Synthesis and PhysicalProperties of TriacylglycerolOligomers: Examining the Physical Functionality Potential of Self-MetathesizedHighly Unsaturated Vegetable Oils.

Seven model oligomers (from dimer to octamer) of thetriacylglycerol(TAG) triolein were synthesized from oleic acid and fully characterizedby 1H NMR, 13C NMR, mass spectroscopy, and gelpermeation chromatography (GPC). The thermal stability of the oligomersas determined by TGA was excellent, with degradation beginning at342 °C for the most thermally labile samples. The samples allpresented glass transitions at low temperatures, with Tgcontinuously shifting to higher temperatures with increasingnumbers of monomers. The crystallization and melting behavior scaledwith molecular size and relative number of double bonds in the trans-configuration. Flow behavior was investigated over a large range oftemperatures (−10 to 110 °C), and application of the Herschel–Bulkeymodel to shear stress versus shear rate data evidenced a flow behaviordependent on molecular size and temperature. The oligomers presenteda thinning to Newtonian flow transition temperature proportional tomolecular size. The viscosity versus temperature data, fitted witha generalized van Velzen equation, suggested that it is the competitionbetween the trans- character and size of the molecules which determinesthe rheology of these molecules. Overall, all the investigated propertiesplateaued at the hexamer, suggesting that no further marginal utilitycan be obtained with larger oligomers. [ABSTRACT FROM AUTHOR]