Mechanical property behavior and aging mechanism of carbon-black-filled EPDM rubber reinforced by carbon nano-tubes subjected to electro-chemical and thermal degradation

Ethylene propylene diene monomer (EPDM) rubber filled with Carbon black (CB) has been mainly used for the rubber hose of a cooling radiator in the internal combustion engine system. Moreover, EPDM aging occurs because of electro-chemical and thermal stresses. In this study, Carbon nanotubes (CNTs) with 0, 2 and 4 parts per hundred grams of rubber (phr) were added to EPDM rubber filled with 75 phr CB to form CNT reinforced CB-filled EPDM rubber. Under conditions of 3 temperatures (60, 80 and 100 degrees C) and constant voltage (DC 12 V), 3 types of EPDM rubber (CB75, C2CB7 and C4CB75) were immersed in coolant water and aged for 7 days (168 h). This study investigated the effects of CB and CNT concentrations in EPDM rubbers on electro-chemical and thermal degradation behaviors and mechanical properties (tensile strength, elongation at the breaking point and IRHD hardness). A conductive mechanism was also proposed for the addition of CNT and CB.