ISSN:
0360-6376
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The behaviors of free radicals produced in polyethylene irradiated with ultraviolet light and electron beams were compared in connection with primary processes of radical formation and trapping regions of free radicals. In the case of irradiation with ultraviolet light, an ESR spectrum observed at -196°C immediately after irradiation is an eight-line spectrum due to alkyl radicals of the type —CH2—ĊH—CH3, while in the case of ionizing radiation, a six-line spectrum due to —CH2—ĊH—CH2— was observed. The former radicals are produced by the Norrish type I reaction of the carbonyl groups contained in the polymer, followed by radical rearrangement; and the latter are formed by dissociation of hydrogen atom from the excited state of the polymer or ion-molecular reactions. From the sensitivity to oxygen molecules, it was deduced that free radicals are trapped in amorphous regions after ultraviolet irradiation, but mainly in crystalline regions after irradiation with electron beams. Saturation studies of ESR spectra seem to support this conclusion.
Additional Material:
10 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1973.170110624
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