Radical formation during the tensile failure of polymer fibers

Bond rupture associated with the tensile deformation of oriented Nylon 6 has been studied by electron spin resonance (ESR). Two samples were investigated, a single monofilament (“bristle”) and a commercial low twist yarn. Experiments with the monofilament show that tensile deformation has substantial irreversible effects on the free radical concentration observed at failure, but no effect on the ultimate properties of the fiber. It was also demonstrated that the stress‐strain behavior of the yarn is quite different from that of the fibers near the ultimate extension. These present experiments raise serious questions as to the correctness of previous reports in which the bond breakage observed by ESR is assumed to uniquely determine the deformation and fracture process.