Soy-based fatty acid methyl ester disulfide (FAME-S₂) was synthesized in good yield by oxidation of polymercaptanized soybean oil fatty acid methyl ester (PM-FAME). The chemical structure of FAME-S₂ is of interest because of its potential as a biobased multi-functional additive in lubricant formulations. Neat FAME-S₂ and their blends (1–10% w/w) in polyalphaolefin (PAO-6) and high oleic sunflower oil (HOSuO) were characterized for its chemical, physical and tribological properties. Blends of FAME-S₂ in HOSuO relative to similar blends of PM-FAME displayed higher oxidation onset temperature (> 15 °C) that remained constant with increasing concentration. Evaluation of FAME-S₂ as an extreme pressure (EP) additive on a 4-ball tribometer showed increasing weld point (WP) with increasing concentration to a maximum of 220 and 180 kgf in HOSuO and PAO-6, respectively, at 10% w/w concentration. The results indicate that FAME-S₂ has both anti-oxidant and EP properties and can be applied as a multi-functional biobased additive in lubricant formulation. This work demonstrates an encouraging progress towards the development of effective biobased lubricant additives.

中文翻译：

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大豆脂肪酸硫化甲基酯的合成与表征

大豆基脂肪酸甲酯二硫化物（FAME-S ₂）通过聚合硫醇化大豆油脂肪酸甲酯（PM-FAME）的氧化反应以高收率合成。FAME-S ₂的化学结构备受关注，因为它在润滑剂配方中作为生物基多功能添加剂的潜力。整洁的FAME-S ₂及其在聚α-烯烃（PAO-6）和高油酸葵花籽油（HOSuO）中的共混物（1-10％w / w）具有化学，物理和摩擦学特性。相对于类似的PM-FAME掺合物，HOSuO中的FAME-S ₂掺合物表现出更高的氧化起始温度（> 15°C），并随着浓度的增加而保持恒定。FAME-S _2的评估因为在4球式摩擦计上的极压（EP）添加剂在HOSuO和PAO-6中的浓度分别为10％w / w时，焊点（WP）随浓度的增加而增加，最大分别为220和180 kgf。结果表明，FAME-S ₂具有抗氧化剂和EP特性，可以作为多功能生物基添加剂用于润滑剂配方。这项工作表明，在开发有效的生物基润滑剂添加剂方面取得了令人鼓舞的进展。