微纤化纤维素及其制备技术的研究进展

微纤化纤维素(MFC)是一种主要由植物纤维制备而得的可再生高分子材料,兼具天然纤维和纳米材料的特点。近年来,有关MFC制备、改性及应用方面的研究越来越多,然而制备成本高、干燥以及再分散等仍然是MFC规模化生产所不可回避的问题。为了更全面地加深对MFC及其制备技术发展现状的认识,本文首先探讨了MFC物化特性及其命名,然后介绍了MFC机械制备方法,包括高压均质处理、微射流处理、超细研磨处理、冷冻破碎处理和高强超声处理等,并对MFC机械制备存在的问题进行了分析。本文还介绍了MFC制备过程中的预处理方法,包括纤维素酶预处理、酸-碱抽提预处理、羧甲基化预处理、TEMPO氧化预处理、高碘酸盐氧化预处理等。最后对MFC在规模化生产及干燥过程中存在的问题进行了总结。     

PBO原纤化的研究

对聚对苯撑苯并二噁唑(PBO)纤维的原纤化过程进行了研究,对制备的PBO浆粕性能进行了表征。结果表明:PBO纤维的原纤化过程经过初步处理、皮层脱落、纤维分丝3个阶段,经PFI磨打浆40 000 r后,所得浆粕产生了较好的原纤化,其原纤结晶度由60.67%下降为43.62%,直径达到纳米级,比表面积从5.18 m~2/g增大到16.2 m~2/g,保水值从13.5%提高到217.3%。     

聚乙烯醇/微纤化纤维素复合微发泡材料的制备

通过溶液浇铸法制备了聚乙烯醇(PVOH)/微纤化纤维素(MFC)复合薄膜材料,以超临界二氧化碳(scCO₂)为物理发泡剂,采用间歇式降压法制备了一系列PVOH/MFC复合微发泡材料,主要讨论了在没有水分的影响下,不同发泡温度和时间以及MFC含量对PVOH/MFC复合微发泡材料的泡孔形貌、泡孔尺寸和泡孔密度的影响;同时,也对MFC的分散性和PVOH/MFC复合材料的流变性能和热性能对发泡行为的影响进行了研究。实验结果表明,均匀分散在PVOH基体中的MFC作为异相成核剂提高了气孔成核能力,且随着MFC含量的增加,泡孔尺寸降低,泡孔密度增大;并研究了发泡温度对PVOH/MFC复合材料的发泡形貌的影响,获得最优发泡温度。     

PPTA纤维原纤化的研究进展

阐述了聚对苯二甲酰对苯二胺(PPTA)纤维的结晶结构及其原纤化的机理,综述了国内外PPTA纤维原纤化的研究进展。PPTA纤维具有皮芯结构,芯层含有高度取向的多重原纤。PPTA浆粕的制备方法主要分为机械法以及直接成型法,其关键技术在于控制纤维原纤化程度,保持纤维强度以及解决分散性能。机械法制备浆粕的方法包括磨浆设备的改进,在聚合体系中添加其他聚合物改善纤维的磨浆性能以及混合其他易原纤化纤维磨浆等。直接成型法包括沉析法和凝胶法,相对于机械法制浆,直接成型法具有工艺流程简单的优点,但是使用此方法制备浆粕,难以控制原纤的形状,纤维强度低。     

冷却方式和超声时间对Lyocell纤维原纤化程度及力学性能的影响

采用超声波震荡法对Lyocell纤维进行处理使其发生原纤化,探讨了冷却方式和超声时间对Lyocell纤维原纤化程度及其力学性能的影响。纤维的表面形态、原纤化指数与保水值结果均表明,随着冷却温度和超声时间的增加,Lyocell纤维的原纤化程度增加。超声处理后Lyocell纤维的力学性能有所下降,在实验范围内,随着冷却温度的升高,Lyocell纤维的力学性能呈下降趋势,但是波动范围较小。当超声时间≤15 min时,超声时间对Lyocell主体纤维力学性能无显著影响。     

咪喹莫特纳米结构脂质载体的可控制备及表征

采用高压均质法制备咪喹莫特纳米结构脂质载体(IMQD-NLC),分别考察表面活性剂、高压均质操作参数及药物加入量对IMQD-NLC制备的影响,并对其形貌、物相、表面Zeta电位及体外释放特性等进行了表征. 结果表明,选取S-40和Span-20复配作为表面活性剂,随着S-40含量的增大,IMQD-NLC的平均粒径和Zeta电位的绝对值逐渐减小,而PI值呈现增大趋势;高的高压均质循环次数制备的IMQD-NLC平均粒径和PI值均比较低;药量增大,粒子平均粒径和PI值增大,而Zeta电位并没有发生明显变化;平均包封率为88.3%;IMQD-NLC呈无定型状态;IMQD-NLC在pH 1的释放介质中呈现先突释后缓释,而在pH 5.5的释放介质中呈现缓慢释放.     

