对MDTA中测样品热容量的准恒温法的评述

Review on the Quasi_isothermal Heat Capacity Measurement in Modulated Differential Thermal Analysis

对用调制差热分析（ＭＤＴＡ）准恒温法测样品热容量的情形进行了讨论。通过结合最基本的热传导定律和ＭＤＴＡ模型，指出了目前国际上测量样品热容量的准恒温法只能得到在所测温度范围内的物质热容量平均值，调制温度的幅度越大或调制频率越高，所得到的热容量数据越平滑。在所测温度范围内样品热容量基本不变时，用ＭＤＴＡ准恒温法较好；但当样品热容量在所测温度范围内有明显变化时，用传统差热分析法（ＤＴＡ）更好一些。

The quasi_isothermal method used in modulated differential thermal analysis (MDTA) for heat capacity measurement is reviewed.With the aid of heat transfer law and the MDTA model,authors found that a heat capacity obtained by the quasi_isothermal method was actually an average value within measured temperature intervals.The higher the modulated amplitude and frequency,the smoother the heat capacity curve is.In case that the sample heat capacity remains approximately constant within the measured temperature range,the quasi_isothermal method is preferable.On the contrary,if the sample heat capacity apparently varies with temperature within the measured temperature range,the traditional DTA method for heat capacity measurement is recommended.