Chapter 8 Controlled Rate Thermal Analysis and Related Techniques

Abstract

Most thermal methods are based on subjecting a sample to a predetermined temperature program, almost always either isothermal or linear, while measuring one or more of its properties. The temperature program proceeds in the manner chosen by the experimenter regardless of any changes undergone by the sample. There are methods that have departed from this approach by allowing the measured sample response to influence the course of the temperature program in some way. Several algorithms have been used to determine the changes in the temperature program as a function of sample behavior and a variety of different sample properties have been used as the input to the temperature controller. This has given rise to a number of different methods that are the subject of this chapter. This chapter focuses on the controlled rate thermal analysis and related techniques. There are a growing number of techniques where the temperature to which the sample is subjected is influenced in some way by the measured sample response. The earliest examples of this approach sought to keep the rate of any transformation that the sample undergoes at a constant or near constant rate. The advantages include improvements of resolution, better kinetic data, and better control when preparing porous material by decomposition. Later approaches were more flexible and complex algorithms that can be used mainly to improve resolution. It is encouraging that these techniques are becoming commercially available, and there are more examples of these approaches being applied to a wider variety of thermal methods.