The role of hindered piperidine (HALS) compounds for the stabilization of polypropylene against oxidation reactions caused by ozone and oxidative products formed during photolysis of ozone |
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| Authors: | J Lucki J F Rabek B Rånby Y Watanabe |
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| Affiliation: | 1. Department of Polymer Technology, Royal Institute of Technology, Stockholm, Sweden;2. Research Institute for Polymers and Textiles, Tsukubo, Japan |
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| Abstract: | The role of hindered piperidine (HALS) photostabilizers for the photostabilization of polypropylene films against oxidative reactions caused by ozone and oxidative species formed during photolysis of ozone under UV irradiation (i.e., atomic oxygen and singlet oxygen) has been investigated and discussed. It has been found that ozonization and/or photoozonization of 2,2,6,6-tetramethyl-piperidine (I) and piperidinoxy radical (2,2,6,6-tetramethylpiperidino-1-oxy) (II) gives a high yield (91–98%) 2,6-dimethyl-2-hydroxy-6-nitro-heptane. Ozonization and/or photoozonization of HALS probably occur by a similar mechanism as reported for (I) and (II). HALS photostabilizer reacts with ozone and/or photolysis products of ozone (atomic oxygen and/or singlet oxygen) and loses its function in the photostabilization process. For that reason protection of polypropylene against photooxidative degradation and photoozonization is of great commercial importance. |
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