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Type: Artigo de periódico
Title: Influence of copper-phthalocyanine on the photodegradation of polycarbonate
Author: Saron, C
Zulli, F
Giordano, M
Felisberti, MI
Abstract: Dyes and pigments are extensively used in polymer materials to confer colour-changing properties. However, these additives can significantly affect polymer stability against degradation. While the mechanism of stabilization of polymers by some pigments, such as carbon black, has been studied and is well known, the action of chromatic colorants, mainly in the sensitization of the degradation process, remains unclear. Cu-phthalocyanine dye can stabilize polymers against degradation as well as accelerate degradation in other situations. Cu-phthalocyanine incorporated into polycarbonate resulted in an acceleration of the degradation when the material was submitted to photochemical aging. The possible mechanism to explain the photodegradative behavior of PC containing Cu-phthalocyanine is based on the hypothesis that specific interactions among excited states of PC and Cu-phthalocyanine take place and enhance the formation of reactive species in polycarbonate. Excited states of Cu-phthalocyanine may abstract hydrogen atoms from methyl groups in polycarbonate, increasing the formation of free radicals P-., which are the starting points for the sequential photo-oxidation reactions that lead to the degradation of the polycarbonate. Electron transfer sensitization is also a possible mechanism: the excited state of Cu-Ph abstracts an electron from PC to form the Cu-Ph radical anion and the PC radical cation. These reactive species in the presence of oxygen can cause oxidation of the aromatic ring. (c) 2006 Elsevier Ltd. All rights reserved.
Subject: photodegradation
Country: Inglaterra
Editor: Elsevier Sci Ltd
Citation: Polymer Degradation And Stability. Elsevier Sci Ltd, v. 91, n. 12, n. 3301, n. 3311, 2006.
Rights: fechado
Identifier DOI: 10.1016/j.polymdegradstab.2006.06.004
Date Issue: 2006
Appears in Collections:Unicamp - Artigos e Outros Documentos

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