Middle macroradicals and their influence on the strength of oriented polymers

The macroradicals formed through the detachment of hydrogen atoms in amorphous-crystalline polymers are studied using electron-nuclear double resonance (ENDOR) spectroscopy. The H-1 ENDOR spectra are analyzed, and the hyperfine interaction constants of the nearest neighbor and remote protons are measured. The conformational structure of radicals in poly(ethylene) (PE), poly(propylene) (PP), and poly(caproamide) (PCA) is determined. The ENDOR and EPR spectra of fibers subjected to tensile loading are recorded. It is revealed that torsional strain arises in the radicals with a nonplanar structure. The results of mechanical testing of irradiated oriented polymers demonstrate that the weakening of β bonds in the radicals has an effect on the macroscopic strength. © 2005 Pleiades Publishing, Inc.