【摘要】 通过详细分析测定反应产物 ,研究了聚酰胺 (PA6)的热氧化降解机理 .用化学方法测定了PA6热氧化过程中几种主要基团含量的变化 ,对PA6热氧化的气相挥发产物进行收集和分析鉴定 ,还对经过氧化的PA6样品进行水解并用GC MS法对水解产物进行了分析鉴定 .在这些实验结果的基础上 ,提出了较完整的聚酰胺热氧化降解机理 .该机理包含了自由基在与酰胺基的羰基相连的亚甲基上的夺氢反应及一系列自由基加成环化和诱导断链的反应 ,能很好地解释反应产物的分析结果 .更多还原

【Abstract】 The thermo oxidative degradation of polyamide 6 (PA 6) was investigated by means of detailed analysis of the reaction products. The changes in the contents of main groups produced in PA 6 during thermo oxidation were determined by chemical methods. The volatile products of PA 6 during thermo oxidation were collected and characterized by GC MS. The hydrolysis products of oxidized PA 6 were also characterized by GC—MS.Experimental results showed that the hydroperoxide was the initial oxidation product of PA 6, and through its decomposition and further reactions, various oxidation products were formed, such as keton group and carboxylic group. From the analysis of hydrolysis products of oxidized PA 6, it was shown that a large amount of imide group was formed on the main chain. But at the same time some keton amide group was also formed on the main chain. It means that although hydrogen abstracting reaction by radicals mainly occurs at the methylene group adjacent to the nitrogen atom, it can occur at the methylene group adjacent to the carbonyl group of amide group as well. From the analysis of the volatile products, of great interest is that a lot of cyclic compounds, which had not been reported yet, were formed during thermo oxidation of PA 6.It indicates that some cyclization reactions should be included in the oxidation process of PA 6.On the basis of all the obtained experimental results a complete mechanism of PA thermo oxidative degradation was suggested. The mechanism contains the hydrogen abstracting reaction by radicals at the methylene group adjacent to nitrogen atom and at the methylene group adjacent to the carbonyl of amide group, a series of radical addition cyclization reactions, and radical induced chain scission reactions. It can well explain the results of the product analysis.更多还原