p. 1019-1023
We investigate the mechanical behavior of the fiber reinforced organic composites in high vacuum and temperature condition. The material used in this study is short carbon fiber reinforced thermoplastic polyimide composites (SCFR-PI) with various fiber contents. Tension tests were carried out with the aid of AE method. After the tests, we observed the damage propagation in SCFR-PI specimens by scanning electron microscope photographs and optical microscope photographs. The main results are summarized, as follows: (1) Even though tested at the same temperature 298 K (25℃), the SCFR-PI composite specimen kept in high vacuum condition has higher tensile strength and higher equivalent Young's modulus than that in the atmospheric condition. (2) The fiber pull-out length of the specimen in high vacuum condition is shorter than that in the atmospheric condition and the fracture surfaces are not flat. The strength of the interfacial bonding between carbon fibers and the thermoplastic polyimide resin matrix becomes better in high vacuum condition. The degas and/or moisture desorption may change the performance of each materials and microfractures of SCFR-PI composites. (3) It is found that there exists the effect of vacuum condition on the tensile strength and Young's modulus of SCFR-PI composites and the microfractures.
