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. L. RODRÍGUEZ-GARRAZA

Parque Nacional Iguazú

Congreso; Décimo Tercer Encuentro Regional Iberoamericano del CIGRE (Consejo Internacional de Grandes Redes Eléctricas), XIII ERIAC 2009; 2009

Consejo Internacional de Grandes Redes Eléctricas

In the electrical industry, organic insulators with housings made of different kinds of rubberhave been employed since more than 20 years in medium and high voltage transmission lines. However, themechanisms of rubber deterioration are still unclear. In fact, the progressive deterioration can lead to theunexpected failure of the material.The knowledge of the physical processes which control the electrical and mechanical stability ofpolymers during in-service ageing is critical to predict accurately the life-time of polymeric insulators in HVtransmission 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 thedose and neutron flux level. On the contrary, out-door ageing of EPDM under electric field, leads to adecrease 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. Amesoscopic description of the rubber as a function of the crystallinity degree is proposed