Rheological and calorimetric characterization of an epoxy system cured in presence of a reactive polyethersulphone

Curing and gelation of tetraglycidyl-4,4'-diaminodiphenyl methane epoxy res in (MY 720) in the presence of an amine functionalized thermoplastic PES wa s studied by dynamic rheological and calorimetric measurements. The gel poi nt was determined theologically and the apparent activation energy of the c uring reaction was determined by means of both rheology and differential sc anning calorimetry. By the dynamic rheological measurements under isotherma l conditions the gel time was found to vary with the curing temperature and the composition of the system. It was found that the amine functionalized thermoplastic PES works as a curing agent for the epoxy resin but the react ion is less pronounced and the apparent activation energy higher than that of the control system. However, using the amine functionalized thermoplasti c PES together with the conventional DDS curing agent, a synergistic effect is observed as a result of the greater number of activated molecules respo nsible for the crosslinking reaction. Moreover, in order to analyze the mic rostructure-properties relationship in the modified epoxy systems, SEM obse rvation was carried out on the fracture surfaces of the reactive PES contai ning epoxy resin.