Polymer blending is a process of combining two different compatible or non-compatible polymeric materials, to achieve synergistic properties. Miscibility of a polymer blend containing two polymers depends on the mutual solubility of the polymeric components. For a blend to be compatible when the solubility parameters of the two components are nearer to each other and if the blends shows a single glass transition temperature. However, most polymers pairs tend to be immiscible due to differences in their viscoelastic properties, surface tension and intermolecular interactions and by the terminology, the polymers pairs are incompatible and show two glass transitions. In blending of immiscible polymers, optimum adhesion between the dispersed phase (domain) and the matrix are gainfully attained through the use of a third component known as reactive compatibilizer, having chemical structural features matching those of the component polymers. Polymer blends are prepared by mixing of polymers through latex mixing, solution mixing and melt mixing. Rubber blends based on Natural rubber-Styrene-butadiene rubber are compatible and widely used in tire industry applications.