Sakatsuji Waki, Konishi Takashi, Miyamoto Yoshihisa
Division of Physics and Astronomy, Graduate School of Science, Kyoto University, Kyoto, Japan.
Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan.
Phys Rev E. 2016 Dec;94(6-1):062501. doi: 10.1103/PhysRevE.94.062501. Epub 2016 Dec 5.
The origin of two maxima in specific heat observed at the higher and the lower temperatures in the glass-transition region in the heating process has been studied for polymethyl methacrylate and polyvinyl chloride using differential scanning calorimetry, and the calculation was done using the phenomenological model equation under a thermal history of the typical annealing experiment composed of cooling, annealing, and heating. The higher maximum is observed above the glass-transition temperature, and it remains almost unchanged independent of annealing time t_{a}, while the lower one is observed above an annealing temperature T_{a} and shifts toward the higher one, increasing its magnitude with t_{a}. The analysis by the phenomenological model equation proposed in order to interpret the memory effect in the glassy state clarifies that under a typical annealing history, two maxima in specific heat essentially appear. The shift of the lower maximum toward higher temperatures from above T_{a} is caused by an increase in the amount of relaxation during annealing with t_{a}. The annealing temperature and the amount of relaxation during annealing play a major role in the determination of the number of maxima in the specific heat.
利用差示扫描量热法研究了聚甲基丙烯酸甲酯和聚氯乙烯在加热过程中玻璃化转变区域较高温度和较低温度下比热出现两个最大值的起源，并使用现象学模型方程在由冷却、退火和加热组成的典型退火实验的热历史下进行了计算。较高的最大值出现在玻璃化转变温度以上，并且几乎不随退火时间(t_{a})变化，而较低的最大值出现在退火温度(T_{a})以上，并向较高的最大值移动，其幅度随(t_{a})增加。为解释玻璃态中的记忆效应而提出的现象学模型方程分析表明，在典型的退火历史下，比热中本质上会出现两个最大值。较低最大值从(T_{a})以上向较高温度的移动是由于退火过程中随着(t_{a})松弛量的增加。退火温度和退火过程中的松弛量在比热最大值数量的确定中起主要作用。
