Preparation and properties of styrene-butadiene rubber/clay nanocomposites by using liquid rubber/clay master batches

Rubber/clay nanocomposites (RCNs) have many applications because of their improved properties. The dispersion of clay in a rubber matrix, which plays an important role in the properties of RCNs, is a challenge. In this article, a solvent-free approach to produce the styrene butadiene rubber (SBR)/clay nanocomposites by using liquid rubber/clay master batches was introduced. The liquid/rubber master batches were first prepared using a high-speed centrifugal mixer and then compounded with neat SBR using conventional rubber compounding equipment. Compared with the composites prepared by melt mixing, this approach resulted in a better dispersion of the clay in the rubber matrix and improvements in tensile strength (4.98 MPa at 10 phr clay loading) and elongation at break (>1000% at 10 phr clay loading). The improved dispersion was confirmed by X-ray diffraction. The effect of clay loading on the tensile properties, dynamic mechanical properties, and the Payne effect was also investigated. The increase in clay loading resulted in a steady increase in the tensile properties up to a loading of 15 phr. The reinforcement in the RCN modulus using clay was compared with five models, including the Guth and Halpin-Tsai equations. This solvent-free approach offers benefits in dispersion of clay for industrial applications of rubber nanocomposites.