Polyimide Matrix Composites: Candidates for High Speed Commercial Aircraft or not?

Abstract

Several aerospace companies are actively pursuing the development of a 'high speed civil transport aircraft' (HSCT). Flight profiles and weight considerations dictate the use of high temperature advanced composites. This paper briefly examines two such contenders-PMR-15 and bismaleimides (BMIs). Materials are compared in the categories of thermo-oxidative stability, resistance to thermal cycling, damage tolerance, toxicity and ease of fabrication. At present, it would appear that neither PMR-15 nor BMIs, in general, are capable of meeting HSCT requirements. PMR-15 seems to be hampered by its susceptibility to microcracking, monomer toxicity and difficult fabrication. On the other hand, the use of BMIs seems to be hampered by their relatively poor thermo-oxidative stability. These views assume an aircraft with a maximum operating temperature of about 350°F. Should this requirement change, then the picture will change also and other materials could be considered.