Effect of poly(styrene-co-acrylonitrile) on the curing of an epoxy/amine resin

The cure kinetics and the miscibility have been studied in blends of poly(styrene-co-acrylonitrile) (SAN) with tetraglycidyl-4,4′-diaminodiphenylmethane (TGDDM) and 4-4′-diaminodiphenylsulphone (DDS) as hardener. Differential scanning calorimetry (DSC) was the technique used for dynamic and isothermal experiments. Binary mixtures of SAN with the epoxy resin show complete miscibility over the whole composition range, displaying a single glass transition temperature. Kinetic analysis were performed using three kinetic models: Kissinger, Flynn–Wall–Ozawa and the phenomenological model developed by Kamal. Activation energies and kinetic parameters were determined by fitting experimental data. Diffusion control is incorporated to describe the cure in the latter stages, predicting the cure kinetics over the whole range of conversion. The autocatalytic mechanism was observed for the neat system and the epoxy-SAN blends. The reaction rates for the epoxy blends were found to be lower than of the neat epoxy. The reaction rates and the maximum conversions decreased when SAN contents increase, due to reduction of mobility of the reacting species.