Heat Resistant Adhesion and Melt Rheology of the Polymer Complex between lonomer and Polyamide Oligomer

Abstract

Polyamide chain was introduced in the Zn ion ionomer made from ethylene-methacrylic acid copolymer and its effect on the heat resistant adhesive properties was investigated. The heat resistant temperature of the ionomer was enormously improved by compounding 5-20wt% of polyamide oligomer with primary amino end group into the ionomer. The resulting composite was thermoplastic and exhibited unusual thermo-adhesion behavior. Although the composite was capable of thermo-adhesion at the temperature as low as that for the component ionomer, it did not creep significantly up to the temperature considerably higher than the adhesion temperature.To clarify the cause and mechanisms of this unusual function, rheological measurements were made on the composite. The following features were revealed. The composite exhibited highly non-Newtonian flow behavior in the temperature range between the melting point of the component ionomer (85-105°C) and that of polyamide oligomer (180-215°C). The viscosity of the composite was much higher than that of the ionomer at low shear rates, leading to the improved heat resistant adhesive properties. With increasing shear rates, the viscosity of the composite decreased down to that of the ionomer, leading to the ease of thermo-processing and adhesion of the composite.In the composite, ammine complex salt was formed between Zn ionomer and polyamide oligomer through coordination of amino end group of the latter to zinc carboxylate of the former. In the above-mentioned temperature range, microphase-separated structures were formed in the composite. The solid phase microdomains of polyamide chains were dispersed in molten matrix of ionomer, and these phases were connected by coordination ionic bond. The thermoplastic and non-Newtonian behavior of the composite resulted from the destruction of the microdomains under high shear rates and the decrease of the ionic bond strength under high shear rates and high temperature.