Polymer blends based on a rigid-rod aramid poly (2-chloro-1,4-phenylene terephthalamide) (CIPPTA) and an amorphous nylon poly(hexamethylene isophthalamide) (nylon 6I) were prepared by coprecipitation, and pressed into films by hot-compression. By differential scanning calorimetry (d.s.c.), optical microscopy and dynamic mechanical thermal analysis (d.m.t.a.), formation of a co-continuous superstructure in the blend films was suggested. The blend films exhibited high heat resistance and high stiffness, which are ascribable to the continuous aramid phase characteristic of the co-continuous structure. Copyright (C) 1996 Elsevier Science Ltd.