Abstract
To investigate generation of ultrasonic cavitation in gel, sodium polyacrylate swollen in potassium
iodide solution was used as a sample. After ultrasonic irradiation at 500 kHz, absorbance and viscosity of
sample were measured. The absorbance and viscosity changes are originated from oxidation reaction of
potassium iodide and decrease in the degree of polymerization of sodium polyacrylate, respectively. The
absorbance started to increase after several minutes irradiation. On the other hand, viscosity decreases
immediately after irradiation. This is because polymer is degraded due to shear stress of ultrasonic propagation
in addition to cavitation. After sample viscosity fully decreased, it is able to generate ultrasonic cavitation and
chemical reaction occurs. As sample temperature became lower, the viscosity decreased and the absorbance
increased. To use this sample, detection of cavitation generation in gel is possible.
