抄録
The testing apparatus was provided with a spring set tandem to the specimen of unplastic polyvinyl chloride so to be worked as to have constant strain at constant temperature, and in the process of recovering from the strain incurred during the reheating of the specimen we tried to separate the permanent strain from the elastic strain, which was produced by the spring force, and tried to obtain approximate value of the modulus of elasticity during the repeating process of the material. But in view of the fact that in our experiment it is very hard to measure the elastic strain directly and exactly, we determined to be content with approximate value of the modulus under the following assumption.
That the difference between the strain release under the spring load at three minutes of initiation of measurement and the strain release under no load, i. e. the strain as it stood at the time of three minutes of measurement, would constitute the total elastic strain by which the modulus of elasticity was to be calculated. Assuming that the value of modulus of elasticity is constant during the process of recovering from the strain, we calculated not only the elastic strain, but also the corresponding permanent strain.
The result of our experiment indicates the fact that the greater the spring constant is, the greater the value of suppressed permanent strain is at any repeating temperature.
