Journal of the American Oil Chemists' Society

, Volume 77, Issue 2, pp 111–114 | Cite as

Rheology of vegetable oil analogs and triglycerides

Article

Abstract

The rheological properties of two complex mixtures of short-chain triglycerides were experimentally determined. Dynamic or absolute viscosities of the mixtures were measured for shear rates of 0.32 to 64.69 s−1 at temperatures between 25 and 80°C. The compositions of the mixtures were based on the oil of the plant species Cuphea viscosissima VS-320, a natural source of short-chain triglycerides. The dynamic viscosities of these mixtures were compared to those of a traditional vegetable oil (peanut oil) and diesel fuel. The results of this comparison were used to make estimates of the performance of such triglyceride mixtures as diesel fuel substitutes, since viscosity can be a key indicator of fuel performance for possible substitute diesel fuels. The crystallization temperatures of these two mixtures were also determined experimentally, and the effects of crystallization on fuel performance were projected. Additionally, the dynamic viscosities of pure triglycerides from C6∶0 to C18∶0 at 75°C were plotted vs. chain length. These viscosities were measured at high shear rates (>6 s−1) where dynamic viscosity is shear-independent. An obvious trend in the relationship between triglyceride chain length and viscosity was observed. A second-order regression was used to obtain an equation for this relationship. This equation was used as a model for composition dependence of viscosity. This model was applied to the viscosities of the triglyceride mixtures examined here. There was good agreement between the model and the actual, measured viscosity values determined in this study.

Key Words

Biodiesel crystallization temperature Cuphea short-chain triglycerides vegetable oil viscosity 

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References

  1. 1.
    Eiteman, M.A., and J.W. Goodrum, Density and Viscosity of Low-Molecular-Weight Triglycerides and Their Mixtures, J. Am. Oil Chem. Soc. 71:1261–1265 (1994).Google Scholar
  2. 2.
    Eiteman, M.A., and J.W. Goodrum, Rheology of the Triglycerides Tricaproin, Tricaprylin, and Tricaprin and of Diesel Fuel, Trans. ASAE 36:503–507 (1993).Google Scholar
  3. 3.
    Goodrum, J.W., and M.A. Eiteman, Physical Properties of Low Molecular Weight Triglycerides for the Development of Biodiesel Fuel Models, Bioresour. Technol. 56:55–60 (1996).CrossRefGoogle Scholar
  4. 4.
    Goodrum, J.W., D.P. Geller, and S.A. Lee, Rapid Measurement of Boiling Points and Vapor Pressure of Binary Mixtures of Short Chain Triglycerides by TGA Method, Thermochim. Acta 311:71–79 (1998).CrossRefGoogle Scholar
  5. 5.
    Valeri, D., and A.J.A. Meirelles, Viscosities of Fatty Acids, Triglycerides, and Their Binary Mixtures, 74:1221–1226 (1997).Google Scholar
  6. 6.
    Geller, D.P., J.W. Goodrum, and S.J. Knapp, Fuel Properties of Oil from Genetically Altered Cuphea viscosissima, Ind. Crops Prod. 9:85–91 (1999).CrossRefGoogle Scholar
  7. 7.
    Knapp, S.J., Modifying the Seed Storage Lipids of Cuphea: A Source of Medium-Chain Triglycerides, in Seed Oils for the Future, edited by S.L. MacKenzie and D.C. Taylor, AOCS Press, Champaign, 1992, pp. 142–154.Google Scholar
  8. 8.
    Bailey, A.E., Bailey’s Industrial Oil and Fat Products, Wiley Publishing, New York, 1979, Vol. 1, p. 84.Google Scholar
  9. 9.
    Knapp, S.J., L.A. Tagliani, and W.W. Roath, Fatty Acid and Oil Diversity of Cuphea viscosissima: A Source of Medium-Chain Fatty Acids, J. Am. Oil Chem. Soc. 68:515–517 (1991).Google Scholar
  10. 10.
    Gunstone, F.D., J.L. Harwood, and F.B. Padley, eds., The Lipid Handbook, Chapman and Hall, London, 1986, p. 81.Google Scholar

Copyright information

© AOCS Press 2000

Authors and Affiliations

  1. 1.Department of Biological and Agricultural EngineeringUniversity of GeorgiaAthens
  2. 2.Driftmier Engineering CenterAthens

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