木质素基取向纳米碳纤维功能材料制备及性能表征

发布时间：2018-08-04 11:22

【摘要】：木质素是自然界中丰富的可再生有机资源,广泛存在于植物纤维原料中,在自然界中蕴藏量仅次于纤维素,是世界上第二位最丰富的有机物。其含碳量较高,因此可作为碳纤维的原料进行利用。本论文的研究内容和成果包括以下三部分:(1)以碱性木质素为主要原料,与聚环氧乙烷(又名聚氧化乙烯,PEO)混合溶于甲酸中,通过静电纺丝的方法来制备木质素基复合纳米纤维并通过预氧化和碳化处理得到木质素基碳化纤维。讨论了溶液浓度,接收距离,正极电压和滚筒转速对纺丝纤维形态的影响。结果表明,质量分数为20%为最佳纺丝浓度。最佳纺丝工艺参数为负电压为-2kV,正电压为20kV,接收距离为15cm,滚筒转速为1000r/min。并对纤维及原料进行了傅里叶变换红外光谱仪分析(FTIR)和热分析(TG和DSC),表明木质素与PEO之间形成了氢键作用,纤维原丝中木质素和PEO两者没有发生相分离。(2)为了防止碳化过程中纤维发生熔融而失去纤维形态,需要对复合纤维进行预氧化处理。实验试探了预氧化过程中空气含量、升温速率和温度对纤维的影响。结果表明,本实验最佳预氧化工艺为,室温以2℃/min的速率升温至300℃,保温120min。之后,对复合纤维进行了碳化处理在升温速率为5℃/min条件下,分别在600℃,700℃,800℃和900℃保温300min进行碳化处理。使用扫描电子显微镜(SEM)、热重分析(TG)、元素分析仪、X射线衍射仪(XRD)、拉曼光谱仪(Raman)、电导率测试和电化学测试对预氧化纤维和碳化纤维的微观形貌、碳元素含量、纤维晶型、碳层有序度以及纤维导电性进行了表征。结果表明,本实验所采用的温度范围内,碳化纤维均为乱层石墨结构,碳结构均为无定型碳,随着温度的增高,C含量增高,导电性变大。900℃碳化纤维的电导率为4.316S/cm,比电容为35F/g。(3)以碱性木质素为主要原料,与PEO和乙酸镍(C_4H_6NiO_2·4H_2O)混合溶于甲酸中,通过静电纺丝的方法来制备复合纳米纤维并通过预氧化和碳化处理得到木质素基功能化碳纤维。在空气中以2℃/min的升温速率在300℃下保温120min的条件下进行预氧化,在氮气氛围中5℃/min,800℃保温300min的条件下进行碳化处理,使用SEM、TG、DSC、EDS、XRD、Raman、表面电阻分析仪和电化学工作站对碳化纤维的微观形貌、纤维晶型、碳层有序度、导电性能进行表征。结果表明:碳化之后纤维表面出现了颗粒状物质,Ni元素主要分布在纤维表面,碳化纤维均为乱层石墨结构,碳结构均为无定型碳,碳化之后乙酸镍转化为了NiO和Ni,与不含Ni的碳化纤维相比,纤维的电导率变大为3.698S/cm,比电容也增大为59F/g。
[Abstract]:Lignin is a rich renewable organic resource in nature. Lignin is the second most abundant organic substance in the world. Because of its high carbon content, it can be used as the raw material of carbon fiber. The research contents and achievements of this thesis include the following three parts: (1) the basic lignin was mixed with polyethylene oxide (PEO) and dissolved in formic acid. Lignin based composite nanofibers were prepared by electrospinning and the lignin based carbonated fibers were obtained by preoxidation and carbonization. The effects of solution concentration, receiving distance, positive voltage and rotary speed on fiber morphology were discussed. The results showed that the optimum spinning concentration was 20%. The optimum spinning parameters are negative voltage of -2kV, positive voltage of 20kV, receiving distance of 15cm, rotary speed of 1000r / min. The fiber and raw materials were analyzed by Fourier transform infrared spectroscopy (FTIR) and thermal analysis (TG and DSC), showed that the hydrogen bond between lignin and PEO was formed. Lignin and PEO were not separated from each other. (2) in order to prevent the fiber from melting and lose the fiber morphology during carbonization, the composite fiber should be preoxidized. The effects of air content, heating rate and temperature on fiber during preoxidation were investigated. The results show that the optimum preoxidation process is that the temperature is raised to 300 鈩，

本文编号：2163824