Synthesis and Physical Properties of Triacylglycerol Oligomers: Examining the Physical Functionality Potential of Self-Metathesized Highly Unsaturated Vegetable Oils
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- 作者：Shaojun Li ; Laziz Bouzidi ; Suresh S. Narine
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2013
- 出版时间：February 13, 2013
- 年：2013
- 卷：52
- 期：6
- 页码：2209-2219
- 全文大小：487K
- 年卷期：v.52,no.6(February 13, 2013)
- ISSN：1520-5045
文摘
Seven model oligomers (from dimer to octamer) of the triacylglycerol (TAG) triolein were synthesized from oleic acid and fully characterized by 1H NMR, 13C NMR, mass spectroscopy, and gel permeation chromatography (GPC). The thermal stability of the oligomers as determined by TGA was excellent, with degradation beginning at 342 掳C for the most thermally labile samples. The samples all presented glass transitions at low temperatures, with Tg continuously shifting to higher temperatures with increasing numbers of monomers. The crystallization and melting behavior scaled with molecular size and relative number of double bonds in the trans- configuration. Flow behavior was investigated over a large range of temperatures (鈭?0 to 110 掳C), and application of the Herschel鈥揃ulkey model to shear stress versus shear rate data evidenced a flow behavior dependent on molecular size and temperature. The oligomers presented a thinning to Newtonian flow transition temperature proportional to molecular size. The viscosity versus temperature data, fitted with a generalized van Velzen equation, suggested that it is the competition between the trans- character and size of the molecules which determines the rheology of these molecules. Overall, all the investigated properties plateaued at the hexamer, suggesting that no further marginal utility can be obtained with larger oligomers.