EFFECTS OF WEAK LINKAGES ON THE THERMAL AND OXIDATIVE-DEGRADATION OF POLY(METHYL METHACRYLATES)
EFFECTS OF WEAK LINKAGES ON THE THERMAL AND OXIDATIVE-DEGRADATION OF POLY(METHYL METHACRYLATES)
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DOI：
10.1021/ma00162a010
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发表时间：
1986-08-01
期刊：
影响因子：
5.5
通讯作者：
MASUDA, E
中科院分区：
文献类型：
--
作者：
KASHIWAGI, T;INABA, A;MASUDA, E
使用各种特殊聚合样品，通过热重分析法研究了聚甲基丙烯酸甲酯（PMMA）在氮气和空气气氛中的热降解和氧化降解机制。采用自由基法聚合的PMMA的热降解过程分为三个失重步骤：最不稳定的步骤是由头对头键的断裂引发的，第二个步骤是由亚乙烯基末端引发的链端断裂，最稳定的步骤是聚合物链内的随机断裂。以偶氮二异丁腈和过氧化苯甲酰为引发剂，自由基法聚合的PMMA的热降解和氧化降解没有显着差异。气相氧捕获头对头连接处断链产生的自由基。在空气中从该步骤没有观察到重量损失。类似地，氧捕获末端引发产生的自由基，但它不如头对头连接的情况那么有效。讨论了头对头连接处断裂引发的自由基末端引发和氧化终止的可能机制。
The thermal and oxidative degradation mechanisms of poly (methyl methacrylate)(PMMA) were studied in atmospheres of nitrogen and air by thermogravimetry using various specially polymerized samples. Thermal degradation of PMMA polymerized with a free radical method proceeds in three steps of weight loss: the least stable step is initiated by scissions of head-to-head linkages, the second step by scissions at the chain-end initiation from vinylidene ends, and the most stable step by random scission within the polymer chain. There are no significant differences seen in the thermal or oxidative degradation ofPMMA polymerized with the free radical method between azobis (isobutyronitrile) and benzoyl peroxide as the initiators. Gas-phase oxygen traps radicals resultingfrom chain scissions at head-to-head linkages. No weight loss is observed from this step in air. Similarly, oxygen traps radicals generated by end initiation, but it is not as effective as for the case of head-to-head linkages. Possible mechanisms for end initiation and oxidative termination of radicals initiated from scission at the head-to-head linkages are discussed.