COIONOMERIC MIXTURES OF POLYHYDROXYETHERS AND ETHYLENE METHACRYLIC-ACID COPOLYMERS .2. COMPATIBILIZERS FOR BLENDS OF POLYBUTYLENE TEREPHTHALATE AND ETHYLENE BUTYL ACRYLATE COPOLYMERS

Blends of polybutylene terephthalate and ethylene butyl acrylate copol ymers were studied at two extreme concentration levels so that each po lymer would form, in turn, a particulate dispersed phase. The blends c ontained 5% by weight of a coionomeric compatibilizer, which was produ ced from 1 : 1 mixtures of a polyhydroxy ether of bisphenol A and the sodium ionomer of an ethylene methacrylic acid copolymer, using sodium ethoxide to enhance the formation of ionomeric clusters together with an A-B-A block oligomer to assist the solubilization of the two ionom eric polymers. In all cases the addition of the coionomeric compatibil izer mixture to the blend was found to decrease the size of the disper sed particles with a concomitant reduction in the interphase gap. It w as also observed that the dispersed polymer exhibited a lower level of crystallinity and a slightly lower melting point than when it was pre sent as a matrix, particularly for the case of the ethylene butylacryl ate copolymer. The inability of the compatibilizer to completely preve nt the formation of an interfacial gap which did not allow the blends to achieve more substantial improvements in mechanical properties, was attributed to the vast difference in crystallization temperature betw een the two polymers. (C) 1993 John Wiley & Sons, Inc.