MISCIBILITY AND CURE KINETICS OF NYLON EPOXY RESIN REACTIVE BLENDS/

The miscibility, phase behavior and cure kinetics of the reactive blen ds of an alcohol-soluble nylon with an epoxy resin, i.e. diglycidyl et her of bisphenol A (DGEBA), were studied by differential scanning calo rimetry (d.s.c.) and Fourier transform infra-red spectroscopy (FTi.r.) . Differential scanning calorimetry (d.s.c.) studies showed that all t he uncured nylon/DGEBA blends were crystallizable and exhibited two gl ass transition temperatures (T(g)s). The lower T, is independent of co mposition and is due to the glass transition of DGEBA phase. The highe r T-g varies with composition and is attributable to the glass transit ion of the nylon-rich phase. Nylon is partially miscible with DGEBA, a nd the extent of miscibility is dependent on the blend composition. Ny lon and DGEBA in all the uncured blends can react with each other abov e 200 degrees C. The curing reaction of nylon with DGEBA is dependent on the blend composition. The nucleophilic attack on oxirane ring by a mide nitrogen of nylon is dominant curing reaction in low DGEBA compos itions, and another type of curing reaction with relatively large acti vation energy and frequency factor also occurred which becomes dominan t when the DGEBA content reaches 63 wt% or more. FTi.r. studies reveal ed there does exist two types of reactions during curing of nylon with DGEBA. All the cured nylon/DGEBA blends show a composition-independen t T-g, which is the glass transition of cured nylon-DGEBA network. All other blends are uncrystallizable after curing except for the 90/10 a nd 80/20 nylon/DGEBA blends. The curing greatly destroyed the crystall inity of the blends. (C) 1998 Elsevier Science Ltd. All rights reserve d.