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Abstract
The effect of ultrasound (US) on the shear viscosity of water-soluble polymers, polyvinyl alcohol, polyethylene glycol and polyacrylic acid, was studied in aqueous solutions with US exposure of 23, 43, 96 and 141 kHz for an 8.5-9 W US. The US exposure significantly decreased the shear viscosity of the solutions in this order: 43>23>96>141 kHz. When US exposure was stopped, the shear viscosities of the aqueous polymer solutions reverted to their original values. US stimulation during the decrease in viscosity was supported by the ultrasonic power transmitted through the aqueous polymer solution. In addition, Fourier-transform infrared spectra obtained during US exposure showed that hydrogen bonds in the aqueous polymer solution could be broken, especially at 43 kHz. We concluded that US exposure influenced hydrogen-bond interactions between the OH groups of the polymer and water molecules in the aqueous medium. This finding was supported by US absorption of the aqueous polymer solution in the transmittance model, which shows the US absorptivity, [varepsilon]US , for each polymer system.