EPR STUDY OF TEMPERATURE-DEPENDENT ROTATIONS OF POLYTETRAFLUOROETHYLENE CHAINS LABELED WITH PEROXY-RADICALS

The temperature dependence of the EPR spectra of peroxy chain radicals (R-CF2-CFOO′-CF2-R′) and peroxy propagating radicals (R″CF2-CF2OO) trapped in polytetrafluorothylene (PTFE) is studied in the range -196°C, +300°C, and analyzed in terms of the rotation freedom in the polymer. The peroxy propagating radical undergoes rotation along the polymer chain axis above -120°C, whereas the peroxy chain radical has the same rotation but only above -20°C. This difference is explained in terms of a particular mobility of the extremity of the carbon chain. Above -40 °C, the peroxy propagating radical rotates about the C-O bond in addition to the rotation about the chain axis. The additional rotation about the C-O bond is not observed below the decomposition temperature of the peroxy chain radical. © 1979 American Institute of Physics.