SOLID-STATE NMR INVESTIGATION OF CROSS-LINKABLE BLENDS OF NOVOLAC ANDPOLY(EPSILON-CAPROLACTONE)

The miscibility, phase behavior, and intermolecular interaction of nov olac/poly(epsilon-caprolactone) (PCL) blends, before and after curing, were investigated by the high resolution solid-state nuclear magnetic resonance (n.m.r.) technique. It was found that there exists hydrogen -bonding interaction between the carbonyl groups of PCL and the hydrox yl groups of novolac, which results in the downfield shift of carbonyl carbon resonance of PCL and the upfield shift of hydroxyl-substituted carbon resonance of novolac. The interaction also broadens the line w idth of carbonyl carbon resonance. After curing with 15 wt% hexamine ( relative to novolac content), hydrogen-banding interaction still exist s between the components in the crosslinked blends. However, the relat ive amount of hydrogen bonds decreases significantly. Both the uncured and the cured novolac/PCL blends exhibit composition-dependent miscib ility. The curing causes an increase of the domain size in the amorpho us phase and a reaction of miscibility between the two components. (C) 1998 Elsevier Science Ltd. All rights reserved.