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Abstract
The cure kinetics of bisphenol-S epoxy resin (BPSER) and curing agent phthalic anhydride, with N,N-dimethyl phenzylamine as an accelerator, were studied by means of differential scanning calorimetry (DSC). Analysis of DSC data indicated that an autocatalytic behavior showed in the first stages of the cure. The autocatalytic behavior was well described by the model proposed by Kamal including two rate constants, k1 and k2, and two reaction orders, m and n. The overall reaction order, m + n, is in the range 2∼3. The activation energies for k1 and k2 were 111.69 and 80.47 KJ/mol, respectively. Diffusion control was incorporated to describe the cure in the latter stages. The glass transition temperatures (TgS) of the BPSER/anhydride samples isothermally cured partially were determined by means of torsional braid analysis (TBA). and the results showed that the reaction rate increased with increasing Tg in terms of the rate constant, but decreased with increasing conversion. The Tg of completely cured BPSER/anhydride system is about 40 K higher than that of BPAER. The thermal degradation kinetics of this system was investigated by thermogravimetric analysis (TGA). It illustrated that the thermal degradation of the BPSER/phthalic anhydride has n-order reaction kinetics.
