STUDIES ON CURE CHEMISTRY OF NEW ACETYLENIC RESINS

This paper describes cure studies of arylacetylene-terminated resins to gain some fundamental understanding of the influence of various structural aspects of a molecule on its cure chemistry. Of particular interest are the effects of the number of acetylenic substituents on the aromatic ring and their relative positions to one another. Activation energy (E) of the cure reaction as calculated from dynamic DSC analysis reveals that there is a direct correlation between the activation energy and the stability of radicals formed by thermal initiation. Based on model compound studies, it is evident that the resonance stabilization of radicals contributes significantly to the lowering of activation energy values. When the number of substituents on the aromatic ring varies, the combined influence of resonance, inductive, proximity, and steric factors needs to be considered. Studies with blends of acetylenic monomers suggest that the possible chain-initiating species are those radicals which can be stabilized by resonance. From the DSC data, we also infer that the radicals formed initially may not be very selective in the reaction with other multiple bonds in their vicinity.