Processability of DDS isomers-cured epoxy resin: Effects of amine/epoxy ratio, humidity, and out-time

Three aerospace grade resins were formulated to investigate the effects of variation in DDS isomers, amine-to-epoxy (a/e) stoichiometric ratio, out-time, and moisture absorption on processing characteristics and cured resin properties. Such resins are typically used in prepreg or preimpregnated composite fibers, which require engineered processing methods to fully impregnate the fiber bed during cure. Precure phenomena, specifically out-time and moisture absorption, are generally unavoidable in practice, and these phenomena were investigated to determine the relationship between DDS isomers, a/e stoichiometric ratio, out-time, and moisture absorption on processing characteristics and cured resin properties. Furthermore, predictive models were developed to provide insights into defect formation mechanisms and mitigation strategies for prepreg processing. POLYM. ENG. SCI., 58:1530-1538, 2018. (c) 2017 Society of Plastics Engineers