Studies on oil distribution in polymer blends

Oils and resins are widely used in rubber industries to improve or control the mechanical properties, viscoelastic behavior, processability, and tackiness of a rubber compound. Very few fundamental studies have been reported on the function and the mechanism of oils and resins in a rubber mixture. In this article oil or resin distribution to each phase in an immiscible binary elastomer blend was studied by measuring the change of thermodynamical parameters, such as glass transition temperature, melting point of crystallines, and heat at melt of each polymer component. Several independent approaches give consistent results. It was found that aromatic oil was favorably distributed to the polystyrene-butadiene (SBR) phase of an SBR/natural rubber (NR) blend. Similarly, unequal distribution of resin in a blend was observed for a natural resin (rosin) and a petroleum resin.