INTERFACIAL REACTIONS IN CARBON EPOXY COMPOSITES

A series of models for carbon-epoxy interphase are developed comprising high surface area carbon blacks, crushed carbon fibers and chopped carbon fibers in epoxy matrices. The carbon surfaces are modified by oxidative or reducing treatments and the effects of the modified carbon surfaces on the epoxy cross-linking processes are examined by differential scanning calorimetry and infrared spectroscopy. Oxidized carbon surfaces retard the cure of the anhydride-epoxy systems by adsorption of the tertiary amine catalyst. Oxidized carbon surfaces initially accelerate epoxy-amine reactions but inhibit the later stages of the reaction such that the final level of cure is reduced.