Abstract
In our previous paper, it was reported that the covulcanization of EPDM with NR was much improved by addition reaction of sulfur compounds to EPDM under heating before blending it with NR. In this paper, the covulcanization was discussed by measuring hysteresis loss, strain energy and constant stress fatigue life. Practical application to the side-wall of bicycle tire was evaluated.
It was found that vulcanizate of P-EPDM (EPDM with pendent sulfur) with NR showed good covulcanization behavior. But the blend of EPDM with NR did not covulcanize satisfactorily and EPDM portion worked as flaws in constant stress fatigue life test. Mechanical crack was observed on the tire of EPDM-NR blend in the early stage of field test, but no crack on one of P-EPDM-NR blend even after 2-year field test.
