Stageable resins for electron beam cured composites manufacture

Among the key requirements for achieving cost savings advantages by electron beam cure technology is the ability to maintain low tool costs, and to maintain structural integrity of the composite laminates, including consolidation and net shape, while allowing e-beam processing. One approach to achieving highly controlled par configurations is to use two-stage electron beam cured interpenetrating polymer network resins (IPNs). The Army in conjunction with the Drexel University is developing vacuum moldable resins for that can be c-stage cured to near net shape parts at room temperature, but which are further processed using e-beam to achieve thermal stability and high-performance composite specifications. Among the technologies demonstrated are epoxy-amine staged laminates with free radical methacrylate cured resin as an e-beam crosslinked network. The advantages of this two-stage curing include increased control over consolidation of laminates, low-cost tooling requirements, and excellent thermal performance in the composite laminates. The resin systems produced provide an environmentally favorable alternative to many thermal cured systems, by providing increased resin out-times, increased storage life, and reduced volatile organic emissions on curing. Further, the resin systems are ideal for adhesive applications, where bonded structures can be held together via c-staging of the IPN adhesives, allowing complex shapes to be bonded and then further cured to high performances using electron beam irradiation. The general structure of the IPNs and the performance of the epoxymethacrylate resin systems will be presented along with composite performance specifications.