Study of dielectric strength in EPDM by nondestructive dynamic mechanical analysis in high electrical field

SALVATORI, P. E.; PLAZAOLA, F.; GARGICEVICH, D.; BONIFACICH, F. G.; SÁNCHEZ F. A.; BOSCHETTI, C. E.; MOCELLINI, R.R.; GARCÍA, J.A.; GIORDANO, E. D.; LAMBRI, O. A.; SÁNCHEZ F. A.; SALVATORI, P. E.; MOCELLINI, R.R.; PLAZAOLA, F.; GIORDANO, E. D.; GARGICEVICH, D.; BOSCHETTI, C. E.; BONIFACICH, F. G.; GARCÍA, J.A.; LAMBRI, O. A.

IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Año: 2017 vol. 24 p. 1840 - 1851

1070-9878

In thepresent work the value of the degree of the area swept by the polymer chain dueto an electrical force for a given mesostructure was related to thecorresponding value of the dielectric strength. This value was deduced from theelectric inclusion formalism applied to dynamic mechanical analysis (DMA)studies conducted under high electric field, which were performed in commercialethylene-propylene-diene M-class rubber (EPDM); used for the housing ofpolymeric electrical insulators. EPDM samples with different arrangements ofthe polymer chains and crystalline degree, promoted by controlled neutronirradiation were studied. Several characterization techniques, as infraredabsorption spectroscopy (IR), differential scanning calorimetry (DSC), positronannihilation lifetime spectroscopy (PALS) and dielectric strength (DS) werealso used. The relationship between the DS and the degree of movement ofpolymer chains promoted by electrical forces coming from the electric fieldapplied in a non destructive test as the DMA was successfully established. Infact, a larger empty space in the sample leads to larger areas swept by thepolymer chains during bending under the application of the field strength inthe dynamic mechanical analysis tests. Therefore, an increase in the capabilityof movement of charges occurs, corresponding to smaller dielectric strengthvalues. Crystallinity improves the dielectric strength due to the increase inthe internal stresses which decreases the capability of movement of the polymerchains and electric carriers by electric forces