Abstract

Fatigue properties of rubber are one of the most important characteristics in the rubber industry. In this study, the fatigue properties of MREs (magneto-rheological elastomers) based on NR (natural rubber), EPDM (ethylene-propylene diene monomer), and AEM (ethylene/acrylic elastomer) were investigated. For comparison, MREs with a Shore hardness of 60A were prepared. According to the relative results, the fatigue properties of EPDM MRE were the worst. Thus, we investigated methods to improve the fatigue properties of EPDM MRE by varying the carbon black content and curing systems of EPDM as the matrix of the MRE. Dynamic properties were measured using a fatigue tester and an RPA (rubber process analyzer), and the XPS (X-ray photoelectron spectroscopy) was used to analyze the curing system of the EPDM matrix. According to the results, the Payne effect increased and the fatigue resistance decreased as the carbon black content in-creased. In case of the curing system, the CV (conventional vulcanization) system was superior to the EV (efficient vulcanization) system in terms of the fatigue resistance. This was because the number of flexible bonds in the case of the CV system was higher than that in the case of the EV system. However, the EV system showed excellent mechanical properties because it had many monosulfidic bonds with strong binding energy.

Keywords: EPDM;MRE;fatigue resistance;curing system;payne effect