聚碳硅烷纤维氧化交联机理的研究

摘要

In order to investigate the oxidation-curing mechanism of polycarbosilane（PCS） green fibers,the products during oxidation-curing of PCS green fibers in different temperature zone were analyzed by IR,1H NMR and GC-MAS,and the oxidation-cured PCS fibers were analyzed by IR.It was found that the major reactions occurred during oxidation-curing were the oxidation of Si—H bonds and the formation of Si—OH groups.And the condensation reactions were took place between the Si—OH groups to produce Si—O—Si linkages,which were responsible for curing.When the curing temperature was over 150℃,the Si—CH3 groups were also oxidized into Si—OH,further promoting the curing process.At the same time,the side chains of PCS molecule were decomposed to small molecule during oxidation-curing,forming big molecule by condensation of the Si—OH groups.The higher the oxidation-curing temperature,the higher the molecular mass of the products.It was essential to discharge the gas during the oxidation-curing,and the decomposed products can be avoided to be adhesion on the surface of the fibers and make the fibers sticking.%对聚碳硅烷（PCS）原丝在不同氧化交联温度区间生成的逸出产物进行红外、核磁和GC-MAS分析,并结合交联丝的红外分析,推测氧化交联的机理。结果表明,PCS的氧化交联主要是其Si—H氧化生成Si—OH,后者进而彼此缩合生成Si—O—Si交联结构;氧化交联温度高于150℃时,其部分Si—CH3也开始氧化生成Si—OH并进而交联;同时,在氧化交联过程还发生PCS侧链的热裂解,所形成小分子也通过Si—OH彼此结合,形成较大分子,且其分子量随交联温度的提高而提高。因此,要及时排除氧化交联过程废气,以免逸出产物黏附在纤维表面而导致粘结。