EFFECT OF THERMAL-DEGRADATION ON THE MECHANICAL-PROPERTIES OF A DIGLYCIDYL ETHER OF BISPHENOL-A 1,3-BISAMINOMETHYLCYCLOHEXANE (DGEBA 1,3-BAC) EPOXY-RESIN SYSTEM/

The effect of thermal degradation on the mechanical properties of a di glycidyl ether of bisphenol A (DGEBA)/1,3-bisaminomethylcyclohexane (1 ,3-BAC) epoxy system, cured with two different curing cycles-a short c ycle and a long cycle-were studied using tensile and Izod impact exper iments and scanning electronic microscopy, SEM, observations. From the se experiments it can be noted a loss of mechanical properties of the material cured with both cycles with aging time, although the material cured with the long cycle presents better properties at any aging tim e. This better behavior can be explained from the time temperature tra nsformation, TTT, diagram of this system. A good correlation was obser ved between the decrease in the intensity of the peak of beta transiti on in tan delta curve obtained by dynamic mechanical analysis, DMA, an d the decrease of the Izod impact strength when thermal aging is incre asing. Also, a good correlation can be found between the increase in t he fragility of the material with aging time and the morphology of fra ctured surfaces observed by SEM. (C) 1997 John Wiley & Sons, Inc.