Temperature Dependence of Velocity and Attenuation of Ultrasonic Waves in High Polymers

概要

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Measurements of velocity and attenuation of ultrasonic waves are carried out for polystyrene, polymethyl methacrylate, phenol resin, polyethylene, nylon 6 and other commercial resins in the temperature from -60℃ to 90℃ and at frequencies of 100kc, 1.46Mc, 4.38Mc and 7.30Mc. A correlation between sound velocity in the megacycle range and density is pointed out for glassy polymers. In the case of linear polymers, the temperature coefficient of ultrasonic velocity, β, exhibits a relatively abrupt change in the glass trasition region at the temperature T_m, which is independent of frequency of sound agrees with the transition point associated with thermal expansion. The ratio of β to volume expansion coefficient a is found to be constant below and above T_m for each polymer. These facts indicate that the change in β at T_m should be ascribed to the temperature dependence of intermolecular free volume. For some polymers a change in β and a peak of loss factor are observed at lower temperatures.
社団法人日本物理学会の論文
1956-08-05