1972 年 21 巻 224 号 p. 476-479
The ultrasonic absorption in solution of polyvinyl acetate in toluene was measured in the frequency range from 1 to 60MHz. The temperature range was from -20°to 60°C, and the concentration of the solutions was 5.42g/100ml. The degree of polymerization of the sample of polyvinyl acetate was 900.
The plot of Δ(α/f2) against frequency was represented by a single relaxation curve over the whole temperature range. With the rising temperature, the relaxation frequency fr increased and the absorption maximum per wavelength μmax decreased.
The energy difference ΔH0 and the activation energy ΔH21 were estimated from the change of temperature of the absorption on the basis of two-state model. The values obtained were: ΔH0=1.36kcal/mol, and ΔH21=1.0kcal/mot.