Mechanisms of antioxidant action: the role of O-macroalkyl hydroxylamines in the photoantioxidant mechanism of HALS
Mechanisms of antioxidant action: the role of O-macroalkyl hydroxylamines in the photoantioxidant mechanism of HALS
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DOI：
10.1016/0141-3910(96)00025-0
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发表时间：
1996-06
影响因子：
5.9
通讯作者：
Xing Hu;G. Scott
中科院分区：
文献类型：
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作者：
Xing Hu;G. Scott
以2，2，6，6-四甲基-4-羟基哌啶氧基(>；NO·)与乙丙橡胶(EPR)和聚丙烯(PP)为原料，在过氧化二烷基催化剂存在下反应合成了O-大烷基羟胺(>；NOP)。在最佳条件下，70%的>；NOP是基于添加到聚合物中的>；NO·形成的，其余的是游离羟胺(>；noh)。>；NOEPR和>；NOPP分别是EPR和PP的有效光抗氧化剂。在彻底提取薄膜以去除>；Noh后，部分活性仍按比例与共价结合到聚合物上的[>；NO]成比例。结果表明，在没有明显诱导期的情况下，>；NOPS从光氧化开始就转化为>；NO·，可能是通过中间体>；NOH。然而，在紫外光照射下，大多数>；NO以大分子>；NOP的形式存在于聚合物中，因为它能抵抗反复的溶剂提取/光氧化循环。讨论了由>；NOP再生~gt；NO·的一些可能机制。
O-Macroalkyl hydroxylamines (>NOP) have been synthesised by reaction of 2,2,6,6-tetramethyl-4-hydroxy piperidinoxyl (>NO•) with ethylene-propylene rubber (EPR) and polypropylene (PP) by reactive processing in the presence of a dialkyl peroxides. Under optimal conditions, 70% of >NOP was formed based on >NO• added to the polymer, the remainder being free hydroxylamine (>NOH). >NOEPR and >NOPP are effective photoantioxidants for EPR and PP respectively. After exhaustive extraction of the films to remove >NOH, a proportion of the activity remained pro-rata to the [>NO ] covalently bound to the polymer. It is concluded that >NOPs are converted to >NO• from the commencement of photooxidation without a significant induction period, possibly through the intermediate >NOH. However, most of the >NO is present in the polymers as macromolecular >NOP during UV exposure since it is resistant to repeated cycles of solvent extraction/photooxidation. Some possible mechanisms for the regeneration of >NO• from >NOP are considered.