Temperature dependence of the oxidative stability of corn oil and polyalphaolefin in the presence of sulfides

• Published in: Thermochimica acta Vol. 513; no. 1; pp. 94 - 99
• Main Authors: Bantchev, Grigor B., Biresaw, Girma, Mohamed, Abdellatif, Moser, Jill
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier B.V 01.01.2011; Elsevier
• Subjects: Applied sciences; Autoxidation; Bio-based lubricant; Biological and medical sciences; Chemical industry and chemicals; Differential scanning calorimetry; Exact sciences and technology; Fat industries; Food industries; Fundamental and applied biological sciences. Psychology; Miscellaneous; Oils and fats; Polyalphaolefin; Polysulfide; Pressure DSC; Sulfide; Vegetable oil; Autoxidation; Polysulfide; Sulfide; Differential scanning calorimetry; Pressure DSC; Bio-based lubricant; Polyalphaolefin; Vegetable oil; Temperature effect; Mineral oil; Polysulfides; Edible oil; Operating conditions; Lubricant; Petrolatum; Sulfides; Oxidation resistance; Corn oil; Olefin polymer; Thermal analysis
• ISSN: 0040-6031; 1872-762X
• DOI: 10.1016/j.tca.2010.11.017

The effect of sulfide-modified corn oil (SMCO) and ditertiary dodecyl pentasulfide (PS) additives on the oxidative stability of corn oil (CO) and polyalphaolefin oil (PAO) was investigated using pressurized differential scanning calorimetry in dynamic (DDSC) and isothermal (IDSC) modes. DDSC showed a weak pro-oxidant effect of SMCO and PS in CO, and antioxidant behavior in PAO. Analysis of the IDSC data showed the existence of isokinetic temperature in both oils. Below the isokinetic temperature the sulfides behaved as antioxidants while above it they behaved as pro-oxidants. The isokinetic temperature was found to depend on the chemical structure of the oils. For the highly unsaturated CO, the isokinetic temperature was 100–135 °C, while for the fully saturated PAO it was above 200 °C. The existence of isokinetic temperature provides consistent explanation to our and literature data for oxidation behaviors of sulfide additives in oils, which appears to be contradictory (pro-oxidant vs. antioxidant) depending on experimental conditions. The isokinetic temperature suggests that accelerated oxidation test methods at elevated temperatures are poor predictors of the low-temperature performance of sulfide-containing antioxidants.