REACTION-INDUCED PHASE-SEPARATION IN A SEMIINTERPENETRATING NETWORK OF REACTIVE TERNARY BLENDS

Morphology and reaction mechanisms were probed on a model reactive ter nary blend system of polycarbonate (PC), poly(methyl methacrylate) (PM MA), and diglycidylether of bisphenol-A (DGEBA) epoxy by using differe ntial scanning calorimetry (DSC), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). Molecular interact ions/reactions between the components in the blends after heating trea tments are discussed. It was found that reactions took place among the components and that an interpenetrating network was built. The possib le reaction mechanisms and the resulting structures after the heating treatments were probed. In the blends, PC and DGEBA reacted to form a network, while PMMA remained free. The semiinterpenetration, however, did not result in a network interlocked into a homogeneous state. The single T-g of the heated ternary DGEBA/PC/PMMA blends actually did not reflect a homogeneous interpenetrating network. Due to relatively sma ll PMMA domains, the ternary blend network exhibited a single T-g. Upo n etching the PMMA domains from the blend by acetone, a clearly interp enetrating network of reacted PC and epoxy was exposed and confirmed. The reactions leading to such a morphology are discussed with experime ntal evidence. (C) 1996 John Wiley & Sons, Inc.