Carbon black reinforced natural rubber/butadiene rubber and natural rubber/butadiene rubber/styrene-butadiene rubber composites: Part II. Dynamic mechanical properties and fatigue behavior

Carbon black reinforced natural rubber (NR)/butadiene rubber (BR), NR/styrene-butadiene rubber (SBR) and NR/BR/SBR composites were prepared by using two types of BR with highly linear chain structure (higher viscosity and molecular weight) and branched chain structure (lower viscosity and molecular weight). NR/BR composite consisting of BR with higher viscosity has the highest fatigue strength. Damping factors of NR, NR/SBR and NR/BR/SBR composites as a function of frequency were systematically compared at constant temperatures of -40, 0, 25 and 60°C. Based on dynamic mechanical analysis (DMA) results, the elasticity of NR/carbon black composite improves, its heat buildup character and tan d decreases with the addition of BR. The addition of 20 phr BR to NR/SBR composites provides 4-5 times better fatigue strength due to the decrease of tan d. Lastly, using a higher viscosity BR in carbon black filled NR or NR/SBR is quite favorable in terms of using these composites as anti-vibrational rubber bushings in automotive applications where high fatigue resistance and lower damping factor are important criteria.