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The application of a novel profluorescent nitroxide to monitor thermo-oxidative degradation of polypropylene

Micallef, Aaron S., Blinco, James P., George, Graeme A., Reid, Damien A., Rizzardo, Ezio, Thang, San H., & Bottle, Steven E. (2005) The application of a novel profluorescent nitroxide to monitor thermo-oxidative degradation of polypropylene. Polymer Degradation and Stability, 89(3), pp. 427-435.

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Abstract

The novel profluorescent nitroxide, 1,1,3,3-tetramethyldibenzo[e,g]isoindolin-2-yloxyl (TMDBIO) was investigated as a probe for the formation of polymer alkyl radicals during the thermo-oxidative degradation of unstabilised polypropylene. TMDBIO possesses a very low fluorescence quantum yield due to quenching by the nitroxide group; however, when the free-radical moiety is removed by reaction with alkyl radicals (to give an alkoxyamine), strong fluorescence is observed. Using spectrofluorimetry, the reaction of the nitroxide with polymer alkyl radicals during oxidation has been monitored. Significantly, the trapping of polymer alkyl radicals during the "induction period" at 120 degrees Celsius is observed, when it is not possible to detect changes in the polymer using either chemiluminescence or infrared spectroscopy. This highlights the sensitivity of this method and represents the direct observation of free-radical generation in polypropylene in the "induction period". TMDBIO also successfully stabilises polypropylene under thermo-oxidative conditions, which is consistent with its action as a radical trap. At elevated temperatures (150 degrees Celsius), at the end of the "induction period" when the polymer is extensively degraded, the fluorescence decreases, due to secondary oxidation of the TMDBIO

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30 citations in Scopus
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30 citations in Web of Science®

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ID Code: 1669
Item Type: Journal Article
Keywords: Profluorescent nitroxide, Radical trap, Alkoxyamine, Polypropylene, Thermal oxidation, Stabilisation, Degradation, Induction period, Fluorescence, Chemiluminescence
DOI: 10.1016/j.polymdegradstab.2005.01.030
ISSN: 0141-3910
Subjects: Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000)
Divisions: Past > QUT Faculties & Divisions > Faculty of Science and Technology
Copyright Owner: Copyright 2005 Elsevier
Copyright Statement: Reproduced in accordance with the copyright policy of the publisher.
Deposited On: 20 Jun 2005
Last Modified: 29 Feb 2012 23:12

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