The influence of modified soybean oil as processing aids in tire application

Rubber process oils (RPOs) are generally incorporated to rubber compounds for improving processability and also state-of-mix in some circumstances, for example; in the formulations having relatively high filler content. The aim of this work is to prepare the modified soybean oil (MSO) via transesterification reaction of soybean oil (SO) with benzyl alcohol. The success of modification was evidenced by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy (NMR). After modification, the new absorption peaks at 3020 cm⁻¹ and 750 cm⁻¹ corresponding to –CH stretching vibration and C–H out-of-plane of aromatic were observed. ¹H-NMR result also shows the signal of proton in aromatic ring at 7.40–7.55 ppm confirming the presence of aromatic ring in SO. The prepared MSO was then used as rubber processing oil (RPO) in tread compound formulation, and its performance was compared with unmodified SO, distillate aromatic extract oil (DAE) and treated distillate aromatic extract oil (TDAE). The incorporation of RPOs demonstrated cure retardation with a minimal magnitude found in the MSO-filled system. However, the addition of RPOs decreased the mechanical properties, i.e., hardness, modulus, tensile strength and tear strength. Among the studied RPOs, SO showed the poorest performance in terms of rubber mechanical properties, whereas MSO gave the rubber vulcanizate with comparable mechanical properties to DAE and TDAE. Similar to DAE and TDAE, the addition of MSO resulted in the improved wet grip with the sacrifice of rolling resistance.