Comparative Properties of Vegetable Oil-Based Benzyl Esters and Vegetable Oils as Processing Oil in Natural Rubber Compounds

The vegetable oil tends to be incompatible and insoluble in the rubber hydrocarbon. They can migrate to the surface of the uncured rubber. To overcome this problem, fatty acid esters that are soluble in rubber material and minimize migration were prepared. Benzyl esters of three different types of vegetable oils (i.e., coconut, palm, and soybean oils) were prepared by reacting fatty acids of vegetable oil with benzyl alcohol. They were then used as processing oil in rubber compounding and processing compared with the one with unmodified vegetable oils. It was found that the benzyl esters of those oils provided the rubber compounds and rubber vulcanizates with superior Mooney viscosity, curing and mechanical properties. Furthermore, better dispersion of filler was observed compared with the rubber compound and vulcanizate with vegetable oil.