THERMAL AND ELECTRICAL STUDIES ON IRRADIATED SILICA-ETHYLENE-PROPYLENE DIENE MONOMER (SIO2 EPDM) COMPOSITES/

Ethylene propylene diene monomer (EPDM) was mixed with a concentration of (40 phr) of three types of silica (SiO2) with different surface ar eas. The obtained vulcanizates were subjected to thermal properties me asurements (thermal conductivity, lambda, thermal diffusivity, a, and specific heat capacity, C-p using the flash method technique in the te mperature range (30-150 degrees C). The addition of polar SiO2 was fou nd to increase the thermal diffusivity, whilst it decreases upon the a ddition of non-polar SiO2. Radiation sensitizer was found to decrease the value of the specific heat for all composites. The addition of EGD M as coagent increases the value of lambda for EPDM containing non-pol ar SiO2. Degradation is found to be the predominant process for all EP DM loaded samples at gamma-irradiation dose greater than or equal to 1 5 kGy. Moreover, the effective thermal conductivity was calculated usi ng a simple model. The addition of EGDM as coagent increases the value of the dielectric constant (epsilon') for EPDM containing non-point S iO2 (type A-972) whilst, it decreases epsilon' for the other white fil lers. (C) 1998 Elsevier Science Ltd All rights reserved.