纤维素氨基甲酸酯法制备纤维素海绵

海绵因具有蓬松度好、质地柔软、吸水性好等优点而得以广泛应用。但目前市面上的聚氨酯海绵,不仅原料紧缺,制备过程有污染物产生,而且废弃后难降解,会产生二次污染。为开发可自然降解的纤维素海绵无污染制备工艺,研究了采用纤维素氨基甲酸酯法制备纤维素海绵的工艺。结果表明：由纤维素氨基甲酸酯的氢氧化钠溶液捏合而成的海绵混合体经蒸煮,纤维素再生,成孔剂溶于水中而留下空隙,所得纤维素海绵孔径均一,表面光滑平整,具有较好的柔韧性和黏弹性,完全具有普通聚氨酯海绵的基本特征。     

纤维素-丝素复合膜的制备与表征

通过NaOH/尿素/硫脲/水新型溶剂溶解原生木浆纤维素得到纤维素溶液,并与丝素溶液混合制备纤维素-丝素复合膜.利用扫描电镜、红外光谱、X-射线衍射对复合材料的结构进行表征.SEM结果表明复合材料表面粗糙,比表面积较大,可以作为潜在的生物医用材料.IR和X-衍射结果表明再生纤维素与丝素分子之间存在着强烈的氢键作用,且二者相容性较好.     

纤维素氨基甲酸酯的生产工艺研究

探讨了新型纤维素纤维原料纤维素氨基甲酸酯的生产工艺,指出当纤维素浆粕活化用氢氧化钠溶液质量分数为14％～16％,活化温度40～50℃,活化时间为30～40min,尿素与纤维素的质量比(2:1)～ (3:1),反应时间为2-3 h时,纤维素氨基甲酸酯可在氧氧化钠溶液中形成良好的稳定溶液,其过滤性好, 可直接用于纺丝。     

Preparation and characterization of dense cellulose film for membrane application

Regenerated cellulose films were prepared with environmentally friendly process by utilized N‐methylmorpholine‐N‐oxide (NMMO)‐Cellulose system. To prepare a dense cellulose film for membrane application, some parameter process which influence porous forming such as cellulose DP, cellulose concentration, addition NMMO in coagulation bath, coagulation bath temperature, and drying condition were investigated. We resumed that the porosity and pore size of cellulose membrane decrease with lower cellulose DP, higher cellulose concentration, addition of NMMO in coagulation bath, applying room temperature in coagulation bath and drying, and applying vacuum on drying process resulted in membranes with porosity in range of 24–41% and pore size 13.4–20.2 nm. The main factor for controlling porosity and pore size of dense cellulose membrane was coagulation process condition especially addition of NMMO into coagulation bath. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

纤维素氨基甲酸酯溶液的流变性能

研究了纤维素氨基甲酸酯溶液的流变性能,并与粘胶溶液进行了比较。结果表明,纤维素氨基甲酸酯溶液为切力变稀型流体,与粘胶溶液相比,非牛顿指数小,结构粘度指数大,可纺性差;随温度的升高,表观粘度降低．到25℃以后发生凝固,粘度急剧增大;随着纤维素氨基甲酸酯溶液浓度的增加,表观粘度显著上升,曲线呈指数关系,得到了表观粘度与浓度的经验公式。     

高吸附量纤维素膜的制备及其对Pb2+的吸附性能

以纤维素为原料,氢氧化钠、尿素、硫脲为溶剂体系制备纤维素膜,研究凝固浴的种类、H2SO4体积分数、凝固温度和凝固时间对纤维素膜吸附Pb~(2+)的影响。采用准二级动力学模型研究吸附速率的快慢;采用SEM、比表面积和平均孔径、FTIR和XRD分析纤维素膜的结构和吸附机理;采用TG对纤维素膜的热性能进行分析。结果表明,以体积分数为7%的H2SO4为凝固浴、凝固温度为40℃、凝固时间为120min时,纤维素膜对Pb~(2+)的吸附量达到最大,为343.0mg/g。纤维素膜吸附Pb~(2+)符合准二级动力学模型。纤维素膜由表面致密变为含有孔洞的结构,吸附Pb~(2+)后孔洞被填满,纤维素膜中的C=O键和N—H键与Pb~(2+)产生螯合作用。纤维素膜中部分纤维素结晶型由Ⅰ型转变为Ⅱ型,结晶度降低;纤维素膜的热稳定性高于纤维素。     

尿素增溶纤维素氨基甲酸酯的可纺性研究

探索了尿素对纤维素氨基甲酸酯(CC)/氢氧化钠溶液(CC溶液)的增溶作用,考察了不同浓度CC溶液的流变性能,选择CC质量分数为7%的溶液经过滤、脱泡后,以7%的稀硫酸为凝固浴进行溶液纺丝。结果表明:尿素增溶效果显著并提高了CC溶液的稳定性。经尿素增溶的CC溶液属于典型的切力变稀型流体,CC溶液经纺丝可得到直径为13～16μm的长丝,其纤维干态拉伸强度可达325～640MPa,断裂伸长率为10%～18%。     

Modification of regenerated cellulose membrane by impregnation of silver nanocrystal clusters

Regenerated cellulose forms a very important class of basic material with diverse applications because of its hydrophilicity and insolubility in water. Thus, one of the applications of regenerated cellulose is used to fabricate membranes. However, short operational lifetime is one of the disadvantages of the regenerated cellulose. In this research, surface modification of the cellophane membrane was carried out by silver nanoclusters. Silver colloids were formed in situ by chemical and photochemical reduction, and then, silver particles were deposited uniformly onto the surface of the cellophane membrane. The maximum amount of silver deposition was found to be 2.55% by weight in this modification. The modified and unmodified membranes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis to indicate silver nanocrystalline cluster particles on the modified membrane. SEM images indicate well-dispersed silver particles with an average size of 0.65 μm on the membrane. XRD patterns showed that the size of the silver crystals was 3.9 nm. The surface properties of modified and unmodified membranes were studied by the contact angle. Water absorption, oxidative resistance, salt permeability, and thermal stability were investigated. This study revealed that the modified membrane is more resistant against the oxidative cleavage than the unmodified one moreover, the salt permeability increased after the treatment. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48292.     

