The Role of Heat Transfer and Analysis Ensuing Heat Inertia in Thermal Measurements and Its Impact to Nonisothermal Kinetics

Abstract

The basic interrelations and consequences of heat transfer (1701 Newton cooling law) are analyzed showing its unambiguous importance and historical origin already known since 1933 in the form of basic caloric equation by Tian. It results in the heat inertia due to the sample heat capacity changes and undertakes two forms, integral and differential, the latter specific in providing s-shape background of DTA peaks. Its impact in the DTA measurements is examined showing misinterpretation by the origin work of Borchard and Daniels leading to further abandonment. The heat inertia correction was already suggested by authors in 1978 and verified on the basis of externally inserted rectangular heat pulses. Further corrections to heat inertia waited until 2009 (Netzsch commercial software). Relations following from general kinetic equation for the first-order reactions are substantiated, and the kinetic compensation effect explained as a correlation of pair activation energy pre-exponential factor and maximum rate temperature-heating rate. Kissinger erroneous assumption on temperature of maximum reaction rate is examined, and a correct solution is then suggested while determining the correct temperature of maximum reaction/transition rate and its correlation to the apex of a DTA peak. Both the kinetic equation and Kissinger equation are shown crucial when including the heat inertia term. Often forgotten influence of thermodynamic equilibrium as to kinetic equation is analyzed giving away its significance. New concept of a more sophisticated nonisothermal kinetics is suggested happy to be first when introducing the concept of equilibrium background which stays an important part of advanced kinetics anticipating that our innovative notions of temperature inertia, gradients, and even the operational meaning of temperature itself may facilitate modern kinetic understanding. We believe that kinetic progress means practice-verified improvements while including detailed thermal phenomena of real thermoanalytical measurements, nor just making changes at any case. We neither should be afraid of changes while complicating our pervious practice nor should we feel troubled examining examples presented in this chapter. The chapter contains 72 references.