Mechanical properties of unsaturated polyester resins in relation to their chemical structure. I. Secondary relaxations and local motions

Dynamic mechanical spectroscopy has been combined with high-resolution solid-state ¹³C NMR to characterize the molecular motions responsible for the γ and β secondary relaxations in unsaturated polyester networks. In DEG networks the 7γ 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 β transition. © 1994 John Wiley & Sons, Inc.