Fatty acid benzyl esters as bio-based plasticizers in silica-filled solution-polymerized styrene-butadiene rubber/butadiene rubber composites

Bio-oil based plasticizers have gained great attention in rubber industry as alternatives of petro-based plasticizers with high content of polycyclic aromatic hydrocarbons. In this work, five fatty acid benzyl esters were synthesized by the esterification of fatty acids (lauric acid, myristic acid, palmitic acid, stearic acid, and oleic acid, which are obtained after hydrolysis of some vegetable oils) with benzyl alcohol. They were further applied as plasticizers in silica-filled solution-polymerized styrene-butadiene rubber/butadiene rubber (SSBR/BR) composites in order to study the structure-property relationship, compared with treated distillate aromatic extract (TDAE) as standard. The composites were studied for their processability, curing, static, and dynamic mechanical properties by developing through compatibility between bio-plasticizers and polymer matrix. The results show that benzyl laurate with suitable hydrocarbon chain length and benzyl oleate with a carbon-carbon double bond have comparatively improved performance compared to TDAE in the silica-filled SSBR/BR composites.