Submitted to: Thermochimica Acta
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/9/2002
Publication Date: 1/20/2003
Citation: ADHVARYU, A., ERHAN, S.Z., PEREZ, J.M. WAX APPEARANCE TEMPERATURES OF VEGETABLE OILS BY TEMPERATURE MODULATED DSC: EFFECT OF TRIACYLGLYCEROL STRUCTURE AND ITS MODIFICATION. THERMOCHIMICA ACTA, 2003. v.395. pp.191-200. Interpretive Summary: Vegetable oils can be used as a substitute for mineral oil based lubricants if their low temperature behavior is improved. This work presents a method for a rapid estimation of vegetable oil solidification at low temperature. The method also discusses how the solids are formed and how they can be prevented in vegetable oils. Mathematical equations are developed that can predict the solidification to a high degree of accuracy. This is useful for a rapid screening of oils for industrial lubricant application.
Technical Abstract: Low temperature wax appearance and crystallization phenomena of a series of vegetable oils and those derived from genetically and chemically modified oils were studied using temperature modulated differential scanning calorimetry. Effect of the structure of fatty acid chain and their 'tuning fork' conformation during cooling process was studied. The method describes an approach to quantify the wax appearance temperature form DSC cooling curve exotherm for a series of vegetable oils (with varying fatty acid composition) and predicted in terms of 1H NMR derived structural data using statistical analysis. Various triacylglycerol molecules with different fatty acid (e.g. oleic and linoleic) chains were designed using a molecular modeling program to illustrate their relative crystallization tendency based on steric and geometrical constrains. Effect of pour point depressant (PPD) additive on the crystallization behavior of heat and chemically modified vegetable oils are also discussed.