Densities of {poly(ethylene glycol) plus water} over the temperature range (283.15 to 363.15) K

Densities of tpoly(ethylene glycol) [PEG] + water) prepared with PEG average molar mass (200, 400, 600, and 1500) g " mol-1 have been measured over the entire composition range over the temperature range (283.15 to 363.15) K at 10K intervals using a density meter based on electromagnetically-induced oscillations of a U-shaped glass tube and an inbuilt Peltier thermostat. The density versus temperature data of (PEG + water) at each composition for all PEGs were fit to a simple quadratic equation: pkg " cm-3) = pogg " cm-3) + a(TIK)+ b(TIK)2. Fits were observed to be satisfactory at each composition for all four (PEG + water). The excess molar volumes of (PEG + water) are observed to be negative and significant over the entire composition range for all four (PEG + water). Irrespective of the temperature, the maximum absolute excess molar volumes are observed in the water-rich region of the mixture and are found to decrease with increasing temperature. This is attributed to the presence of strong interactions within the (PEG + water). Specifically, it is proposed to be due to the H-bonding interactions between the PEG and the water molecules within the mixtures. (C) 2010 Elsevier Ltd. All rights reserved.