Detection and Analysis of Critical Characteristic Temperatures of the Reaction Process

The critical characteristic temperatures, i.e. onset temperature and end temperature of chemical reactions, are hard to determine. Instead, the extrapolated ones by the tangent method are commonly used. However, problems such as large errors and uncertainty of the tangent method are restricting its application. In this paper, the noise power window function (nPWF (R)) method was firstly proposed and applied to determine the critical temperatures. The construction theory of nPWF (R) method and analysis process were comprehensively introduced. Three typical reaction processes including decomposition of calcium carbonate (CaCO3), melting/solidification of tin (Sn) and carbon gasification were conducted under controlled temperature programmes. The detection signals of DTG (derivative thermogravimetric analysis), DTA (differential thermal analysis) and gas component yield were interpreted to the nPWF signal to determine the critical temperatures, with a high accuracy improved by 1-2 orders of magnitude than the extrapolated ones. Finally, accuracy, applicability and superiority of the nPWF (R) method were analysed.