Composites of polyamide-6 (PA-6) and poly(butadiene acrylonitrile) (PBAN), varying in the quantity of the elastomer and the content of its nitrile groups, were examined during extrusion in a 45-mm extruder at 225 +/- 2degreesC and with a shear rate over 450 s(-1). It was established that these two incompatible polymers can be mixed and the blends display solubility in formic acid. This fact is explained by chemical transformation of the nitrile groups followed by chemical interaction between the polyamide and elastomer components. As a result, graft copolymers were most probably formed. The reaction proceeds easily if the PA-6 contains water. The extrusion leads to improved compatibility of the polymers and enhanced impact strength of the extrudates. (C) 2004 Wiley Periodicals, Inc.