| 摘要 |
PROBLEM TO BE SOLVED: To evaluate unevenness of a synthetic resin by applying a strain vibration of a plurality of frequencies at the vicinity of a glass transition temperature, and calculating a shift factor at each temperature from a generating displacement. SOLUTION: A sample 1 is fixed between sample chucks 32a and 32b, and held in a constant temperature tank 2. A vibration is applied to the tank, and its displacement is detected by a displacement sensor of a displacement detector 4. A displacement signal from the sensor and a load signal from a load sensor are converted into digital signals by an analog-digital converter 61, and then stored in a memory 62. Measured data at the respective temperatures are read by an arithmetic unit 63, which obtains a difference between a displacement phase and a load phase and/or a ratio of a load magnitude to a displacement width, and calculates a shift factor aT by formulae I and II. Then, these values are used, and a change rate of Tg/T of log aT at a glass transition temperature Tg is obtained. Thus, unevenness of the synthetic resin can be easily evaluated without measuring a viscosity change rate, and a fracture toughness value can be estimated from this.
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