Thermal and electrical behaviour of radiation vulcanized EPDM/Al2O3 composites

Thermal degradation as well as the thermal and electrical properties has be en explored for gamma-radiation-vulcanized EPDM rubber/Al2O3 composites. Va rious particle size namely, 0.02, 0.3 and 1.0 mu m of 40 phr of Al2O3, were considered. The effect of adding EGDM as radiation sensitizer to the syste m has been also investigated. Thermogravimetry (TG) and derivative thermogr avirnetry (DTG) have been applied to study the thermal degradation at tempe ratures ranging from 25 to 800 degrees C. The effect of temperature in the range of 25-150 degrees C on the thermal and electrical properties of these composites has been also studied. The addition of Al2O3 leads to increase in the values of thermal diffusivity coefficient and the dielectric constan t and decrease in the values of the specific heat for composites in the pre sence or the absence of the radiation sensitizer. The thermal and electrica l properties of the composites depend on the particle size of the incorpora ted filler beside the irradiation dose of vulcanization. Moreover, these pr operties are slightly changed with temperature. The addition of EGDM decrea sed the dielectric constant of EGDM containing Al2O3 fillers. Degradation i s predominant for all samples at radiation doses greater than or equal to 1 50 kGy. (C) 1998 Elsevier Science Limited. All rights reserved.