Studies of cure kinetics of polyisoimide by differential scanning calorimetry in the solid state

Abstract

AbstractDetailed kinetic studies of the thermal imidization of polyisoimide based upon 4,4′‐oxydianiline and 4,4′‐oxydiphthalic anhydride by differential scanning calorimetry are described. Both isothermal and dynamic methods have been used to obtain kinetic parameters and a phenomenological rate equation for estimating the degree of imidization as a function of time. The thermal imidization of polyisoimides in the solid state showed a maximum degree of imidization that can be achieved at a given isothermal temperature, probably due to the diffusion controlled characteristics of reactions near vitrification. That the reaction stopped near to the point of vitrification was considered when developing a phenomenological rate equation for thermal imidization of polyisoimide in the solid state. The thermal imidization is well described by modified first order kinetics with an activation energy of 170–181 kJ mol−1 and a pre‐exponential factor of 4.1 × 1013 s−1.© 2002 Society of Chemical Industry