Evaluation of physiochemical and tribological properties of rice bran oil - biodegradable and potential base stoke for industrial lubricants

The poor biodegradability of petroleum oils pressurizes the industry to develop ecofriendly biodegradable lubricants from agricultural feed stocks. The biodegradability, renewability, low toxicity and excellent lubricating performance of vegetable oils are the main reason behind the use of vegetable oil in the upcoming bio lubricant formulations. The vegetable oil generally has high flash point, fire point, high viscosity index, high lubricity and low evaporative losses. The properties of vegetable oil mainly depend on the nature (saturated/unsaturated) and composition of fatty acids present in the vegetable oils. In this paper, we are analyzing the feasibility of using rice bran oil as biodegradable lubricant base oil. The rheological, thermal, chemical and tribological properties of rice bran oil have been evaluated and conducted a gas chromatographic technique to understand its fatty acid profile. The oxidative stability was evaluated by hot oil oxidation test and differential scanning calorimetry. The coefficient of friction and wear scar dimension were evaluated by using a Four Ball Tester. The physiochemical and thermal properties of rice bran oil are found to be good compared to other vegetable oils and the commercially available mineral oil, SAE20W40. Rice bran oil has good frictional properties compared to SAE20W40 but the wear scar diameter is more for rice bran oil and can be improved by adding proper anti wear additives. (C) 2014 Elsevier B.V. All rights reserved.