縦波による高分子溶液の緩和現象
1970 年 19 巻 199 号 p. 375-379
詳細
1970 年 19 巻 199 号 p. 375-379
The ultrasonic absorption of polymer solution was measured by the pulse method over 5Mc-45 Mc within the temperature range from -45°C to 30°C. Samples were prepared of polyvinylacetate, polymethylacrylate, and polyvinylchloride. Polyvinylacetate samples were mostly the subject of discussion in this paper. The solvents were 1, 2-dichloroethane, cyclohexanone, toluene, acetone, and methanol. The concentration of solution was from 1g/100c.c. to 7g/100c.c.,
From the curve which was plotted of absorption coefficient divided by square of frequency (This quantity is represented by α/f2, where α is absorption coefficient and f is frequency.) against the logarithm frequency, the relaxation phenomena were observed in all the solutions. When α/f2 was plotted against temperature, this curve exhibited a maximum in various P.V. Ac. solution. The position of this peak does not depend on the concentration. But the peak of the curve shifts toward the higher temperature at higher frequency. It is thought that the relaxation means thermal relaxation. Then temperature-frequency superposition is to be discussed. Shift factor at was determined by the usual method. The curve of shift factor versus temperature was compared with W.L.F. equation. The result of the experiment is in good agreement with the theory.
Next, the concentration dependence of α/f2 was discussed. Using the assumption of additivity of α/f2 between solvent and solute, the quantity α2/f2 (Apparent ultrasonic absorption of polymer) was calculated from the slope of the curve of α/f2 versus concentration. From the results, it is concluded that α2/f2 is independent of solvent within the error of experiment.
Finally, the assumption of single relaxation was discussed as was made in the conclusion by Bauer et al. and Miyahara et al. in the polystyrene solution. The relaxation frequency, used in the assumption of single relaxation theory, was determined by the I.B.M.-1620 computor. The temperature dependence of hypothetical relaxation frequency was divided into two parts of P.V. Ac. solution. One part was like a single relaxation (0°C-20°C). The other part did not depend on temperature (-40°C-0°C). It is considered that the relaxation observed in P.V. Ac. solution was multi-relaxation.
