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Chemiluminescence Study of the Autoxidation of cis-1,4-PolyisopreneThe free-radical mechanism for the autoxidation of cis-1,4-polyisoprene (natural rubber or its synthetic counterpart) has been investigated extensively. An important feature of this mechanism, and indeed also of the autoxidation of hydrocarbons generally, is that it is a chain process propagated by alkyl and peroxy radicals and terminated through bimolecular reactions involving these same radicals. In the usual oxidation situation, that is, at all oxygen pressures greater than a few torr, the alkyl radicals are rapidly converted to peroxy radicals, and the termination step proceeds almost exclusively through the latter radicals. The bimolecular decay of the peroxy radicals is accompanied by a weak emission of light or chemiluminescence. Kinetic evidence is consistent with an electronically excited ketone produced in the termination reaction as the source of the emission. The first observation of chemiluminescence from the oxidative degradation of polymers was reported by Ashby, who dealt mainly with polypropylene but made passing mention of several other polymers. Subsequently, a number of papers have appeared dealing with oxidative chemiluminescence from a variety of polymers. In this paper we report the first detailed study of the chemiluminescence emitted in the autoxidation of cis-1,4-polyisoprene. The chemiluminescence technique is extremely sensitive and can follow rates of oxidation that are too slow to be measured conveniently by other means. This work thus offered the potential of throwing new light on the autoxidation of cis-1,4-polyisoprene, especially in the very early stages or under ambient conditions where conventional spectroscopic procedures are rather insensitive.
Document ID
19990071250
Acquisition Source
Ames Research Center
Document Type
Reprint (Version printed in journal)
Authors
Mendenhall, G. David
(Battelle Columbus Labs. OH United States)
Nathan, Richard A.
(Battelle Columbus Labs. OH United States)
Golub, Morton A.
(NASA Ames Research Center Moffett Field, CA United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1978
Publication Information
Publication: Applications of Polymer Spectroscopy
Publisher: Academic Press, Inc.
ISBN: 0-12-125450-X
Subject Category
Chemistry And Materials (General)
Funding Number(s)
CONTRACT_GRANT: NAS2-8195
Distribution Limits
Public
Copyright
Other

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