Phase equilibria and microstructures for polymer-solvent mixtures

Abstract

A description for blob solution was presented in polymersolvents mixtures. This could be explained for the solution states, which related the phase separation and equilibrium concentrations. A new calculation method for binary polymer-solvent mixtures has been developed in terms of blobs of polymers and used the successive renormalization of lattice and local composition model in calculating interactions with their neighboring sites. The blobs of having various sizes and molecular weights are incorporated for the effective interaction energies of sites in the decorated UNIQUAC. And, norther structural factor of the blob, q, representing the ration of surface area, was introduced assuming that the shape of blobs and the blob weight closely related to the step size g, is averaged along with $\xi$. For polyethylene glycol-water systems of a closed-loop diagram, the proposed method fairly reproduced the size and shape of the region of phase separations. The temperature-independent interaction parameters were used in the range of -5.0 to -7.0 Kcal/mol for directional and adjusted for nondirectional. In estimating the phase diagram, the blob size, which depends on not only the chain properties of the polymer but also the solution state, increases if the chain of polymeri is rigid and for poor solvent. (chapter 3) Also, this calculation method was applied for liquid-liquid equilibria of polymeric ternary systems involving two polymers and solvent. It incorporates the blob concept of polymer chains and he renormalization scheme for primary blobs to rescaled blobs, which we called pseudocomponents, the basic units that are responsible for intermolecular interactions. Following the conventional algorithm with the pseudocomponents, the phase equilibria are calculated in elms of the size and the binary interaction parameters of local composition models. Phase diagrams of two distinct characteristic have been examined. The first is typified by polystyrenes of two different ...