Hypothesis: After gelation, the viscosity of the hydrogel can be reduced under ultrasound at room temperature. Changes in temperature, composition and solvent ratio (water/ethanol) affect cavitation and therefore reactions under
ultrasound by changing the vapor pressure and viscosity, and both play a fundamental role in the cavitation capacity of the solvent. In this paper, the effect of environmental factors on the degradation rate of one of the important commercial hydrogels containing acrylic acid and acrylamide was studied.
Methods: Viscosity measurement method was used to study the degradation behavior of hydrogel and a first-order kinetic equation was developed to calculate the corresponding rate constants. The degradation reaction was carried out in a steel cylinder containing 12 mL of hydrogel sample in distilled water. The environmental parameters studied included temperature, concentration, pH, volume, solvent, H₂O₂ NaCl and probe tip distance and their effect on the degradation and decomposition rate of hydrogel is certain. The role of these factors is mainly through changes in vapor pressure, viscosity and active volume of the reaction. An ultrasonic probe with a fixed frequency, power and pulse (20 kHz, 85% (60 W) and 8) was used in all cases
Findings: The results showed that the amount of viscosity loss is directly related to concentration and inversely related to temperature and sample volume. Also, an optimal depth is needed to have the greatest sonochemical effects. This effect is initially high. We found that shear forces resulting from rapid solvent movement due to cavitation collapse control the degradation of polymer chains. Spectroscopic results confirm the breakage of carbon-nitrogen single bonds by mechanical forces. This work can investigate the role of various environmental factors in ultrasonic degradation and the amount of viscosity loss of hydrogel.