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利用低分子量聚碳硅烷(L-PCS)与乙酰丙酮铝间的热聚合反应,通过调节原料配比和反应条件,合成了不同Al含量,且具有良好可纺性的聚铝碳硅烷(PACS).研究了PACS的分子量分布和分子结构,PACS纤维空气不熔化特点并与PCS纤维进行比较.结果表明,[Al(Ac Ac)3]以-Al(Ac Ac)2悬挂和-Al(Ac Ac)-桥联两种方式接入L-PCS分子结构,PACS分子量呈双峰分布.PACS中Si—H含量和反应活性随Al含量增加而下降,氧化生成的Si—OH难以进一步形成Si—O—Si交联结构.这导致Al含量越高,凝胶点温度越高,凝胶含量随温度升高增加缓慢,同时引入多余氧.通过预氧化与高温处理相结合的方法,将不熔化纤维中氧含量控制在11 wt%以下.高温处理过程中发生自交联:Si—OH间脱水生成Si—O—Si;Si—H与Si—OH或Si—CH3脱氢生成Si—CH2—Si.
Poly aluminum carbosilane (PACS) with different Al content and good spinnability was synthesized by thermal polymerization of low molecular weight polycarbosilane (L-PCS) and aluminum acetylacetonate by adjusting the ratio of raw materials and reaction conditions. The molecular weight distribution and molecular structure of PACS, the air infusibility of PACS fibers and the comparison with PCS fibers were investigated.The results showed that [Al (Ac Ac) 3] was suspended with -Al (Ac Ac) 2 and -Al ) - bridged two ways access to the L-PCS molecular structure, PACS molecular weight showed a bimodal distribution.PACS Si-H content and reactivity decreased with increasing Al content, the formation of Si-OH oxidation is difficult to further form Si-O -Si cross-linked structure.This led to the higher Al content, the higher the gel point temperature, the gel content increases slowly with increasing temperature, while the introduction of excess oxygen.By combining pre-oxidation and high temperature treatment, the un-melted fibers The content of oxygen is controlled below 11 wt%. Self-crosslinking occurs during the high-temperature treatment: dehydration of Si-O to Si-O-Si occurs between Si-OH; Si-H and Si-OH or Si- .