Interfacial effect of urethane film former for glass fiber in polycarbonate and polypropylene composites

Interfacial reinforcement with urethane binder (UB) was investigated in a couple of thermoplastic composites: glass fiber / polycarbonate (GF/PC) and glass fiber / polypropylene (GF/PP). In the surface treatment, silane used as another agent was aminopropyltriethoxysilane (APS). Glass fiber was treated with UB+APS, UB, or APS. Short-length glass fiber treated with each agent was applied to thermoplastic composites using an extruder and an injection molder. In tensile test, UB was effective in GF / PC, but ineffective in GF/PP. In order to clarify the difference of interfacial effect with UB, the diffusion of UB to resin was analyzed by microscopic FTIR spectroscopy. As a result, the diffusion to PC appeared, while that to PP was not observed. In addition, APS depressed the diffusion of UB in PC including GF with APS+UB. These results suggested that the interfacial reinforcement needed not only the interaction between film former and resin, but also the interaction between silane and film former to produce the mechanical linkage from resin to fiber.