The Ultrasonic Velocity and Absorption of Aqueous Solutions of Polyvinyl Alcohol

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Abstract
An ultrasonic pulse technique has been applied to measure the velocity and absorption of the longitudinal sound wave in aqueous solutions of polyvinyl alcohol at ultrasonic frequencies. Two samples of polyvinyl alcohol have been used: sample A, completely saponified polyvinyl alcohol, and, sample B, partially saponified Polyvinyl alcohol (including residual acetate groups by 12.2 mol.%). The following results have been obtained. 1) Ultrasonic velocity and absorption have been measured over the temperature range of 3∼70°C in the concentration range of 5∼15% by weight. 2) For sample A the temperature dependence of velocity is similar to that for pure water, but for sample B the velocity vs. temperature curves have been found to have a broader peak. 3) Concerning the concentration dependence of the velocity, in sample A the sound velocity increases with the increase in the concentration, but in sample B a reverse dependence of velocity on concentration has been found at higher temperatures. 4) The value of M2/ω amounts to about 2∼3 poises on the average for both samples. 5) The compressibility of polymer molecules in solutions has been calculated to be 26.5×10−12 c.g.s.u. on the average for completely saponified polyvinyl alcohol.

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