ANISOTROPY OF HYPERFINE SPLITTING IN ELECTRON PARAMAGNETIC RESONANCE SPECTRA OF IRRADIATED ORIENTED POLYMERS
An attempt was made to identify the radicals formed in irradiated polymers by the hyPerfine structure of the EPR spectrum. Experiments were made by stretching oriented polymers. The EPR spectra were taken at various angles between orientation and the magnetic field at 9000 Mc/sec. The investigation covered low-pressure polyethylene stretched in the cold state; polytetrafluoro ethylene (Teflon), stretched at 300 deg C; polyvinyl chloride stretched at 72 deg C; and polymethyl methacrylate stretched at 140 deg C. Irradiation was done either in a reactor (in evacuated quartz ampules at 40--50 deg C) or by a Au/sup 198/ needle (half-life 64.6 hr). The intensities of the lines and their number depend, in polyethylene, on the angle between elongation axis and magnetic field direction. This result is discussed on the basis of the formation of an alkyl radical which has four equivalent protons and a central H proton. Equations are derived on the basis of the projection of the protcns which are not equivalent. Data confirm the formation of an alkyl radical on irradiation at 77 deg K. Polyethylene irradiated at 40--50 deg C gave an EPR spectrum with 7 components, each of which was a doublet. This spectrum corresponds to a uniform interaction of an unpaired electron with 6 protons. This is believed to point to the formation of an allyl radical. Anisotropy was also observed in oriented Teflon; the spectra, however, were not analyzed. No anisotropy was observed with polyvinyl chloride and polyamide. The absence of anisotropy in polymethyl methacrylate and polystyrene is explained by the fact that there is no proton in the immediate vicinity of the unpaired electron that might cause, as with polyethylene, an anisotropy of hyperfine splitting. (OTS)
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-15-027677
- OSTI ID:
- 4839010
- Journal Information:
- Vysokomolekulyarnye Soedineniya, Journal Name: Vysokomolekulyarnye Soedineniya Vol. Vol: 2
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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AMIDES
ANISOTROPY
CHEMISTRY
CHLORIDES
ELECTRONS
FREE RADICALS
GOLD 198
HYPERFINE STRUCTURE
INTERACTIONS
IRRADIATION
MAGNETIC FIELDS
MAGNETIC RESONANCE
METHACRYLIC ACID
ORGANIC FLUORINE COMPOUNDS
POLYETHYLENES
POLYMERS
POLYSTYRENE
POLYVINYLS
PROTONS
QUARTZ
RESEARCH REACTORS
SPECTRA
VESSELS