MESOSCOPIC DESCRIPTION OF EPDM

O. A. LAMBRI; P. A. SORICHETTI; J. A. GARCÍA; R. R. MOCELLINI; G. I. ZELADA-LAMBRI; C. L. MATTEO; F. PLAZAOLA; A. RODRÍGUEZ-GARRAZA

Misiones

Congreso; XIII ERIAC DÉCIMO TERCER ENCUENTRO REGIONAL IBEROAMERICANO DE CIGRÉ; 2009

CIGRÉ

In the electrical industry, organic insulators with housings made of different kinds of rubber have been employed since more than 20 years in medium and high voltage transmission lines. However, the mechanisms of rubber deterioration are still unclear. In fact, the progressive deterioration can lead to the unexpected failure of the material. The knowledge of the physical processes which control the electrical and mechanical stability of polymers during in-service ageing is critical to predict accurately the life-time of polymeric insulators in HV transmission lines. This is particularly relevant for engineering modelling, planning and design purposes. It has been already reported that neutron irradiation on EPDM (ethylene-propylene-diene monomer) leads to the increase in the crystallinity degree through a process of chemi-crystallization, depending of the dose and neutron flux level. On the contrary, out-door ageing of EPDM under electric field, leads to a decrease in the crystallinity degree.In this work, experimental results are presented from dynamic mechanical analysis, positronannihilation spectroscopy and dielectric relaxation studies on neutron irradiated commercial EPDM. A mesoscopic description of the rubber as a function of the crystallinity degree is proposed.