| Abstrakt: |
The relative viscosity coefficient $$ \left( {{\raise0.7ex\hbox{$\eta $} \!\mathord{\left/ {\vphantom {\eta {\eta_{0} }}}\right.\kern-0pt} \!\lower0.7ex\hbox{${\eta_{0} }$}}} \right) $$ and volumetric properties of mixtures of water with ethylene glycol (EG) and polyethylene glycols (PEGs) of molecular weights 400, 1000 and 4000 g·mol (PEG-400, PEG-1000 and PEG-4000) in the concentration range of ~0.01 to ~0.5 mol·kg, or up to 0.1 volume fraction ( $$ \phi_{2} $$ ), have been measured at three temperatures (293.15, 298.15 and 303.15 K) and at ambient pressure. The data were subjected to analysis by applications of the Jone-Dole equation, Vand's equation with the viscosity parameters B and D, particle interaction coefficients ( Q), Einstein-Simha factor ( $$ \nu $$ ), and hydration number ( h) were determined at different temperatures. Using the density data, the limiting apparent molar volumes ( $$ \phi_{\text{V}}^{0} $$ ) at different temperatures, and the limiting apparent molar expansivity ( $$ \phi_{\text{E}}^{0} $$ ) at 298.15 K, were obtained. Positive values of the viscosity B coefficients were observed for all the studied systems; these decrease with increase in temperature, while the D coefficients are also necessary to represent the data, showing specific behavior depending upon the chain length of the polymeric molecules. The larger viscosity increments in excess of the Einstein-Simha volume contributions, and decreasing hydration numbers with increasing temperature, are attributed to the water structure-making effect, solute-solvent hydrogen bond interaction and the presence of hydrophobic interaction between the chain segments of the polymeric molecules. The resulting D coefficients and the virial coefficients are examined from the point of view of solute-solute association. [ABSTRACT FROM AUTHOR] |
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