Carbon Black Distribution in NR/Polybutadiene Blends

Abstract

Abstract The distribution of carbon black between the phases of a NR/cis-1,4-polybutatdiene (BR) blend was studied. An N550 carbon black was added to the blend using different mixing techniques. The carbon-black distribution was determined using a variety of analytical techniques. The crystallization temperature of the BR was measured by differential scanning calorimetry. This temperature is related to the carbon-black level in the BR phase. Samples were dissolved in toluene to separate the bound and soluble rubber portions and the fractions were analysed for polymer type and amount by solid stale 13C MAS nuclear magnetic resonance. Results indicated that the N550 black has no preference for either the NH or the BR. In phase mixed samples, the majority of the black remains in tho polymer to which it is initially udded. When black and polymers are mixed simultaneously, the black tends to distribute itself uniformly between the polymers. Physical test results on a typical sidewall compound indicated that the location of the carbon black has a significant effect on physical properties, especially cut-growth resistance.