Effect of solvent on the ultrasonic degradation of poly(vinyl acetate)

The ultrasonic degradation of poly(vinyl acetate) was carried out in six di fferent solvents and two mixtures of solvents. The evolution of molecular w eight distribution (MWD) with time was determined with gel permeation chrom atography. The observed MWDs were analyzed by continuous distribution kinet ics. A stoichiometric kernel that accounts for preferential mid-point break age of the polymer chains was used. The degradation rate coefficient of the polymer in each solvent was determined from the model. The variations of r ate coefficients were correlated with vapor pressure of the solvent, the Fl ory-Huggins polymer-solvent interaction parameter and the kinematic viscosi ty of the solution. A lower saturation vapor pressure resulted in higher de gradation rates of the polymer. The degradation rate increased with increas ing kinematic viscosity. (C) 2001 Elsevier Science Ltd. All rights reserved .