Influence of benzyl esters of vegetable oils on curing, mechanical and dynamic properties of silica filled natural rubber and styrene-butadiene rubber compounds

Abstract

Benzyl ester oils (BEO) were prepared by esterification of fatty acids from three different types of vegetable oils, i.e., coconut, palm, and soybean oils using benzyl alcohol in the presence of an acid catalyst. They are then exploited as alternative rubber processing oils with the main aim to replace conventional aromatic oil. The influence of BEO on mixing, curing, viscosity, crosslink density, dynamic and mechanical properties is investigated in silica-filled natural rubber (NR) and styrene butadiene rubber (SBR) compounds. The rubber compounds with BEO exhibit lower mixing energy, higher cure rate index (CRI) and torque difference. Furthermore, the NR compounds with BEO have a lower Mooney viscosity than the one with aromatic oil, but the SBR compound has the opposed trend. Higher crosslink density and superior mechanical properties are observed in NR vulcanizates with the coconut benzyl ester oil. On the other hand, lower crosslink density and inferior mechanical properties are observed in the SBR vulcanizates with BEO as compared to the SBR compound with aromatic oil. It is therefore concluded that some types of the BEO could be possible as alternatives to be used instead of the typical aromatic oil in rubber compounds with some advantages.

Keywords

• rubber
• benzyl ester oil
• aromatic oil
• silica