Piyawan KrisanangkuraSupathra LilitchanKornkanok AryusukKanit KrisnangkuraMahidol UniversityKing Mongkut s University of Technology ThonburiBureau of Technical Support for Safety Regulation2020-01-272020-01-272019-01-01JAOCS, Journal of the American Oil Chemists' Society. Vol.96, No.1 (2019), 3-140003021X2-s2.0-85055248149https://repository.li.mahidol.ac.th/handle/20.500.14594/50536© 2018 AOCS In this study, the molecular compressibility (k m ) of a fatty-acid methyl ester (FAME) or a biodiesel is correlated with ΔG, (Formula presented.), via the Gibbs energy additivity method, where MW is the molecular weight of the FAME or the average MW of the biodiesel. The Gibbs energy associated with molecular compressibility ((Formula presented.)) is further correlated with the structure of FAME. Thus, the relationship between the structure (of a FAME or a biodiesel) and the physical property (k m ) is established. Thus, k m of a FAME at different temperatures can be easily estimated from the carbon numbers of fatty acid (z) and the number of double bonds (n d ) with good accuracy. For biodiesel, k m is calculated from the same equation with the average z (z (ave) ) and average n d (n d(ave) ). k m is not temperature independent and a slight change in k m depends on the structure of the FAME and biodiesel. For FAME having 14 carbon atoms or less in the fatty acid, k m decreases as temperature is increased. On the other hand, for FAME with a longer chain length (16 or higher), k m increases as temperature is increased. Similarly, a double bond in the long-chain FAME is more sensitive to temperature than the saturated FAME.Mahidol UniversityChemical EngineeringChemistryArticleSCOPUS10.1002/aocs.12162