GRAFT-COPOLYMERS AND IONOMERIC ASSOCIATIONS FROM MIXTURES OF PHENOXY WITH ACID FUNCTIONALIZED POLYOLEFINS .2. COMPATIBILIZERS FOR HDPE PET BLENDS/

Graft copolymers and coionomeric mixtures produced by mixing a phenoxy polymer (polyhydroxyether of bisphenol A) respectively with ethylene- propylene copolymers, containing grafted maleic anhydride groups (EP-g -MA), and the sodium ionomers of the terpolymers of ethylene, an alkyl acrylate and a carboxylic acid, the ionomeric character of which bein g enhanced by the addition of either sodium benzoate (weak base) or so dium ethoxide (strong base), were used as compatibilizers for blends o f PET and HDPE in different ratios and with varied molecular weight of the HDPE component. The preparation of the compatibilizer and the pro duction of the blends were carried out on a twin-screw extruder. Both types of compatibilizers acted as effective surfactants for the disper sion of the two polymers, at all weight ratios, and the blends exhibit ed a substantial increase in melt viscosity as a result of the additio n of the compatibilizer. Only the coionomeric compatibilizers, however , produced substantial improvements in both tensile strength and elong ation at break, irrespective of the ratio of the two polymers in the b lends. This was attributed to the strong nucleating effects on the cry stallization of the polymer components and to a strong interfacial adh esion between the two polymer phases. (C) 1994 John Wiley & Sons, Inc.