酮康唑纳米晶体的制备及溶出性能考察

采用高压均质法制备酮康唑纳米晶,考察稳定剂种类及浓度、酮康唑浓度、高压均质机运行压力以及均质化循环次数对粒径和多分散指数的影响。结果表明,最优制备工艺为:10%(相对主药量)的泊洛沙姆407作为稳定剂,酮康唑浓度10 mg/m L,运行压力81.6 MPa,循环次数15次。优化条件下制得的酮康唑纳米晶平均粒径为120 nm,而且研磨前后药物的晶态及化学结构没有明显改变;与原料药相比,纳米晶的溶解度、溶出速率、溶出总量均有了显著地提高。     

酮康唑纳米晶体的制备及溶出性能考察

采用高压均质法制备酮康唑纳米晶,考察稳定剂种类及浓度、酮康唑浓度、高压均质机运行压力以及均质化循环次数对粒径和多分散指数的影响。结果表明,最优制备工艺为:10%(相对主药量)的泊洛沙姆407作为稳定剂,酮康唑浓度10 mg/m L,运行压力81.6 MPa,循环次数15次。优化条件下制得的酮康唑纳米晶平均粒径为120 nm,而且研磨前后药物的晶态及化学结构没有明显改变;与原料药相比,纳米晶的溶解度、溶出速率、溶出总量均有了显著地提高。     

人造纤维

20065024湿/干处理对孔结构相关参数、保水性、回潮率的影响Kongdee A.…;Carbohydrate Polymers,2004,57(1),p.39(英)三种类型的再生纤维素纤维,常规Lyocell(CLY1),交联Lyocell(CLY2和CLY3)和微莫代尔(μCMD),经受5次二步循环处理,包括40℃水中湿处理6h和105℃干燥处理6h。然后用反向大小排斥色谱(Inverse Size Exclusion Chromatog)、保水值(W RV)、回潮率值(MRV)评估纤维孔特征产生的变化。湿/干燥处理后纤维孔隙体积减少的范围CLY1在20%、CLY213%、CLY318%、μCMD0%。同样观测到经处理后纤维保水值和回潮率值的下降。保…     

一种利用双射流法制备具有树枝状结构的芳纶微纳米纤维及其应用

本发明公开了一种利用双射流法制备具有树枝状结构的芳纶微纳米纤维及其应用.该芳纶微纳米纤维的制备方法包括如下步骤: (1) 将芳纶聚合物加入到分散溶剂中, 得到芳纶聚合物分散液; (2) 将芳纶聚合物分散液进行气喷雾化处理, 同时将分散剂进行气喷雾化处理, 然后将气喷雾化处理形成的两股射流充分混合后收集, 再分散于水中进行超声分散处理, 得到具有树枝状结构的芳纶微纳米纤维; 其中, 气喷雾化处理的条件为: 喷丝孔型为内进气孔, 外进液孔, 雾化器的孔径范围为0. 1 ～5. 0 mm, 气体压力范围为0. 1～1. 0 MPa.     

The water absorbency of hydrolyzed polyacrylonitrile-grafted cellulose fibers

The water absorbency of a bleached softwood kraft pulp, as measured by its water retention value (WRV), was increased up to 30 times by graft polymerizing polyacrylonitrile (PAN) and subsequently hydrolyzing it to sodium polyacrylate–polyacrylamide copolymer. WRV was found to be related to the initial PAN graft level rather than to the final sodium polyacrylate content, and was independent of the grafting process used. However, the ceric ion process was found superior to both the cellulose xanthate–H₂O₂ and ferrous ion–H₂O₂ redox systems in that it occasioned only a minor loss during the hydrolysis stage and the WRV was less affected by drying. The WRV remained constant as pH was lowered from 9 to 5 but dropped to the level of unmodified pulp at pH 3.5 where the sodium salt is fully converted to poly(acrylic acid). Retention of 1% aqueous NaCl was about 60% of the WRV. The swelling properties of the grafted fibers under various conditions appear to be explained by considering the grafting to act in two ways: (a) the introduction of a potentially hydrophilic component capable of generating swelling pressures and (b) the reduction in the cohesion of the fiber by the interposition of graft polymer chains in the fiber structure.     

