Systematic differential scanning calorimetry studies of the cure of carbon fiber - epoxy composite prepregs

High performance C fiber-epoxy composite laminates are fabricated from uncured C fiber-epoxy prepreg material. Diaminodiphenyl sulfone (DDS) cured tetraglycidyl 4,4' diaminodiphenyl methane (TGDDM) epoxies, whose cure reactions are accelerated by BF/sub 3/:amine catalysts, are the most common composite matrices utilized in these high performance composites. To process reproducible composites requires an understanding of the cure reactions and how these reactions are modified by the BF/sub 3/:amine catalysts. In this paper we report systematic differential scanning calorimetry (DSC) studies of the constituents of BF/sub 3/:NH/sub 2/C/sub 2/H/sub 5/ catalyzed TGDDM-DDS epoxies and their mixtures; the effect of BF/sub 3/:NH/sub 2/C/sub 2/H/sub 5/ concentration on the cure reactions; the nature of the catalyzed cure reactions and the environmental sensitivity of the catalyst. DSC studies are also reported on the cure reaction characteristics and environmental sensitivity of commercial C fiber-TGDDM-DDS epoxy prepregs.