Ethylene-propylene-diene (EPDM) rubber/borax composite: kinetic thermal studies

This research studies the effect of borax on the thermal stability and thermal kinetic behavior of ethylene-propylene-diene (EPDM) rubber composites. Using a laboratory two-roll mill at room temperature, carbon-black (N-220) as filler, and other additives such as zinc oxide, stearic acid, and paraffin oil were incorporated into the EPDM rubber matrix. The composite was prepared at different borax concentrations (25 and 50 phr). Thermogravimetric analysis was performed to characterize borax's effect onthermal stability before and after borax addition. Added borax to the host composite rubber (EPDM composite without borax) significantly improved the composite's thermal stability. Borax-loaded composites behave differently at various temperatures. To investigate the kinetic-thermal analysis of the prepared samples, three different models were applied. The activation energy (Ea) and frequency factors (A) for the Horowitz-Metzger, Broido and Coats-Redfern models were calculated. These models were compared and discussed based on their results. First-order decomposition also represented the main decomposition stage. Kraus and Cunnen-Russel models were used to test the interaction between rubber and borax based on previously published swelling results. No interaction was found between rubber and borax.