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Many fiber-reinforced composite systems have been given considerable attention for potential aerospace and advanced ship applications. This is primarily because of the superior specific modulus and tensile strength the composite materials exhibit. For many applications conventional polymer matrix materials such as polyesters and epoxies are not suitable since they have maximum use temperatures of only 90°C to 120°C. Recently, many “high performance polymers”, which offer 170°C to 260°C temperature capability, have become available. These include tetrafunctional epoxies, thermosetting polyimides and some thermoplastic polymers such as polysulfone. One of the important mechanical properties that need to be evaluated for these polymers is their resistance to crack propagation. Bascom, Bitner and Cottingtonl determined the fracture energy of many high performance polymers and concluded that the thermoplastics are much “tougher” than the thermosetting materials. While this would certainly be translated into superior impact properties, the thermoplastics are also attractive because they can be formed easily and possess good storage and handling capability at room temperatures. In this paper, the rate-dependent fracture behavior of two high performance sulfone polymers is reported. |
