DYNAMIC FRACTURE-MECHANICS OF A RIM POLYAMIDE BLOCK COPOLYMER REINFORCED WITH GLASS STRAND MAT

The fracture behavior of a reaction injection molded (RIM) polyamide block copolymer reinforced with randomly arranged continuous glass fiber bundles (glass mats) was studied under dynamic loading conditions at T=RT and T=-40 °C. Dynamic fracture toughness, Kd, and fracture energy, Gd, values were derived from instrumented high-speed impact bending tests carried out on Charpy and Izod specimens of different size and notching direction, respectively. It was established that fracture mechanics data depend on the ligament width of the specimens. It was shown how the "inherent" flaws caused by machining and molding can be determined. Failure mode of the composites was characterized by fractography and possible failure events were summarized. Recommendations were given for further material improvements. © 1990 Springer-Verlag.