Water activities in binary and ternary aqueous systems of poly(ethylene glycol), poly(propylene glycol) and dextran

The vapor pressure osmometry (VPO) measurements were used to obtain activit ies of water for aqueous solutions of poly(ethylene glycol)/dextran and pol y(ethylene glycol)/poly(propylene glycol) at temperatures 35 degreesC, 45 d egreesC, 55 degreesC and 65 degreesC. The weight fractions of water were va ried from 70% to 98%. To increase the accuracy, the calibration constants o f the VPO apparatus for each measurement were also determined. The experime ntal results were used in Flory-Huggins theory to calculate the interaction parameters for the mixtures and the results were discussed in terms of Flo ry-Huggins theory for evaluating other thermodynamic properties. (C) 2001 E lsevier Science Ltd. All rights reserved.