Thermal analysis of high polymers: Differential thermal analysis and dynamic electrothermal analysis

Abstract The presentation consists of two parts. In the first part, a modification of a previously reported high‐resolution differential thermal analysis apparatus is described which extends the temperature range to 1100°C. and permits operation at pressures as low as 10μ. A sample of less than 1 mg. may be used to give well defined thermograms. The thermal behavior of an aromatic polyimide was studied and also of TFE‐fluorocarbon rosins in nitrogen and oxygen at various pressures. In the second part, an apparatus for performing simultaneous differential thermal analysis (DTA) and electrothermal analysis (ETA) is described. Changes in both heat content and electrical resistivity of a single sample are followed continuously as a function of sample temperature. Physical transitions such as melting, crystallization, glass transition, vaporization, and crystalline structural changes, and decomposition reactions are readily studied for a variety of polymer systems.