Ultrasonic Degradation of Polyvinyl Pyrrolidone (PVP): Effect of Power of Ultrasound, Temperature and Concentration

The ultrasonic degradation of polyvinyl pyrrolidone (PVP) was carried out in a range of different concentration of polymer solution to investigate on the changes of molecular weights. Also the ultrasonic degradation at different temperatures and power of ultrasound (30-150 W) was investigated. Most of the effects involved in controlling molecular weight can be attributed to the large shear gradients and shock waves generated around collapsing cavitation bubbles. The calculated rate constants indicated that the degradation rate of the PVP solutions decreased as the temperature increased. The average molecular weight of ultrasonicated PVP was determined by measurements of relative viscosity of samples. The degradation rate of this polymer was followed by a kinetic model based on viscosity measurements. Rate constants of ultrasonic degradation were calculated, and the results showed their dependence on polymer concentration.