壳聚糖衍生物处理碳纳米管改性聚丙烯腈基碳纤维

MODIFICATION OF POLYACRYLONITRILE-BASED CARBON FIBER WITH CARBON NANOTUBES TREATED BY CHITOSAN DERIVATIVES

自制了邻苯二甲酰化壳聚糖、萘甲酰化壳聚糖、羧甲基化壳聚糖等3种壳聚糖衍生物对多壁碳纳米管(MWNTs)进行表面处理,发现邻苯二甲酰化壳聚糖(PhthCS)能有效提高MWNTs在极性6～10范围溶剂中的分散性及稳定性,并考察了PhthCS的分子量及浓度对MWNTs的分散性及稳定性的影响;通过微观形貌和元素分析,发现MWNTs部分表面包覆了一层厚度约为5～10 nm的包覆膜.经凝胶纺丝工艺制备了PhthCS-MWNTs/聚丙烯腈复合原丝,经预氧化、炭化制备了复合碳纤维,SEM结果表明PhthCS-MWNTs在复合原丝和复合碳纤维中分散均匀,良好取向;PhthCS-MWNTs对复合原丝和复合碳纤维的力学性能具有明显的改善作用,当PhthCS-MWNTs含量为0.5%时,复合碳纤维的拉伸强度提高了19.8%;增加PhthCS-MWNTs用量对复合碳纤维的拉伸模量具有显著提高,当PhthCS-MWNTs含量为3%时,复合碳纤维的杨氏模量从6.24 GPa提高到了13.86 GPa,增大了122%.

A polyacrylonitrile-based carbon fiber modified with multi-walled carbon nanotubes（MWNTs） was prepared in this paper.Three chitosan derivatives,phthaloyl chitosan（PhthCS）,naphthoyl chitosan and carboxymethyl chitosan,were used for surface treatments of MWNTs in order to improve their dispersion and stability.Acidizing MWNTs and original MWNTs were also used for comparison with the MWNTs treated with chitosan derivatives.Results indicate that the dispersion and stability of PhthCS-MWNTs were improved significantly in those solvents possessed of polarity from 6 to 10.The effects of molecular weight and concentration of PhthCS on the dispersion stability of the MWNTs were evaluated.Results of transmission electron microscopy and element analysis of the MWNTs reveal that part of MWNTs＇ surfaces are coated by a layer of PhthCS with the thickness of 5 ~ 10 nm,which changes the surface properties and dispersion stability of the MWNTs.A composite PhthCS-MWNTs/carbon fiber was fabricated through gel-spinning,preoxidation,low-temperature carbonization and high-temperature carbonization.SEM results exhibit that the PhthCS-MWNTs dispersed uniformly and oriented preferentially within the composite fibers,which led to improved mechanical properties of the composite carbon fiber.The tensile strength of the composite carbon fiber with 0.5% PhthCS-MWNTs is 19.8% higher than that of the carbon fiber without MWNTs.And the Young＇s modulus of the composite carbon fiber containing 3% PhthCS-MWNTs is 13.86 GPa,which is 122% higher than that of the carbon fiber without MWNTs.However,the elongation at break of the composite carbon fiber changed scarcely by adding the PhthCS-MWNTs.