INFLUENCE OF THE SOLVENT ON THE FREQUENCY DEPENDENCE OF THE ULTRASONIC ABSORPTION COEFFICIENT IN CONCENTRATED POLYMER SOLUTIONS.

被引：0

作者：

Borodin, V.N. ^{[1
]}

Grigor'ev, S.B. ^{[1
]}

Mikhailov, I.G. ^{[1
]}

机构：

[1] Leningrad, Leningrad, Russia

来源：

Soviet Physics, Acoustics (English translation of Akusticheskii Zhurnal) | 1975年 / 21卷 / 05期

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摘要：

The absorption coefficient for longitudinal ultrasonic waves in solutions of polystyrene and polymethylmethacrylate in a number of organic solvents is measured in the frequency range from 0. 15 to 1000 MHz. It is shown that the frequency dependence of the additional absorption DELTA alpha /f**2 has a complex form and depends strongly on the thermodynamic quality of the solvent. It is found that the spectrum of relaxation times becomes progressively narrower in the sequence of solvents methylethylketone-dioxane-toluene-n-xylene. It is hypothesized that the main factor contributing to the ultrasonic absorption at high frequencies is the bulk viscosity associated with rotational isomeric processes; a segmental friction mechanism begins to be operative at low frequencies.

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页码：425 / 429