화학공학소재연구정보센터
Journal of Chemical Thermodynamics, Vol.40, No.8, 1200-1207, 2008
Interactions of polyethylene glycols with water studied by measurements of density and sound velocity
Densities and sound velocities of ethylene glycol (EG) and polyethylene glycols (PEGS) of molecular weight 200, 300, 400, 550, 600, 1000, 1450, 3350, 8000, and 10,000 at (288.15, 298.15, and 308.15) K were measured with high precision vibrating tube densimeter and sound velocity measuring device. They were used to evaluate apparent molar volumes, V-empty set, and apparent molar isentropic compressibilities, K-empty setS. Infinite dilution values of these parameters, V-empty set degrees, and K-empty setS degrees, were obtained from their plot as a function of molality. The variations of V-empty set degrees, and K-empty setS degrees, with the number of repeating units in PEGS and with temperature were examined. Comparison of the experimentally obtained data was made with the available literature data and also with some values predicted according to group additivity approach. The results were interpreted in terms of hydration and conformational effects of PEGS in water. A correlation was also examined between V-empty set degrees or K-empty setS degrees values of PEGS in water and equilibrium moisture contents of PEGS as well as the water vapor permeabilities (WVP) of edible films containing PEGS. (C) 2008 Elsevier Ltd. All rights reserved.