Phase separation in polysulfone-modified epoxy mixtures. Relationships between curing conditions, molphology and ultimate behavior

Chemorheology of curing as well as the phase separation behavior of polysul fone (PSU)-modified diaminodiphenylmethane-cured diglycidylether of bisphen ol-A epoxy mixtures have been studied using several techniques. The delay i n polymerization for the modified mixtures with respect to that of the neat epoxy can be explained by dilution and viscosity effects. The immiscibilit y of these mixtures has been proved for various PSU contents and as a funct ion of the precuring conditions used as well. The control of the generated morphologies can be performed only by varying the processing temperature. T he thermal and dynamic viscoelastic behavior of the modified matrices has b een examined and compared to the parent epoxy matrix. Finally, the mechanic al properties, including fracture toughness, have been discussed in terms o f the morphological behavior for an epoxy matrix modified with various amou nts of PSU and for a 15 wt.% PSU-containing matrix precured at different te mperatures. (C) 1999 Elsevier Science Ltd. All rights reserved.