退役硅橡胶复合绝缘子热降解行为的研究

The thermal degradation of waste silicone rubber composite insulators

采用在线热裂解-气质联用(Py-GC-MS)技术对废旧硅橡胶复合绝缘子在不同温度下(300℃,400℃,500℃,600℃)的热降解行为进行了研究,并通过质谱中裂解产物的碎片离子信息对其裂解机理进行探究。结果表明:硅橡胶裂解产物为一系列二甲基硅氧烷环体及少量的链状硅氧烷,主要环体为六甲基环三硅氧烷(D3)、八甲基环四硅氧烷(D4)及环五硅氧烷直至环九硅氧烷;较高的裂解温度下,大环基本裂解完全,仅剩小环裂解产物。因此用热裂解处理废旧硅橡胶时,温度需要达到500℃及以上才会有较好的效果。

The thermal degradation of waste silicone rubber composite insulators at different temperatures （300 ℃, 400 ℃ , 500 ℃ , 600 ℃ ） was studied using pyrolysis gas chromatography - mass spectrometry （ Py-GC - MS）. Based on the observed fragment ions, we propose a probable pyrolysis mechanism for silicone rubber. A series of cyclomethicones and chain siloxanes were detected in the pyrolysis products at different temperatures. The main cy- clomethicones are hexamethyleyclotrisiloxane （ D3 ） , octamethylcyclotetrasiloxane （ D4 ） along with decamethylcyclo- pentasiloxane up to octamethylcyclohexasiloxane. The proportion of the different cyclomethicones varies with tem- perature. With increasing cracking temperature, the larger cyclomethicone molecules are no longer observed and the proportion of small cyclomethicone molecules is increased. Therefore, the optimum degradation results are obtained by thermally cracking waste silicone rubber composite insulators at temperatures above 500 ℃.