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Radiation chemical effects on polybutadiene polymers, styrene-butadiene block copolymers, and isotactic polypropylene

Thesis/Dissertation ·
OSTI ID:6203321
Electron spin resonance (ESR) of the free radical structure resulting from high energy gamma LNT irradiation of the polymers revealed the presence of allylic free radicals of the type approx. CH.CH = CH.CH/sub 2/ approx. The presence of chemically trapped electrons in polybutadiene and styrene-butadiene (SB) block copolymers irradiated in the absence of light at LNT was determined by ESR measurements, and the trapping sites were shown to be impurities or additive molecules which were imbedded in between the polymer chains and which had not been completely removed by purification. Reaction kinetic studies of free radical decay indicated that the decay followed the equation derived for the case in which some free radicals decay by a second order mechanism in the presence of nondecaying free radicals. The same reaction scheme was found to describe the kinetics of alkyl free radical decay in LNT irradiated quenched and annealed isotactic polypropylene with the decay rate of quenched samples being higher than for annealed samples. Results of studies of radiation-induced crosslinking of the elastomers are also included. (BLM)
Research Organization:
Baylor Univ., Waco, TX (USA)
OSTI ID:
6203321
Country of Publication:
United States
Language:
English