Non-random lattice fluid model and its application in polymer solutions and blends.

摘要

A generalized non-random lattice fluid model (NRLF) is developed based on lattice statistical mechanics. The complete partition function is constructed to account for both compressibility and non-randomness. Hydrogen bonding forces are treated distinguishable from ordinary van der Waals forces because of their large values and high ordering. The two types of intermolecular forces are coupled and affect each other. A general formalism makes the model suited not only for hydrogen bonding systems but also non-polar or polar systems without hydrogen bond. The model is constructed as simply so that all the main thermodynamic functions can be expressed analytically. It has been proved useful over an extended range of applications: from small molecules to polymers, from pure fluids to mixtures, from the saturated region to supercritical region, and from mixing thermodynamic properties to liquid-vapor phase transition. It is valid for various typical fluids including water, hydrocarbons, alcohols and polymers.; A new technique, called the heat of dilution method, is devised to extract interaction parameters of solvent-polymer and polymer-polymer. The advantage of this method is that it can avoid the problems caused by high liquid viscosity and transition heats from the glass and crystalline phases. It has been applied successfully to obtain interaction parameters for two polymer systems polystyrene/poly(2,6-dimethyl phenylene oxide) and poly(methyl methacrylate)/poly(ethylene oxide). The results from this method are found to be consistent with those from other calorimetry methods such as heat of solution method and small molecular analog calorimetry.; The hydrogen bonding and end group effect on the PVT behavior and solution thermodynamic properties of four polymers poly(ethylene glycol), poly(ethylene glycol) dimethyl ether, poly(ethylene glycol) mono-methyl ether and poly(propylene glycol) have been investigated both theoretically and experimentally. The theoretical calculations by NRLF model are in good agreement with all the experimental data of PVT, heat of mixing and densities of mixtures using only one pair of hydrogen bonding parameters for each type of hydrogen bond.