ABSTRACT:Octafluoropentyl acrylate [H(CF 2 CF 2 ) 2 CH 2 -C(O)CHACH 2 ] and polycaproamide (PA-6) thread were copolymerized with a tert-butyl hydroperoxide initiator. The fluorine content of the thread was 0.87-1.33% after copolymerization. The creation of ester polyfluorinated alkyl groups on the end of the polyamide macromolecules by the homolytical substitution of hydrogen atoms in the ␣-CH 2 O group of the OHNOCH 2 O(CH 2 ) 4 OC(O)O chain led to an increase in the tensile strength of the PA-6 thread.