聚铝硅烷与聚碳硅烷共混先驱体制备SiC(Al)纤维  

ALUMINUM-CONTAINING SILICON CARBIDE FIBERS PREPARED FROM POLYALUMNINOCARBOSILANE AND POLYCARBOSILANE BLENDS

作　　者：赵大方[1] 李效东[1] 王海哲[1] 胡天娇[1] 郑春满[1] 王浩[1] 

机构地区：[1]国防科技大学新型陶瓷纤维及其复合材料国防科技重点实验室,长沙410073

出　　处：《高分子学报》2008年第9期831-837,共7页Acta Polymerica Sinica

摘　　要：采用聚铝碳硅烷和聚碳硅烷共混制备含铝碳化硅的先驱体,并与直接合成得到的聚铝碳硅烷进行了比较.元素分析表明,共混法能够有效控制聚铝碳硅烷中的铝含量,且共混聚铝碳硅烷先驱体Si—H键含量更高.流变性能研究表明,共混获得的聚铝碳硅烷先驱体黏流活化能从255kJ/mol降至200kJ/mol,先驱体的可纺性提高,所以原纤维的平均直径从19μm降至12μm.预氧化后聚铝碳硅烷原纤维经1800℃一步烧成可得到致密的SiC(Al)纤维;XRD研究表明,纤维中的铝起到抑制碳化硅晶粒长大的作用.The preparation of aluminum-containing silicon carbide,SiC（Al）,fibers by using polyaluminocarbosilane（PACS） and polycarbosilane（PCS） blends as precursors was investigated.The solubility parameter of PACS was determined to be 18 MPa^1/2 by dissolving PACS in solvents with different solubility parameters.It was very close to the solubility parameter of PCS（18.4 MPa^1/2）,indicating the possible compatibility of PACS and PCS.After PACS and PCS both were dissolved in xylene,a translucent yellow blend of PACS and PCS,B-PACS,was obtained by distillation.The composition and structure of B-PACS,PACS and PCS were characterized by chemical analysis,GPC and FTIR.It was found that B-PACS with desirable Al contents could be obtained by adjusting the ratio of PACS（Al content 1.25 wt%） and PCS.The Si—H bond content can be indicated by A 2100 cm^-1 /A 1250 cm^-1,where A 2100 cm^-1,A 1250 cm^-1 are the absorbance of Si—H bonds at 2100 cm^-1 and CH3 bonds at 1250 cm^-1,respectively.The FTIR results showed that the Si—H bond content of B-PACS was higher than that of PACS,while their Al contents were the same.PCS with a higher Si-H content might be responsible for the higher Si—H content of B-PACS.GPC results showed that B-PACS had a high molecular weight fraction as compared with PACS of the same Al content.The apparent activation energy of flow for B-PACS and PACS（Al content 0.6 wt%） was determined by the relationship between temperature and melt viscosity.They were 200 kJ/mol and 255 kJ/mol,respectively.The better spinnability of B-PACS was approved by spinning experiments,and finer B-PACS green fibers were obtained.The tensile strength of Si-Al-C-O fibers from PACS and B-PACS were 2.0 GPa and 2.4 GPa,respectively.The higher strength of Si-Al-C-O fibers from B-PACS might be related with the finer diameter of the green fibers and the high molecular weight fraction in B-PACS.The SiC（Al） fibers derived by curing PACS and B-PACS green fibers at 1800℃ in Ar were compact and smooth,while the SiC fib

关 键 词：聚铝碳硅烷 SIC纤维 共混 耐高温 细直径纤维 

分 类 号：TQ343.6[化学工程—化纤工业] TQ342.11