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Absolute Viscosity and Density of Trisubstituted Phosphoric Esters

Kannan, S and Kishore, K (1999) Absolute Viscosity and Density of Trisubstituted Phosphoric Esters. In: Journal of Chemical And Engineering Data, 44 (4). pp. 649-655.

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Abstract

This paper presents measurements on the absolute viscosity (eta) and density (rho) of trisubstituted phosphoric esters which are useful in understanding their now mechanism necessary for accessing their role as plasticizers. The effect of chain length and branching has been examined on the eta and rho trends. From eta data, by using the Vogel-Tammann-Fulchur (VTF) equation, the VTF temperature (T-o) has been obtained which also represents the ideal glass transition temperature. T-o is related to the flexibility of the molecules. It is observed that T-o initially decreases with molecular weight, reaches ii minimum, and increases thereafter. The initial decrease in T-o has been attributed to the enhanced flexibility of the phosphate esters. Reversal of flexibility with relative molar mass beyond 400 is due to the gentle collision of the arms of the trisubstituted phosphoric esters. This has been further corroborated from the molar mass exponent as exhibited in the eta-molar mass plot. The isomeric effect on eta has also been investigated in tricresyl phosphates, hitherto for the first time. The ortho isomer has highest eta among the isomers. The para isomer was found to have lowest T-o and hence highest flexibility compared to the ortho and meta isomers.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to American Chemical Society.
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 31 Dec 2008 11:03
Last Modified: 19 Sep 2010 04:58
URI: http://eprints.iisc.ernet.in/id/eprint/17720

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