高分子物質の弾性率の温度変化に現われる特異点について
1958 年 27 巻 5 号 p. 281-285
詳細
1958 年 27 巻 5 号 p. 281-285
Variation of extensional creep compliance (or its reciprocal) of polymethylmethacrylate and
polystyrene with temperature is measured in their glasslike consistency by observing bendingcreep of beam-shaped specimens in the time range from 15 sec to 15min.
In compliance-temperature diagram of each of the two polymers a characteristic break point is found, which is independent of creep time and coincides with those found in ultrasonic velocity-temperature diagram and in specific volume-temperature diagram and in specific volume-temperature diagram.
The ratio of temperature coefficients of compliance, taken just above and just below the break point, agrees with that obtained from volume expansion measurement.
It is, therefore, verified that the break point is completely independent of mechanical time-scale and that it is dominantly governed by an abrupt change in the density.
In the case of polystyrene, another characteristic temperature, lower than the above-mentioned one, is found, below which relaxation effect is markedly depressed.
The static experiment as employed in the present case could be used as a simple and direct method to explore the characteristic temperatures of high polymers which are defined as the break points in specfic volume-temperature diagram.
