Compatibility studies of blends of a thermotropic liquid crystalline polymer and flexible chain polymers by application of Flory's lattice theory

Flory's lattice theory has been applied to the polymer blends containing a thermotropic liquid crystalline polymer (LCP) and flexible chain polymers. The phase behavior of blends of a thermotropic LCP and a flexible chain pol ymer at melt processing temperature can be evaluated by two quantitative pa rameters: the polymer-polymer interaction parameter (chi (12)) and the degr ee of disorder (y/x(1)). From the results of the model calculation, it has been found that the miscibility is increased with the increase of the degre e of disorder (y/x(1)) of the LCP and with the decrease of the degree of po lymerization (x(1)m and/or x(2)) The simulated spinodal curve of ternary po lymer blends containing a thermotropic LCP and two flexible chain polymers has been calculated using the lattice theory. When three pairs of binary po lymer blends are immiscible, the coexistence curve of the three phases appe ars for the ternary blend having similar values of Xi, among component poly mers. When the LCP is immiscible with two flexible chain polymers, and also when the two flexible chain polymers are miscible with each other, the str ong effect of anisotropy of the LCP is observed in the simulated spinodal c urve. When three pairs of binary polymer blends are miscible, a phase separ ation is also observed due to the \Delta chi\ effect. (C) 2000 Elsevier Sci ence Ltd. All rights reserved.