Synthesis and processing of the (ethylene-vinyl acetate-vinyl alcohol) terpolymer and its blends with a polyamide and styrene copolymers

Abstract

In this article, the synthesis and properties of the (ethylene-vinyl acetate-vinyl alcohol) terpolymer are studied in detail. A transesterification reaction with alcohols was conducted on poly(ethylene-vinyl acetate) to obtain terpolymers with varying hydroxide contents through three different routes: in solution, in a mixing chamber, and in a twin-screw extruder. The kinetics of the reaction in the mixing chamber are compared with those of the twin-screw extruder. Mechanical and rheological properties of the terpolymer are examined as a function of conversion. Blends of the terpolymer with polyamide (Nylon-6) were prepared for various compositions. They show a steep reduction in the equilibrium torque with respect to that of the polyamide. A region of compatibility at high polyamide contents gives rise to an increase of some mechanical properties above the simple mixing rule (Young's modulus). On the other hand, blends with poly(styrene-acrylonitrile) and poly(styrene maleic anhydride) show a region of compatibility at equal proportions of the styrene copolymers and with 10% terpolymer content, induced by the reaction of the hydroxide and maleic anhydride groups. This reaction is inhibited at high styrene-acrylonitrile concentrations due to interference presented by the effect of interactions between the maleic anhydride and acrylonitrile groups. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1071–1083, 1998