Co-salen型仿酶系统催化漂白竹浆最优化工艺条件的研究

采用正交试验方法对竹浆Co-salen型仿酶系统催化漂白竹浆最优工艺条件及影响因素进行了研究。用白度、硬度、黏度和选择性这四个指标评价仿酶预处理的效果,并通过计算确定了各因子的影响程度及最佳因子组合。结果表明,竹浆Co-salen仿酶催化预处理较适宜的条件为:NaOH用量3.0%,H2O2用量1.0%,Co-salen用量0.03%,吡啶用量0.007%,温度90℃,时间5 h,氧压0.2 MPa,浆浓5%。     

The water retention values of never-dried alkali-treated celluloses

The extent of swelling of refined and unrefined cotton linter, viscose pulp and paper pulp treated with various concentrations of NaOH from 4 to 20% at 20°C, then washed with water and never dried was measured in terms of the water retention values (WRV). The treatment of unrefined fibers with alkali resulted in increase in WRV; the only exception was viscose pulp treated with 12 and 14% NaOH. Cotton pulp refined with 5% NaOH showed an increase in the swelling ability in water which increased with the concentration of alkali treatment, whereas for viscose and paper pulps the amount of water retained increased with alkali concentration up to 12% and 14% NaOH, respectively, then decreased with further increase in alkali concentration. For cotton and viscose pulps refined with 20% NaOH, the alkali treatment increased the affinity of fibers to water up to alkali concentrations of 16% and 12% NaOH, respectively,′ then the WRV became more or less stable after treatment with higher concentrations of NaOH. On the other hand, the paper pulp refined with 20% NaOH then treated with alkali concentrations from 10 to 20% showed decreased WRV.     

纤维状纤维素高吸附材料制备工艺的研究

本文研究对水和生理液有很好吸附和保持能力的纤维状高吸附材料的制备工艺。该材料是将纤维素纤维（棉短绒、外科用纱布）经由一种处理液进行醚化、交联等反应得到，使纤维的表面形成一层交联聚电解质，而芯层保持原有的天然结构。文中讨论了影响水吸附保持值（WRV）和生理盐水吸附保持值（SRV）的工艺因素，检测了聚电解质层中纳和铜可迁移金属平衡离子对血浆吸附性能的影响。结果表明，采用本工艺使改性棉短绒的WRV和SRV分别为未变性时的12倍和6倍，变性纱布则分别为未改性时的6倍和4．7倍。     

Hot Alkali Refining of Cellulosic Pulps in the Presence of Sodium Sulfide

Cotton linter pulp and paper pulp were subjected to hot refining with potassium and sodium hydroxide in the presence of sodium sulfide at concentrations of 5% and 20%. The resulting changes in their chemical, physical, and submicroscopic properties as well as their mercerization depth were studied. The addition of sodium sulfide during hot sodium or potassium hydroxide refining of the pulps resulted in a small increase in α-cellulose content of the cotton linters. Remarkable increase was observed in the case of the paper pulp as well as in the resulting decrystallization, and it increased the heterogeneity of the macromolecular structure of both pulps. This led to an increase in the swelling ability of the fibers as revealed from the results of water retention value (WRV), liquor retention value (LRV), and sodium hydroxide retention value (NaOH RV). The addition of sodium sulfide to sodium or potassium hydroxide during hot refining of the cotton linters or to sodium hydroxide during refining of the paper pulp led to the reduction in the degree of polymerization and to improvement in the reactivity towards xanthation. This was in contrast to the results of the alkali refining of the paper pulp with a mixture of potassium hydroxide-sodium sulfide in which the degree of polymerization was increased and the reactivity towards xanthation was decreased. The mercerization depth of the hot refined pulps was also investigated using FUR 1650 spectrophotometer absorption method. The cotton linters refined with a mixture of 5% sodium hydroxide-sodium sulfide possessed a higher degree of chemical purity and a good open and accessible fine structure and at the same time were characterized with a higher degree of polymerization suitable for use as a starting refined pulp for the manufacture of paper documents.     

