ATTACHING OF FLEXIBLE CHAINS TO NOVOLACS ON THE BASIS OF BISPHENOL-A

Networks containing both flexible segments and rigid structures were s ynthesized on the basis of bisphenol A novolacs and diglycidylether of butanediol using imidazole as an accelerator. A stoichiometric ratio between epoxy groups and phenolic groups of the novolacs leads to netw orks with methylene bridges as network junctions. In contrast to this, the same reaction with bisphenol A leads to completely soluble produc ts. The glass transition temperature of this soluble material is consi derably lower than the glass transition temperature of the networks. I ncreasing content of methylene bridges in the novolacs leads to an inc rease of the glass transition temperature of the networks and to a dec rease of the Delta c(p) value at the glass transition. Furthermore, ep oxy excess leads to networks with rubberlike properties. In addition, AM1 calculation were performed to optimize the geometric structure of the bisphenol A novolac used in the reaction with the diglycidylether. It was found that conformations with intramolecular hydrogen bondings exist between phenolic hydroxyl groups, which considerably influence the reactivity of the novolac with the epoxy group. (C) 1996 John Wile y & Sons, Inc.