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 responsibl e for the gamma and beta secondary relaxations in unsaturated polyeste r networks. In DEG networks the gamma transition is assigned to restri cted phenyl group rotation in the Styrene cross-links whereas the moti on of molecular groups in the vicinity of the residual maleic double b onds account for the beta transition. (C) 1994 John Wiley and Sons, In c.