發(fā)布時(shí)間：2018-05-27 05:25

  本文選題：納米纖維 + 內(nèi)切型纖維素酶　； 參考：《南京林業(yè)大學(xué)》2015年碩士論文

【摘要】：纖維素是自然界最豐富的天然高分子材料,利用纖維素制備納米纖維是當(dāng)今研究的熱點(diǎn)。納米纖維主要利用木材、棉花、禾草類莖稈等植物,通過機(jī)械、化學(xué)、生物和人工合成等方法得到。納米纖維因具有較高的結(jié)晶度,巨大的比表面積、高純度、高楊氏模量、良好的生物可降解性和生物相容性等特點(diǎn),在生物制藥、食品加工、功能材料和造紙領(lǐng)域具有獨(dú)特的應(yīng)用價(jià)值�，F(xiàn)有制備納米纖維的方法中,分別存在產(chǎn)品得率低、設(shè)備要求高、能量消耗高、工藝復(fù)雜、制得的納米纖維粒徑和尺寸分布不合理等缺陷。因此,納米纖維的制備方法有待繼續(xù)研究。本研究利用內(nèi)切型纖維素酶(EG1)預(yù)處理全漂硫酸鹽針葉漿,再經(jīng)過超聲波協(xié)助TEMPO氧化制備納米纖維。研究中,利用氧化還原滴定和電導(dǎo)滴定監(jiān)測(cè)TEMPO氧化過程中殘余有效氯和纖維中的羧基含量;利用纖維粒度分析儀、毛細(xì)管粘度計(jì)和透射電鏡等儀器,分析制備樣品的流動(dòng)性能、尺寸分布以及纖維形貌,研究了EG1預(yù)處理對(duì)超聲波協(xié)同TEMPO氧化制備納米纖維的影響,研究結(jié)果表明:1.EG1預(yù)處理增加了超聲波協(xié)同TEMPO催化氧化后纖維中的羧基含量。超聲波協(xié)同TEMPO氧化8h后羧基含量為2.05mmol/g,EG1預(yù)處理12h、24h和48h后相同的超聲波協(xié)同TEMPO氧化條件下羧基含量分別增加到2.35mmol/g、3.03mmol/g和3.13mmol/g;與對(duì)照相比,經(jīng)EG1預(yù)處理再TEMPO氧化制備樣品的透明度增加,纖維寬度減小,流經(jīng)毛細(xì)管粘度計(jì)的時(shí)間增加。2.原料通過氫氧化鈉潤(rùn)脹或者打漿處理后再經(jīng)過EG1處理制備的納米纖維,和未經(jīng)過EG1處理的相比,羧基含量增加,透明度增加,粒徑分布向細(xì)小方向移動(dòng),流經(jīng)毛細(xì)管粘度計(jì)的時(shí)間增加。3.纖維原料隨EG1預(yù)處理時(shí)間增加得率下降,但都保持在93%以上。EG1預(yù)處理后纖維聚合度下降,EG1處理時(shí)間18h-48h后纖維素聚合度分別由原來的1478降至986-948。4.經(jīng)纖維素酶預(yù)處理24h以上的纖維原料可以通過高壓均質(zhì)機(jī)制備納米纖維,制備的納米纖維呈現(xiàn)短棒狀。
[Abstract]:Cellulose is one of the most abundant natural polymer materials. Nanofibers are obtained by mechanical, chemical, biological and synthetic methods, mainly using wood, cotton, grass stalks and other plants. Because of its high crystallinity, large specific surface area, high purity, high Young's modulus, good biodegradability and biocompatibility, nanofibers are widely used in biopharmaceutical and food processing. Functional materials and paper making have unique application value. Among the existing methods of preparing nanofibers, there are some defects such as low yield of products, high requirement of equipment, high energy consumption, complex process, unreasonable size distribution and so on. Therefore, the preparation methods of nanofibers need to be further studied. In this study, the endo-cellulase (EG1) was used to pretreat the fully bleached Kraft needle pulp, and then the nanofibers were prepared by ultrasonic assisted TEMPO oxidation. In the study, redox titration and conductometric titration were used to monitor the residual available chlorine and carboxyl content in fiber during TEMPO oxidation, and the fluidity of the prepared samples was analyzed by means of fiber particle size analyzer, capillary viscometer and transmission electron microscope. The effects of EG1 pretreatment on the synthesis of nanofibers by ultrasonic and TEMPO oxidation were studied. The results showed that the pretreatment of EG1 increased the carboxyl content of the fibers after ultrasonic and TEMPO catalytic oxidation. The carboxyl content of the sample prepared by EG1 pretreatment and TEMPO oxidation increased to 2.35 mmol / g 3.03 mmol / g and 3.13 mmol / g respectively under the same ultrasonic and TEMPO oxidation conditions after pretreatment of 2.05 mmol / g EG1 for 12 h and 48 h after 8 h of ultrasound combined with TEMPO oxidation. Compared with the control, the transparency of the samples prepared by EG1 pretreatment and TEMPO oxidation was increased. The width of the fiber decreased and the time of flowing through the capillary viscometer increased by. 2. 2. Compared with those without EG1 treatment, the content of carboxyl group increased, the transparency increased, and the particle size distribution moved to the fine direction, compared with the nanofibers prepared by sodium-hydroxide swelling or beating treatment and then treated with EG1. Increase the time of flowing through capillary viscometer. The yield of fiber raw materials decreased with the increase of EG1 pretreatment time, but the degree of fiber polymerization decreased after pretreatment with EG1 and 18h-48h from 1478 to 986-948.4 respectively. After pretreatment with cellulase for more than 24 hours, nanofibers can be prepared by high pressure homogenizer.
【學(xué)位授予單位】：南京林業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TQ352;TB383.1

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本文編號(hào)：1940631