Effect of HCl and solution concentration on the ultrasonic degradation of aqueous solutions of poly (ethylene oxide)

Abstract

The ultrasonic degradation of poly (ethylene oxide) solutions was carried out in aqueous solution of hydrogen chloride at 25°C to investigate the effect of HCl and solution concentration on the rate of degradation. The obtained limiting molecular weights and apparent rate constants indicate that the extent and rate of degradation of poly(ethylene oxide) solutions were decreased by increasing concentration of HCl from 0 to 0.3 M, and the extent and rate of degradation of poly(ethylene oxide) solutions were increased by increasing concentration of HCl from 0.3 to 0.5 M. The obtained limiting molecular weights were correlated in terms of concentration and initial intrinsic viscosity. The calculated rate constants were correlated in terms of concentration, initial intrinsic viscosity and molecular weight of polymer. This degradation behavior was interpreted in terms of initial intrinsic viscosity and concentration of polymer solutions. Intrinsic viscosity of poly (ethylene oxide) was decreased by increasing concentration of HCl from 0 to 0.3 M and the chains of polymer coiled and this caused a decrease in shear strain; therefore, the rate of degradation was decreased. But the chains of polymer were expanded by increasing concentration of HCl from 0.3 to 0.5 M and this caused an increase in shear strain; therefore, the rate of degradation was increased. As the solution concentration increased, the viscosity was increased and caused a reduction in the'cavitation efficiency, and so the rate of degradation is decreased.