Toughening Mechanisms of Long-Fiber-Reinforced Thermoplastics

Various toughness properties were compared between long-glass-fiber-reinforced thermoplastics and their short-fiber counterparts in an effort to understand the toughening mechanisms of the long-glass fibers in reinforced thermoplastics. It was found that long-glass fibers improve the toughness of polypropylene- based composites by rendering more resistance to fiber debonding and subsequent pull-out, especially at subambient temperatures. For nylon-based composites, which form strong fiber/matrix interfaces, long-glass fibers were found to increase the toughness by imparting more resistance to fiber breakage. Finally, fiber orientation was found to have a significant effect on the fracture toughness of reinforced thermoplastics.