Thermal models for MTM45-1 and Cycom 5320 out-of-autoclave prepreg resins

Out-of-autoclave prepregs require a two-step cure cycle. The first step is a low temperature cure to consolidate the laminate and build sufficient green strength to proceed to the second step, a free-standing post-cure at traditional autoclave temperatures to fully cross-link the resin. Process modeling can help design a robust cure cycle to avoid scrapping large parts in production. The focus of this article is to develop the cure kinetics, viscosity, and glass transition temperature models for two commercially available out-of-autoclave epoxy resins. Since the cure kinetics model is the basis for all other thermal models, the cure kinetics model was validated using a one-dimensional heat transfer analysis on thick prepreg laminates. Finally, the out-of-autoclave resin models were compared to a traditional autoclave resin system to highlight the difference in resin reactivity for out-of-autoclave processing.