Electron-Beam (E-Beam) Processing as a Means of Achieving High Performance Composite Structures

Report No. ARL-TR-2613
Authors: James M. Sands, Steven H. McKnight, Bruce K. Fink, Anna Yen, and Giuseppe R. Palmese
Date/Pages: November 2001; 74 pages
Abstract: Electron-beam (E-beam) curing is among the key out-of-autoclave technologies being explored for future advanced composite and adhesive applications. E-beam irradiation curing is capable of rapid and through-thickness curing of composite samples up to 2-in thickness, eliminating the need for long cure cycles in the autoclave. However, current resin and adhesive chemistries are optimized for cure by thermal initiation, which involves slow ramps and long cure cycles, particularly for thermoset composites based on epoxides. Therefore, in order to provide improved performance in composite systems cured by E-beam irradiation, a program was undertaken to investigate performance and formulation effects in two E-beam curable systems. One system, a free-radical-cured acrylic system, introduces the concept of interpentrating network structures as a means of meeting performance requirements in E-beam-processed composites. The second resin system incorporates cationic curing of epoxides induced through Lewis acid or cation generating initiators. Additionally, a new approach to toughened interpenetrating polymer networks (IPNs) based on simultaneous cure using both free-radical and cationic-cure mechanisms is proposed along with initial experimental characterizations. The results of formulation and processing modifications on key properties of adhesives, resins, and composites structures are demonstrated.
Distribution: Approved for public release
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Last Update / Reviewed: November 1, 2001