EFFECT OF IONIC INTERACTION ON ELONGATIONAL VISCOSITY OF ETHYLENE-BASED IONOMER MELTS

The effects of ionic interaction on the uniaxial extensional flow of p olymer melts were investigated using poly(ethylene-co-methacrylic acid ) and its metal (Zn, Na, Mg) salts. The presence of ionic bonding enha nced the elongational viscosity in the linear region and the degree of non-linearity. Both the linear and non-linear elongational viscositie s were increased more by zinc ions than by sodium or magnesium ions. T he order of elongational viscosities was in agreement with the order o f activation energies obtained from dynamic shear measurements. It was concluded that the increase in both linear elongational viscosity and non-linearity is determined by the degree of ionic interaction. The d ifferent flow properties between zinc and magnesium ionomers indicated that the ionic cluster formation weakens the ionic interaction. A Ber nstein-Kearsley-Zapas constitutive analysis revealed that the effect o f ionic interaction under elongational deformation in the linear regio n is similar to that under dynamic shear deformation.