Chemical structures and pyrolysis properties of polycarbosilane irradiated by electron beam
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摘要: 在惰性气氛下，用电子束对聚碳硅烷 (PCS) 进行辐照改性。利用傅里叶变换红外光谱分析、凝胶含量测定以及热重-气相色谱-质谱连用技术对不同剂量改性的PCS进行了分析表征，研究了辐照剂量对PCS结构与热解性能的影响。结果表明，电子束辐照作用使PCS样品中大量SiH键和CH键发生断裂，形成了以SiCSi为骨架的三维网状凝胶产物，当辐照剂量高于3 MGy时，PCS的凝胶化程度随辐照剂量的增加而明显变大。热重分析表明，电子束辐照有利于提高PCS的热稳定性，其初始失重温度和陶瓷化产率都会随辐照剂量的增加而升高，其中，经20 MGy辐照后的PCS样品的陶瓷化产率可达87%。此外，对于400 ℃预处理的PCS样品，在相同吸收剂量下，样品的凝胶质量分数、初始失重温度和最终陶瓷化产率都较未处理的高。Abstract: Polycarbosilane (PCS) was irradiated by electron beam (EB) with inert gas protection. The as-prepared specimens were characterized using IR, Gel content measurements and TG-GC-MS. The chemical structures, the pyrolysis properties and the effects of irradiation dose were investigated. The result shows that three-dimensional netlike gel products composed as SiCSi crosslinking bonds were formed in the irradiated products, and that SiH bonds and CH bonds were partly broken down in the process of irradiation. The gel content of PCS increased evidently with the irradiation dose, especially when the absorbed dose was above 3 MGy. Furthermore, the thermo-stability and ceramic yield could be improved by EB radiation and the ceramic yield of PCS irradiated under 20 MGy could be up to 87%. In addition, the gel content, the pyrolysis temperature and the ceramic yield of pre-heatment at 400 ℃ could be higher than the PCS raw material at the same absorbed dose.
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Key words:
- electron beam radiation /
- polycarbosilane /
- absorbed dose /
- chemical structure /
- pyrolysis properties
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