The crosslinking of epoxy resins at interfaces. II. At an aromatic polyamide surface

Abstract

Abstract The first 200–400 nm of crosslinked epoxy resin adjacent to an aromatic polyamide (aramid) surface were characterized by internal reflection spectroscopy (IRS) using an aramid‐coated IRS element. The crosslinking kinetics and final crosslinked state of an anhydride‐cured epoxy resin were strongly affected by the aramid surface, which produced a localized increase in the rate of anhydride consumption and a decrease in the yield of ester products. An aromatic amine‐cured epoxy resin was less affected by the aramid surface. Unidirectional aramid fiber:epoxy composites were examined by dynamic mechanical analysis (DMA), and differential scanning calorimetry (DSC). The chemical changes detected spectroscopically were shown to correlate with mechanical and thermal transition data obtained by DMA and DSC. These results are rationalized on the basis of the effect of absorbed moisture in the aramid on the crosslinking chemistry.