Physical properties and failure behaviors of NR/BR blend compounds

Various physical properties including failure properties were investigated for carbon black-filled NR/BR (natural rubber/polybutadiene rubber) blends in terms of blend ratio. To see the effect of carbon black type, two different carbon blacks were also incorporated in the rubber blends. In the range of BR content below 40 phr (NR-rich range), the effect of BR content on the tensile strength and tack property of the green compounds was relatively small, but a considerable effect was observed in the range above 40 phr. Apparent cure rate of NR was higher than that of BR, NR vulcanizate was found to be much stronger than BR one in view of tensile strength, crack resistance, and fatigue resistance, however, it was rather inferior in view of abrasion resistance, cutting-chipping resistance, and resistance to heat. 26 refs., 13 figs., 1 tab.