The influence of strong centrifugal force fields on solutions: I. Improved Hermans-Ende equation

Autor(en): Lechner, MD
Borchard, W
Stichwörter: DENSITY GRADIENT; Polymer Science; POLYSTYRENE
Erscheinungsdatum: 1999
Herausgeber: PERGAMON-ELSEVIER SCIENCE LTD
Journal: EUROPEAN POLYMER JOURNAL
Volumen: 35
Ausgabe: 3
Startseite: 371
Seitenende: 376
Zusammenfassung: 
An improved Hermans-Ende equation for real solutions has been derived in order to calculate the density as a function of the radial distance in a density gradient mixture (components of low and high density) inside an ultracentrifugal cell. The equation is based on the model with vanishing mixing volume with the barometric equation and the extended Flory-Huggins-van Santen-Staverman equation for the free energy of mixing. The equation has been tested with equilibrium density gradient measurements of the system water/metrizamide/polystyrene latex where metrizamide is the high density medium. The overall or initial concentration of metrizamide in the mixture was 8-12% by weight. The latex concentration was 0.03% by weight. It is demonstrated that the density gradient is highly influenced due to nonideality effects with respect to the solvent composition. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.
ISSN: 00143057
DOI: 10.1016/S0014-3057(98)00134-7

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