EFFECTS OF PRESS PRESSURE ON THE MECHANICAL PROPERTIES OF RIB ROOT FOR GLASS FIBER REINFORCED POLYPROPYLENE COMPOSITES, MOLDED BY PRESS AND INJECTION HYBRID MOLDING

The press and injection hybrid molding system, which is a novel molding technology with the combination of press molding and injection molding, is expected for the production of FRTP (Fiber Reinforced Thermoplastics) with complicated shapes and high levels of stiffness and strength. Press and injection hybrid molded structures consist of an outer shell laminate of continuous fiber and injected short or long fiber reinforced thermoplastics which form the rib structure. The higher mold temperature was reported to increase the strength of the interface between the outer shell laminate and injected material. On the other hand, the penetration of continuous fibers of the outer shell laminate into the rib structure decreases the mechanical properties of the outer shell laminate. While the effects of mold temperature on the mechanical properties of hybrid molded composites were clarified, the effects of press pressure have not been clarified yet. In this study, the effects of the press pressure on the mechanical properties of the outer shell laminate and interfacial strength between the outer shell laminate and injected material were evaluated. As the lower press pressure decreases, the penetrated height of continuous fiber into the rib structure, higher in-plane tensile strength and lower interfacial strength, are obtained.