Identification of Elastomers by Thermal Analysis

Abstract

Abstract Degradation of polymers by thermal and thermooxidative reactions is associated with either evolution or absorption of heat which can be followed by differential scanning calorimetry. In the present investigation, DSC thermographs of elastomers between 0° C and 500° C in nitrogen (thermal degradation) and oxygen (thermooxidative degradation) were used for identification of the elastomers from their degradation patterns. Based on the nature of the thermographs of the raw polymers in nitrogen, the elastomers studied may be divided into the following three main groups: (a) those which show an exotherm, (b) those which show an endotherm, and (c) those which show multiple peaks of endo- or exotherms. Identification is aided in some cases by the thermographs in oxygen as well as by the physical transitions. The nature (exo- or endo-) and shape of the thermal patterns and the temperature domain at which the reactions take place depend on the molecular structure, configuration, chemical composition, and nature of the substituents as well as on the environment. Consequently, thermal and thermooxidative degradation curves may be used as a “fingerprinting” device which can identify many polymers, difficult to identify by other methods.