超声波技术制备微晶壳聚糖

利用天然高分子壳聚糖为原料制备了微晶壳聚糖,以特性粘度为主要性能指标,研究了壳聚糖浓度、降解时间、NaOH的浓度等对壳聚糖特性粘度的影响,经单因素试验得出了最优工艺条件为:壳聚糖浓度为1.2%,降解时间为4 h、NaOH的浓度为5%;同时,研究了微晶壳聚糖的保水值(WRV),与壳聚糖相比,微晶壳聚糖的保水值提高近一倍。     

高纯耐热耐碱木聚糖酶预处理对杨木KP浆漂白特性的影响

研究了耐热耐碱木聚糖酶X对杨木硫酸盐浆预处理的选择性及其对无元素氯(ECF)漂白特性的影响。结果表明:该木聚糖酶预处理具有高的助漂选择性,预处理对纸浆的得率及黏度影响不大;该木聚糖酶对温度及pH的适应范围较广,在温度为75～80℃、pH 8.0～9.5范围内都可以发挥有效的助漂作用,尤其在温度80℃、pH 8.0、酶用量2 IU/g的条件下更能发挥酶效;耐热耐碱木聚糖酶X预处理可减少漂白ClO2用量,当达到对照浆相同白度(90%ISO)时可减少D0段26%～27%的ClO2用量(相当于总用氯量的16%)。     

漆酶和木聚糖酶预处理对麦草浆漂白性能的影响

生物漂白主要目的在于通过对纸浆预处理,减少后续漂白时漂剂用量,降低漂白废水对环境污染,同时改善纸浆性能。通过漆酶/木聚糖酶体系(LXS)和重组木聚糖酶(X)对麦草浆预处理,比较它们对浆料脱木素能力和漂白性能的影响。结果表明:麦草浆经过两种酶预处理后,都能降低浆料卡伯值,而漆酶处理后降低的幅度更大,与原浆和木聚糖酶处理浆相比分别降低32.64%和6.47%,但是在木聚糖酶处理液中能检测到更多的还原糖;两种酶处理浆在后续漂白中漂白至与对照浆相近白度时均能节省50%漂剂用量,且能改善浆料物理强度;比较两种酶对浆料漂白性能的影响,则是在相同漂剂用量时木聚糖酶漂白浆的白度稍高,而浆料得率和强度稍低;两种酶处理浆料的纤维素结晶度测定表明酶处理前后浆料的纤维素的结晶结构没有明显的变化,而且纤维素的结晶度都有不同程度的提高。通过扫描电镜观察以及X射线光电子能谱(XPS)分析,从理论上说明两者脱木素的差异。     

超临界CO_2萃取脱除毛竹木质素的研究

研究了在CO2的超临界流体中,以二氧杂环己烷/水为夹带剂,毛竹木质素的脱除规律。采用4因素3水平的正交试验,对脱木质素效率、纸浆得率、残渣中Klason木质素含量及综纤维素含量的影响因素进行了分析。结果表明,温度是影响脱木质素效率的主要因素,其次是压力,反应时间和夹带剂体积分数对木质素溶出效率的影响相对较小。温度越高,萃取液中Klason木质素含量越高,但其综纤维素含量越低,纸浆得率也越低。在180℃、20 MPa下,采用95%（体积分数）二氧六环水溶液作夹带剂,萃取1 h,可得到较高的脱木质素率,达到84.18%。对不同温度下超临界萃取液的GC-MS分析表明,总离子流图流出峰中存在具有乙氧基的直链或支链以及含氧五元环结构的醇、醛、酮、酸和酯类化合物,也存在如香草醛、对羟基苯甲醛等木质素的基本结构单元。萃取液的组成受温度的影响很大,在较低温度（160℃）下,没有糠醛及香豆酮等的产生,而在较高温度（200℃）下,香豆酮质量分数接近15%,糠醛质量分数可达42%以上。     

细小纤维表面化学特性研究(Ⅰ)——湿部pH值对细小纤维性能的影响

对漂白桉木KP浆的细小纤维及长纤维打浆后产生的细小纤维在不同pH值条件下的电荷需求量、叩解度和保水值变化情况进行了研究,结果如下:pH值影响细小纤维的表面电荷密度,并对细小纤维的叩解度和保水值有非常大的影响。pH值从4升高到10,原生细小纤维(P₂₀₀)、打浆产生的细小纤维(P'₂₀₀)的阳离子需求量分别由0.033和0.050 meq/g增大到0.060和0.110 meq/g;P₂₀₀和P'₂₀₀的阴离子需求量最大值分别为0.014和0.01 meq/g;pH值在4～10范围P₂₀₀和P'₂₀₀呈"净负电荷性",在中性条件下,P₂₀₀和P'₂₀₀的胶体滴定比率(CTR值)最大值分别约为0.4和0.2。pH值对叩解度的影响P₂₀₀大于P'₂₀₀,pH值对保水值的影响P₂₀₀小于P'₂₀₀,P'₂₀₀有较大的初始叩解度和较高的初始保水值。