MECHANICAL-PROPERTIES OF UNSATURATED POLYESTER RESINS IN RELATION TO THEIR CHEMICAL-STRUCTURE .1. SECONDARY RELAXATIONS AND LOCAL MOTIONS

Dynamic mechanical spectroscopy has been combined with high-resolution solid-state C-13 NMR to characterize the molecular motions responsible for the gamma and beta secondary relaxations in unsaturated polyester networks. In DEG networks the gamma transition is assigned to restricted phenyl group rotation in the Styrene cross-links whereas the motion of molecular groups in the vicinity of the residual maleic double bonds account for the beta transition. (C) 1994 John Wiley and Sons, Inc.