木质素熔融纺丝制备碳纤维研究

发布时间：2018-04-13 16:16

本文选题：木质素 + 提纯与改性　；参考：《天津工业大学》2017年硕士论文

【摘要】：木质素是植物中含量最高的芳香族高分子,目前主要作为利用纤维素的副产物,直接排放不仅造成环境污染,还是一种资源的浪费。近年来,工业木质素被加工成分散剂、水泥减水剂、钻井液降黏剂等低价值产品,高值化应用较少。工业木质素价格低廉,可再生可生物降解并且碳含量高,用其制备碳纤维既能提高木质素的利用价值,还能降低碳纤维的生产成本。本文考察了对6种工业木质素原料的结构和性能,从中筛选出适宜制备碳纤维的木质素原料;经提纯与改性后,采用熔融纺丝和熔喷法制备了木质素基纤维,再通过固化、预氧化和碳化得到碳纤维。探讨了木质素基纤维原丝的制备、固化、预氧化和碳化工艺参数。采用红外和热重表征工业木质素的链结构和热稳定性,结果表明,6种工业木质素的分离提取过程未破坏原有木质素的核心骨架结构,其中,松木硫酸盐木质素(KL)和马尾松碱木质素(AL-2)的热稳定性较好。考察工业木质素的溶解性,结果表明,松木质素磺酸盐类没有合适的提纯溶剂,麦草和杨木混合的碱木质素(AL-1)提纯的最高产率仅有20%,KL和AL-2采用酸性水溶液提纯,提纯产率达95%以上,故选择提纯效率较高的KL和AL-2进行制备碳纤维的深入研究。采用Py-GC/MS及HAKEE流变仪表征改性前后的木质素,结果表明,改性前的木质素以愈创木型木质素衍生物为主,而改性后的木质素以苯酚衍生物结构为主;改性木质素的黏度对温度较敏感,并且在同一测试条件下,黏度主要由其低分子量所占的比例和木质素原料的分子量决定。采用流变仪模拟木质素的熔融纺丝和熔喷,获得不同热处理的改性木质素的可纺温度范围以及改性KL的最佳熔喷温度。最后,熔喷法制备的木质素基纤维的直径小于熔融纺丝得到的木质素基纤维;采用热性能、元素分析等表征手段考察了纤维固化、预氧化和碳化的工艺参数,并得到最佳工艺条件,在此条件下制备出碳含量达95.15%的木质素基碳纤维毡。
[Abstract]:Lignin is the most abundant aromatic polymer in plants. At present, lignin is mainly used as a by-product of cellulose utilization. Direct emission not only causes environmental pollution, but also a waste of resources.In recent years, industrial lignin has been processed into low value products such as dispersant, cement water reducing agent, drilling fluid viscosity reducer and so on.Industrial lignin has the advantages of low price, renewable biodegradability and high carbon content. Using it to prepare carbon fiber can not only improve the utilization value of lignin, but also reduce the production cost of carbon fiber.In this paper, the structure and properties of six kinds of industrial lignin raw materials were investigated, and the lignin materials suitable for carbon fiber preparation were screened out. After purification and modification, lignin based fibers were prepared by melt spinning and melt blown method, and then solidified.Carbon fiber can be obtained by preoxidation and carbonization.The preparation, curing, preoxidation and carbonization process parameters of lignin-based fiber precursor were discussed.The chain structure and thermal stability of industrial lignin were characterized by IR and TGA. The results showed that the separation and extraction of six kinds of industrial lignin did not destroy the core skeleton structure of the original lignin.The thermal stability of pine KL and Masson pine alkali-lignin (AL-2) is better than that of KL (KL) and AL-2 (Pinus massoniana).The solubility of industrial lignin was investigated. The results showed that there was no suitable solvent for the purification of pine lignin sulfonates. The highest yield of alkaline lignin (AL-1) from wheat straw and poplar was only 20% KL and AL-2 were purified by acid aqueous solution.The yield of carbon fiber was over 95%, so KL and AL-2, which had higher purification efficiency, were selected to study the preparation of carbon fiber.Py-GC/MS and HAKEE rheometer were used to characterize the lignin before and after modification. The results showed that the lignin before modification was mainly guaiacular lignin derivative, while the modified lignin was phenol derivative structure.The viscosity of modified lignin is sensitive to temperature, and the viscosity is mainly determined by the proportion of low molecular weight of modified lignin and the molecular weight of lignin raw material under the same test conditions.The melt spinning and melt blowing of lignin were simulated by rheometer. The spinning temperature range of modified lignin with different heat treatment and the optimum melting temperature of modified KL were obtained.Finally, the diameter of lignin based fibers prepared by melt-blown method was smaller than that of lignin based fibers prepared by melt spinning, and the technological parameters of curing, preoxidation and carbonization of the fibers were investigated by means of thermal properties and elemental analysis.Under the optimum conditions, the lignin based carbon fiber felt with a carbon content of 95.15% was prepared.
【学位授予单位】：天津工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ342.742

【参考文献】