CHEMISTRY OF IRRADIATION INDUCED OF POLYTETRAFLUORO ETHYLENE RADICALS. VOLUME I: RE-EXAMINATION OF THE EPR SPECTRA.
Rept. for Jan 66-Jan 67,
AEROSPACE CORP EL SEGUNDO CA LABS DIV
Pagination or Media Count:
The electron paramagnetic resonance EPR spectra of the radicals formed during the gamma-irradiation of polytetrafluoro ethylene PTFE are examined and assigned. It is shown that both chain radicals e.g., RCF2CFCF2R and propagating radicals e.g., RCF2CF2 are formed and stabilized when PTFE is irradiated in vacuum and at room temperature the yield of the chain radical is ten times that of the propagating radical. When PTFE is irradiated in air the peroxide radicals RCF2CFOOCF2R and RCF2CF2OO are stabilized. The difference in yields of the two peroxide radicals is a function of total dosage, with the relative contribution of RCF2CF2OO increasing with increasing dose. Both of the peroxide radicals are converted to the RCF2CF2 radical when they are irradiated with ultraviolet light in vacuum. Some chain radical is produced by the photolysis of its peroxide, but the yield of the propagating radical is fifty times that of the chain radical. The EPR spectrum of the RCF2CF2 radical consists of three sets of lines. The central set is a well resolved triplet with a splitting between adjacent lines of 16 plus or minus 0.5 G. The wing lines are broadened by anisotropic nuclear hyperfine interactions, and the expected triplet structure is not resolved. From the room temperature spectrum, it is estimated that the isotropic component of the alpha- fluorine interaction is about 85G. Also, from the 77 K spectrum, it is estimated that the maximum anisotropic component of the hyperfine interaction tensor is about 140G. The g-value for this radical is 2.0038 plus or minus 0.0001. Author
- Radiation and Nuclear Chemistry