Fabrication, evaluation and radiation behavior of S2-glass fiber reinforced polyimide laminates for cryogenic applications

A number of thermosetting polyimide resin formulations have been prepared evaluated and used in the resin transfer molding (RTM) fabrication of S2-glass reinforced composite laminates. The resin formulations are based on combining varying amounts of 3, 4'-oxydianiline and 4, 4-(1,3-phenylenedioxy) dianiline with 4, 4-bisphenol A dianhydride and 3, 3', 4, 4'-benzophenone tetracarboxylic dianhydride and terminated in 4-phenylethynyl phthalic anhydride. The initial viscosity and working life of the resins were measured to determine suitability for RTM. Composite laminates were prepared by degassing and then transferring the resins at 260 or 270 degrees C. A laboratory RTM system with process capabilities to 300 degrees C and 2000 psi, was built and utilized. The polyimide matrix was cured at 320 and 340 degrees C, with a dwell for 3 h at each temperature, under 280 psi hydrostatic pressure. The effect of three different Co-60 gamma irradiation doses on cryogenic (77K) mechanical and thermal properties was determined. Performance was compared to that of laminates prepared from a commercially available bismaleimide (RTM-651 (R)). The composites are being studied for their potential use as the electrical insulation in the super-conducting magnet coils of future fusion reactor devices such as the International Thermonuclear Experimental Reactor.