Thermal analysis of dielectric insulation,ethylene/propylene rubbers,and cross-linked polyethylenes decomposed in a nitrogen atmosphere

The techniques of thermogravimetric and derivative thermogravimetric analyses have been applied to the determination of temperatures and heats of decompositions of four ethylene/propylene rubbers and seven cross-linked polyethylenes in nitrogen. These materials are commonly used in the wire and ruble industry as dielectric insulation. The polymers were found to decompose in at least three overlapping stages. Each stage has an activation energy characteristic of the process. Differential thermal analysis was significantly less useful in this study due to the conflict of the endothermal heat of vaporization and the exothermal heat of decomposition.