Investigation of accelerated thermal aging of EPDM polymer by electric tests in air and by means of a SEM technique in high vacuum

In the current work we will concentrate on the study of thermal accelerated ageing process. A specific example focuses on the degradation of Ethylene Propylene Diene Monomer (EPDM). The reference material and the aged specimens were characterized by electrical methods performed in air and by a method developed in vacuum of a scanning electron microscope (SEM). A temperature of 90° C in air is considered for aging. Maximum exposition times were 6600 h in hot air. Physical properties such as transverse resistivity and permittivity are monitored, as well as charging ability under electron irradiation. A qualitative interpretation of the results is given. This interpretation is based on the enhancement of the disorder in the aged material which resulted in higher density of localized surface defects in the band gap.