimentally obtained results also clarified that the FRP weld strength can be determined by the residual strain derived from thermal deformation during molding processing and the interaction force between the fiber and the matrix.