Polymer compatibility is an important factor in the processing of polymer blends. Compatibility is critical in governing the morphology of polymer blend and, therefore the final state physical and mechanical properties of the system. The major governing factor that control the compatibility in polymer blends are the rheological properties of the two-component material. The hydrodynamic properties of polymer mixtures were studied and a significant change of the slope of the reduced viscosity as a function of concentration was found polymer. Polymer blending is widely used as a cost effective way of producing new materials with customized properties. As polymer blends represent more than 30% of all plastics sold today and are amongst the most rapidly growing areas of polymer technology, there is a great challenge in designing and producing such materials by controlling their morphology, particularly during their processing. The structure of blend constituents and incorporated additives determines the final properties of the blend. Therefore, understanding the interplay of morphology, chemical structure and processing is essential.