In the enthalpy relaxation of poly(vinyl chloride), a decrease in enthalpy upon the isothermal ageing was measured using the differential scanning calorimetry method as a function of ageing time (t_A) and ageing temperature. The range of the ageing temperature was from 56 °C (T_g − 25 °C) to 72 °C (T_g − 9 °C) where T_g denotes the glass transition temperature. The limiting value of the decrease in enthalpy was determined by applying a stretched exponential function to the measured enthalpy data. The relaxation function (ϕ) was derived from the measured enthalpy and the construction of a master curve was tried by shifting the ϕ − t_A curves of the respective ageing temperatures horizontally. Although there was no agreement between the shift factors (a_T) and the relaxation times of the ϕ − t_A curves, the superposition was successfully constructed and the a_T values obtained for the poly(vinyl chloride) sample were found to be comparable to those reported for viscoelastic experiments over a broad temperature range above and below T_g carried out for different polymers. The origin of the decrease in enthalpy was briefly discussed in terms of the chain dynamics in the isothermal condition.

在聚氯乙烯的焓弛豫中，使用差示扫描量热法测量了等温老化后焓的降低，它是老化时间（t _A）和老化温度的函数。时效温度范围为56°C（T _g − 25°C）至72°C（T _g − 9°C），其中T _g表示玻璃化转变温度。通过将拉伸的指数函数应用于所测量的焓数据来确定焓降低的极限值。弛豫函数（ϕ）是从测得的焓导出的，通过移动ϕ- t _A来尝试构建主曲线时效温度的水平曲线。尽管位移因子（a _T）和ϕ- t _A曲线的弛豫时间之间没有一致性，但成功构建了叠加，并且发现聚氯乙烯样品的a _T值与对于不同的聚合物，在高于和低于T _g的较宽温度范围内进行粘弹性实验报道的那些。根据等温条件下的链动力学简要讨论了焓降低的根源。