A New Method of Quantitative Differential Thermal Analysis

Abstract

This paper presents a rigorous new theory of differential thermal analysis, taking account of the temperature gradient in the sample. From this consideration, a new quantitative method is proposed, where a solid-cell holder of low thermal conductivity is set between a sample cell and a metal block, and a thermocouple is inserted tightly between the outside wall of the cell and the cell holder. By means of this arrangement, the peak area becomes proportional to the heat of transformation, irrespective of the kinds and the states of samples and operational variables. The experimental verification using various samples and the effect of several operational variables, such as the heating rate, the concentration of a diluent, the packing density, and the depth of the packing sample, are also shown; satisfactory results are obtained. Two new concepts, the sensitivity and the response time of the system, are proposed and evaluated. Conventional methods are criticized, and the inherent limitations of differential thermal analysis are discussed.