Title Electron-Beam Processable Polyimides for High-Performance Composite Applications
Source Proc. 46th Intl. SAMPE Symp. and Exhib.
Year 2001
Author(s) Hoyt, A. E.
Abstract Electron beam (e-beam) curing of polymer matrix composites (PMCs) is highly desirable from a manufacturing standpoint in that significant cost savings may be realized from the reduced cycle times, the ability to cure large and irregularly shaped parts, and the ability to use inexpensive tooling. However, for many applications in the aerospace and transportation industries, e-beam processable resins currently available do not meet the performance specifications (e.g., excellent thermal stability, high strength, and high toughness). Adherent Technologies, Inc. has recently been developing linear, low molecular weight polyimides with functionalities amenable to cross linking under electron beam irradiation. A soluble, fully-imidized polyimide backbone was used as the basis for all materials prepared. Oligomers of several different molecular weights were prepared and end-capped with functionalities amenable to electron beam-induced cross linking reactions. A carbon fiber-based tape impregnated with the most promising resin was prepared and exposed to electron beam irradiation at a total dose of approximately 150kGy. Thermomechanical analysis of unexposed tapes showed considerable compression of the sample at temperatures as low as 150°C. In contrast, the e-beam exposed samples showed less resin softening and less compression during analysis. Glass transition temperatures in the exposed samples were also higher (240°C to 250°C). Current efforts focus on improving polyimide processability for automated tape placement (ATP) and on increasing functionality in the system to afford a better cure.
Keywords e-beam curing, polyimide, polymer matrix composites, PMC, Oligomers, automated tape placement, ATP