M. Franco et al., Blends of epoxy resin with amine-terminated polyoxypropylene elastomer: Morphology and properties, J APPL POLY, 72(3), 1999, pp. 427-434
A liquid diglycidyl ether of bisphenol A (DGEBA) epoxy resin is blended in
various proportions with amine-terminated polyoxypropylene (POPTA) and cure
d using an aliphatic diamine hardener. The degree of crosslinking is varied
by altering the ratio of diamine to epoxy molecules in the blend. The mixt
ure undergoes almost complete phase separation during cure, forming spheric
al elastomer particles at POPTA concentrations up to 20 wt%, and a more co-
continuous morphology at 25 wt %. In particulate blends, the highest toughn
ess is achieved with nonstoichiometric amine-to-epoxy ratios, which produce
low degrees of crosslinking in the resin phase. In these blends, the corre
lation between G(1C) and plateau modulus (above the resin T-g), over a wide
range of amine-to-epoxy ratios, confirms the importance of resin ductility
in determining the fracture resistance of rubber-modified thermosets. (C)
1999 John Wiley & Sons, Inc.