ISSN:
0021-8995
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Moldings were irradiated at ambient temperature in vacuo with 2 m.e.v. electrons to doses of 5.9-7.3 Mrad. The decay of radicals was followed by EPR spectroscopy at 80, 55, and 30°C. while simultaneous extinction measurements were made at 300-700 mμ with a recording spectrophotometer. The radical decay data indicated the presence of three species at each temperature, decaying exponentially with time, with half-lives of 20 min., 210 min., and 135 hrs. at 80°C. of 40 min., 400 min., and 141 hrs. at 55°C., and of 54 min., 720 min., and 3200 hrs. at 30°C. G values of 1.6, 2.0, and 1.4 were obtained for radical formation at 25°C. by back-extrapolation of decay curves from the three temperatures to the end of the irradiation period. The activation energy of radical decay was found to be 4.4, 5.0, and 13.7 kcal./mole for the short-lived, intermediatelived, and long-lived radicals, respectively. The optical data has a broad absorption maximum at 500-550 mμ and a series of seven absorption peaks with maxima at 505-510, 483-485, 458-460, 430-435, 400-405, 364-365, and 329-330 mμ. The concentration of the material producing the broad bands was found to be inversely proportional to the long-lived radical concentration. The fine-structure peaks are consistent with literature data for a polyene chain of 16-17 conjugated double bonds.
Additional Material:
18 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1963.070070424
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