Thermal oxidation of anhydride cured epoxies. I—mechanistic aspects
Thermal oxidation of anhydride cured epoxies. I—mechanistic aspects
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DOI：
10.1016/0141-3910(92)90138-u
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发表时间：
1992
影响因子：
5.9
通讯作者：
H. Huy;V. Bellenger;J. Verdu;M. París
中科院分区：
文献类型：
--
作者：
H. Huy;V. Bellenger;J. Verdu;M. París
研究了各种酸酐固化环氧树脂在 140–200°C 温度范围内、真空和空气中的热老化情况。除了轻微的后交联过程外，主要的结构变化是由于氧化造成的。可以区分两个步骤。第一种方法在 140°C 下的持续时间不超过 300 小时，单体酸酐可能由单酸悬挂基团重新形成。当该酸酐饱和时（六氢邻苯二甲酸酐），它就会放出。当它是不饱和的（甲基四氢邻苯二甲酸酐）时，它通过双键上的自由基加成结合到网络上。后一个过程导致玻璃化转变温度升高。在第一步结束时，重量损失率和 Tg 变化急剧下降，并且老化主要由聚合物规则结构单元的氧化主导。该过程本质上导致形成与第一步中形成的酸酐不同的酸酐。
The thermal ageing of various anhydride cured epoxies was studied in the temperature range 140–200°C, in vacuum and in air. Except for a slight post-crosslinking process, the main structural changes are due to oxidation. two steps can be distinguished. In the first, whose duration does not exceed 300 h at 140°C, the monomeric anhydride is reformed presumably from monoacid dangling groups. When this anhydride is saturated (hexahydrophthalic anhydride), it is evolved. When it is unsaturated (methyltetrahydrophthalic anhydride), it is bound to the network by radical additions to the double bonds. This latter process is responsible for the increase in the glass transition temperature. At the end of this first step, the rates of weight loss andTgchange decrease strongly, and the ageing becomes dominated by the oxidation of the regular structural units of the polymer. This process leads essentially to the formation of anhydrides different to those formed in the first step.