OPEN-CELL MODEL EQUATION OF STATE FOR LIQUIDS .1. P-V-T BEHAVIOR FOR LIQUIDS AND LIQUID POLYMERS

An open-cell model equation of state has been proposed, which relaxes the restrictions of the cell theory and allows more flexibilities in d escribing the structure of liquids. To test its capability, this equat ion has been applied to a variety of liquids, including 17 heavy molec ular weight hydrocarbons, 10 organic solvents, and 15 polymers, in par ticular. The calculated density grand average AAD rho for the equation proposed here are 0.062, 0.057, and 0.054 per cent against the result s for the equation of state by Simha and Somcynsky, 0.081, 0.093, and 0.072 percent for the above three groups of liquids, respectively. Goo d agreement between our calculated results and experimental data indic ates that our model is an improvement,over the Simha and Somcynsky equ ation of state, which has been evaluated as one of the best equations. Moreover, this equation can be easily extended to describe the proper ties of polymer solutions and polymer blends, which will be addressed in our subsequent paper.