MISCIBILIZATION OF TELECHELIC FLUOROALKENEOXIDE OLIGOMERS IN EPOXY-RESINS AND EFFECTS ON MORPHOLOGY AND PHYSICAL-PROPERTIES

Hydroxyterminated fluoroalkene oxide oligomers were reacted with chlor endic anhydride and subsequently with epsilon-caprolactone to produce carboxyterminated perfluoroethers prepolymers that were totally miscib le with diglycidylether of bisphenol A. Curing the epoxy resin mixture s with hexahydrophthalic anhydride hardener and benzyl dimethylamine c atalyst produced transparent products exhibiting a two-phase co-contin uous morphology. Prereacting the fluoroalkeneoxide prepolymers with an excess of epoxy resin prior to the addition of hardener and catalyst, resulted in opaque products displaying a two-phase dispersed particle s morphology. The dynamic mechanical spectra of the cured products con firmed the absence of any significant short-range network miscibility and revealed substantial enhancements in beta-relaxations in all cases , which are normally associated with microdispersed morphologies. Both systems exhibited much higher flexural strength and ductility than th e equivalent unmodified epoxy resins, even at very low levels of addit ion, 3.5-5.0%. The surface energy was found to be much lower than that exhibited by the unmodified resin system, and the reduction in water absorption was relatively small. The above effects were much more pron ounced for products exhibiting a particulate morphology than for syste ms that exhibited a co-continuous morphology. (C) 1994 John Wiley & So ns, Inc.