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One of the major disadvantages of vegetable oils as base stock for lubricants is their high pour points. In this paper the crystallisation behaviour of coconut oil and the effect of additive addition and the chemical modification on its pour point were analysed using differential scanning calorimetry (DSC). Coconut oil showed the highest pour point among the vegetable oils considered in the study. This can be attributed to the predominantly saturated nature of its fatty acid constituents. Addition of additives did not show any significant improvement in the pour point of coconut oil. The chemical modification procedures described in this work have been effective in improving the pour point of coconut oil to some extent. The DSC method used in the present work has been found to be helpful in understanding the crystallisation behaviour of vegetable oils with different fatty acid compositions, the effect of additive addition and the chemical modification on pour point of coconut oil. Copyright © 2008 John Wiley & Sons, Ltd.

This paper presents the study of the oxidative behaviour of vegetable oils using Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR) spectroscopic methods and thermogravimetric analysis/differential thermal analysis (TGA/DTA) techniques. The properties of vegetable oils were determined by their fatty acid (FA) composition. A high content of polyunsaturated FAs, like linoleic and linolenic acids, decreases thermal-oxidative stability. FTIR spectroscopy can be used as a quick method to measure the degree of unsaturation in vegetable oils in a qualitative manner. NMR spectroscopy can be used to quantitatively evaluate the degree of unsaturation in vegetable oils. TGA/DTA techniques were used to evaluate the oxidative properties of vegetable oils. In the present study, TGA/DTA analyses was performed on different vegetable oils under isothermal conditions at 150 °C for 3 hours. TGA/DTA thermograms showed weight changes and thermal activities in terms of exothermic or endothermic heat fl ows during the oxidative reactions. The oxidative degradation was evaluated in terms of the weight gain by the respective vegetable oils under the test conditions, due to the formation of oxidative polymerization products and the value of exothermic peaks as obtained from the DTA. The comparative study of the oxidative performance of different vegetable oils showed that the higher the degrees of unsaturation, the higher are the weight gains and the exothermic peaks. The evaluation of the effect of a chosen antioxidant showed marked improvement on the oxidative stability of vegetable oils.

In this paper Spartan 02, a molecular dynamics software, is used to analyze and predict the tribological properties of coconut oil in a qualitative manner on the basis of carbon chain length of the constituent fatty acids, their polarity (net electrostatic charge, Qr), the energies of the molecular orbitals E_HOMO (energy of the highest occupied molecular orbital), and E_LUMO (energy of the lowest unoccupied molecular orbital), and the heats of formations (H-Form) of the iron soaps of respective fatty acids. Tribological properties of the constituent fatty acids of coconut oil were evaluated using a four-ball tester as per ASTM D4172 method. The experimental results showed good correlation to the selected quantum chemical descriptors. The influence of an anti-wear additive on the tribological performance of coconut oil and the optimum additive concentration were also evaluated experimentally.