Effect of Temperature and Solution Concentration on the Ultrasonic Degradation of the Aqueous Solutions of Polyethylene Oxide

The ultrasonic degradation of polyethylene oxide (PEa) solutions was carried out in water at 20, 25, 30, 35 and 40°C to investigate the effect of temperature and solution concentration on the rate of degradation. Kinetics of degradation was studied by viscometry. The obtained limiting molecular weights indicate that under the conditions of increased temperature and solution concentration the degradation rate of PEa solutions decreases. The obtained limiting molecular weights were correlated in terms of concentration and temperature. The calculated rate constants also indicate that degradation rate of PEa solutions decreases as the temperature and solution concentration are increased. The calculated rate constants were correlated in terms of concentration, temperature, and molecular weight of polymer. This degradation behaviour was interpreted in terms of vapour pressure of water, viscosity, and concentration of polymer solutions. With increasing temperature, the vapour pressure of solvent increases and as this vapour enters inside the growing cavitation bubbles there is a reduction in collapsing shock due to the developed cushioning effect. As a result, the rate of degradation decreases. As the solution concentration increases, the viscosity increases, leading to reduced cavitation efficiency and therefore the rate of degradation decreases.