AROMATIC POLYAMIDE BLENDS - ENTHALPY RELAXATION AND ITS CORRELATION WITH PHASE PHENOMENA

The phase behavior of blends containing only aromatic polyamides has been investigated, and the results compared with a predictive treatment founded upon a mean-field binary interaction model. The similarity of structure and composition of the polymers, and hence the close proximity of the respective glass transition temperatures, necessitated the implementation of the technique established by Ellis and ten Brinke to evaluate phase phenomena within the blends. Relying on the structural dependence of the kinetics of enthalpy recovery, this technique has proven to be very sensitive and provides information that is available by no other technique. The prediction of immiscibility was found to be supported in most cases and confirms the axiom that polymers of similar constitution will not form homogeneous mixtures. Noted exceptions to this rule were also found, suggesting that there exists the potential for subtle behavior that is not yet accounted for. The elements possibly contributing to this are addressed and discussed in terms of the applicability of a binary interaction model to blends of this nature. © 1990, American Chemical Society. All rights reserved.