Toughening of trifunctional epoxy system. V. Structure-property relationships of neat resin

This work presents an investigation into the structure-property relationshi ps of a cured highly crosslinked epoxy/amine resin system. The mechanical, physical, and thermal properties of the cured and postcured networks were m easured and compared to the chemical structures. Crosslink density was show n to he dependent upon secondary amine conversion and it determined the gla ss transition temperatures, water uptake, density, toughness, and compressi ve strength. Other properties such as compressive modulus and yield stress were determined by more short-range molecular motions. Curing at a temperat ure of 150 degrees C was shown to be the minimum temperature required to "c ompletely" cure the network and achieve optimum mechanical, physical, and t hermal properties. (C) 2000 John Wiley & Sons, Inc.