Quantification of frequency dependence of mechanical effects induced by ultrasound

The physical or mechanical effects induced by ultrasound were investigated through the viscosity change in degradation of polymers. The viscosity change was observed with polyethylene oxide in both aqueous and benzene solution; while polystyrene in only benzene solution. The frequency of ultrasound in these experiments varies from 20 kHz to 1 MHz, under a constant dissipated power. The viscosity ratio and the apparent degradation rate were obtained as a function of the irradiation frequency. From the analysis of these experiments, the mechanical effects are found to slow down above 100 kHz when the frequency increases. In case of the analysis of solution viscosity, since this method yields the same apparent results in both aqueous and benzene solutions, our study propose an alternative simple, cost effective method to quantify the mechanical effects in sonochemistry.