本文選題：木質(zhì)素 + 提純與改性��； 參考：《天津工業(yè)大學(xué)》2017年碩士論文

【摘要】：木質(zhì)素是植物中含量最高的芳香族高分子,目前主要作為利用纖維素的副產(chǎn)物,直接排放不僅造成環(huán)境污染,還是一種資源的浪費(fèi)。近年來,工業(yè)木質(zhì)素被加工成分散劑、水泥減水劑、鉆井液降黏劑等低價(jià)值產(chǎn)品,高值化應(yīng)用較少。工業(yè)木質(zhì)素價(jià)格低廉,可再生可生物降解并且碳含量高,用其制備碳纖維既能提高木質(zhì)素的利用價(jià)值,還能降低碳纖維的生產(chǎn)成本。本文考察了對(duì)6種工業(yè)木質(zhì)素原料的結(jié)構(gòu)和性能,從中篩選出適宜制備碳纖維的木質(zhì)素原料;經(jīng)提純與改性后,采用熔融紡絲和熔噴法制備了木質(zhì)素基纖維,再通過固化、預(yù)氧化和碳化得到碳纖維。探討了木質(zhì)素基纖維原絲的制備、固化、預(yù)氧化和碳化工藝參數(shù)。采用紅外和熱重表征工業(yè)木質(zhì)素的鏈結(jié)構(gòu)和熱穩(wěn)定性,結(jié)果表明,6種工業(yè)木質(zhì)素的分離提取過程未破壞原有木質(zhì)素的核心骨架結(jié)構(gòu),其中,松木硫酸鹽木質(zhì)素(KL)和馬尾松堿木質(zhì)素(AL-2)的熱穩(wěn)定性較好。考察工業(yè)木質(zhì)素的溶解性,結(jié)果表明,松木質(zhì)素磺酸鹽類沒有合適的提純?nèi)軇?麥草和楊木混合的堿木質(zhì)素(AL-1)提純的最高產(chǎn)率僅有20%,KL和AL-2采用酸性水溶液提純,提純產(chǎn)率達(dá)95%以上,故選擇提純效率較高的KL和AL-2進(jìn)行制備碳纖維的深入研究。采用Py-GC/MS及HAKEE流變儀表征改性前后的木質(zhì)素,結(jié)果表明,改性前的木質(zhì)素以愈創(chuàng)木型木質(zhì)素衍生物為主,而改性后的木質(zhì)素以苯酚衍生物結(jié)構(gòu)為主;改性木質(zhì)素的黏度對(duì)溫度較敏感,并且在同一測(cè)試條件下,黏度主要由其低分子量所占的比例和木質(zhì)素原料的分子量決定。采用流變儀模擬木質(zhì)素的熔融紡絲和熔噴,獲得不同熱處理的改性木質(zhì)素的可紡溫度范圍以及改性KL的最佳熔噴溫度。最后,熔噴法制備的木質(zhì)素基纖維的直徑小于熔融紡絲得到的木質(zhì)素基纖維;采用熱性能、元素分析等表征手段考察了纖維固化、預(yù)氧化和碳化的工藝參數(shù),并得到最佳工藝條件,在此條件下制備出碳含量達(dá)95.15%的木質(zhì)素基碳纖維氈。
[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.
【學(xué)位授予單位】：天津工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TQ342.742

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