Abstract:

In order to obtain long fiber reinforced thermoplastic composites with high weight ratios and high degrees of orientation, a stretch-breaking process was adopted to prepare glass fibers (GF) and polypropylene (PP) filaments into bi-component slivers. The slivers were aligned in two perpendicular layers, and the resulted hybrid-fiber was subjected to hot pressing to form GF/PP long fiber reinforced thermoplastic composites. The morphology of the composites was observed, and their static and dynamic mechanical properties were characterized by using the tensile test, bending test, impact test, and dynamic mechanical analysis (DMA). The test results show that glass fibers with an average length of 22.9 mm has high straightness, highly oriented and dispersed in the PP matrix, and accounts for 45.73% of the composites. Glass fibers are fully saturated in the matrix, which provides the composites with a porosity of 1.58%. In comparison of composites prepared by extrusion molding and stretch-breaking process, the latter obtain greater mechanical properties. DMA results show that the glass transition temperature of composites is 73.4 ℃, and the composites retain good thermomechanical properties at 150 ℃ and maintain high storage modulus and small loss factor.

Key words: thermoplastic composite, hybrid fiber preform, glass fiber, polypropylene fiber, mechanical property