Abstract: | The conformation of network chain segments in a rigid glassy DDM-cured bisphenol A epoxy resin has been determined by means of rotational isomeric-state model and confirmed by conformity of experimental NMR second moments with a theoretical estimate based on the model. The glass transition temperatures Tg have been determined from precipitate NMR line narrowing with increase in temperature due to the onset of rapid (>104 Hz) main-chain molecular motion. The temperature dependence of the correlation frequency has been determined and the type and extent of molecular motion that occurs in such epoxy resins is discussed. |