Miscibility, crystallization behavior and specific intermolecular interactions in thermosetting polymer blends of novolac epoxy resin and polyethylene glycol

Thermosetting polymer blends of novolac epoxy resin (EPN) and polyethylene glycol (PEG) were studied. The miscibility and crystallization behavior of the blends before curing reaction were investigated by polarized optical microscopy and differential scanning calorimetry (DSC). Overall uncured blend compositions were homogeneous in amorphous state. Single composition‐dependent glass‐transition temperature (Tg) for each blend could be observed, and the experimental Tg's of blends with EPN content ≥40 wt% could be explained well by the Gordon–Taylor equation. Thermal properties of blends cured with 4,4′‐diaminodiphenylmethane were also determined by DSC. The capability of PEG to crystallize in cured blends was different from that in uncured ones because of the topological effect of highly crosslinking structure. On the basis of Fourier transform infrared spectroscopy results, it was judged that there were intermolecular hydrogen‐bonding interactions between EPN and PEG in both cured and uncured blends. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers