Mechanism of the temperature-dependent degradation of polyamide 66 films exposed to water

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• 作者：Elsa Silva Gonç ; alves ; Lars Poulsen ; Peter R. Ogilby
• 关键词：FTIR ; Oxygen ; Polyamide 66 ; Water sorption ; Radicals
• 刊名：Polymer Degradation and Stability
• 出版年：2007
• 出版时间：November 2007
• 年：2007
• 卷：92
• 期：11
• 页码：1977-1985
• 全文大小：271 K

文摘

Experiments were performed to elucidate the degradation mechanism of hot-pressed polyamide 66 upon exposure to water. For films exposed to water over the temperature range 25 °C–90 °C, degradation was monitored using FTIR and solid-state ¹³C NMR spectroscopies. The data are consistent with a mechanism in which (1) a radical is formed on the methylene carbon adjacent to the amide nitrogen, (2) this radical reacts with oxygen to form a hydroperoxide, and (3) the hydroperoxide decomposes to form an imide or a hydroxylated amide, both of which may cleave leading to chain scission. Water appears to facilitate degradation by increasing the flexibility of the polymer matrix through swelling rather than acting as a reactive species, at least at the early stages of the process. An apparent activation energy of 15 ± 2 kJ/mol is observed for the early stages of degradation, suggesting that segmental motions in the polymer associated with water and oxygen sorption or inter-chain radical reactions are indeed key components of the degradation process.