高吸水醋酸纤维素胶囊膜的制备

把醋酸纤维素制成胶囊膜，并将高吸水树脂封入胶囊中，制成高吸水醋酸纤维素胶囊膜，此膜可以用来浓缩水中的脲酶或悬浮微粒。     

Preparation and characterization of acrylic acid‐treated bacterial cellulose cation‐exchange membrane

The feasibility of using bacterial cellulose as a source for environmentally compatible ion‐exchange membranes (IEM) was studied. Bacterial cellulose was modified with cation‐exchangeable acrylic acid (AAc) by UV‐graft polymerization to prepare membranes having ion‐exchange capacity (IEC) and greater structural density. Fourier transform infrared (FTIR) spectra showed that acrylic acids were successfully bound to bacterial cellulose. Morphological changes of acrylic acid‐treated bacterial cellulose were examined through scanning electron microscopy. A dense structure of the membrane increased with increasing UV‐irradiation time. Acrylic‐modified bacterial cellulose membrane showed reasonable mechanical properties, such as tensile strength of 12 MPa and elongation of 6.0%. Also the prepared membranes were comparable to the commercial membrane CMX in terms of the electrochemical properties, ie IEC of 2.5 meq g^?1‐dry mem, membrane electric resistance of 3 ohm cm², and transport number of 0.89. Copyright © 2003 Society of Chemical Industry     

纤维素氨基甲酸酯的合成研究进展

纤维素氨基甲酸酯(CC)是一种再生纤维素产品,被视为黏胶工艺中纤维素磺酸酯最有潜力的替代产品。对CC的发展过程、研究现状、合成方法和应用性能进行介绍,对酯化反应中所使用的纤维素溶剂进行分类和总结,并详细介绍离子液体作为无副产物纤维素溶剂的研究进展。     

纤维素直接溶解成膜及其分离特性研究进展

借鉴纺织行业Lyocell纤维制备过程中采用的溶解方法,以N-甲基吗啉-N-氧化物（NMMO）为溶剂物理溶解纤维素,制备出了新型纤维素膜,并对其性能进行了测试.结果表明通过溶剂法制备的新型纤维素膜,应用潜力主要表现在3个方面：在湿态条件下对酸性气体具有较好的渗透性能;经过改性加入亚砜基团的纤维素膜对SO₂表现出较高且稳定的渗透性;因为纤维素的强亲水性,该膜应用于油水分离,其耐污染能力较强.     

纤维素/NMMO溶液及其薄膜的制备与性能研究

以水质量分数为13.3%的N-甲基吗啉-N-氧化物(NMMO)为溶剂溶解棉浆粕,制备质量分数为5%～11%的纤维素/NMMO溶液。将所得溶液制备纤维素薄膜,考察了纤维素/NMMO溶液的稳定性,研究了凝固浴温度和组成对纤维素薄膜的成膜性、断面形态及力学性能的影响。结果表明:纤维素/NMMO溶液随着浓度增大,其粘度先增大后减小,再急剧上升;纤维素/NMMO溶液在玻璃介质中稳定性较好,微量Cu~(2+),Fe~(3+)等杂质存在时,其稳定性显著下降;纤维素薄膜随凝固浴温度升高,其透明性、拉伸强度和断裂伸长率均下降;相对于水,含有乙醇和NMMO的凝固浴能减缓双扩散的速度,使纤维素薄膜的拉伸强度略有提高,断裂伸长率出现不同程度下降。     

Regenerated cellulose membrane prepared with ionic liquid 1‐butyl‐3‐methylimidazolium chloride as solvent using wheat straw

BACKGROUND: Currently, cellulose membranes are prepared by cellulose acetate hydrolysis or chemical derivatization dissolution and regeneration using cotton pulp or wood pulp. In this study, the concept ‘lignocelluloses biorefinery’ was used, and good quality long fiber was fractionated from wheat straw using clean technologies. The objective of this study is to develop wheat straw cellulose to prepare regenerated cellulose membrane with ionic liquid 1‐butyl‐3‐methylimidazolium chloride ([BMIM]Cl) as solvent. RESULTS: Wheat straw cellulose (WSC) fractionated from wheat straw contained 93.6% α‐cellulose and the degree of polymerization (DP) was 580. WSC was dissolved directly without derivatization in [BMIM]Cl. With increase in dissolving temperature, the DP of the regenerated cellulose dropped, which resulted in a decrease in the intensity of regenerated cellulose membrane. After regeneration in [BMIM]Cl, the WSC transformed from cellulose I to cellulose II, and the crystallinity of the regenerated cellulose was lower than the original cellulose. The regenerated WSC membrane had good mechanical performance and permeability, the tensile strength and breaking elongation were 170 MPa and 6.4%, respectively, the pure water flux was 238.9 L m^?2 h^?1 at 0.3 MPa pressure, and the rejection of BSA was stabilized at about 97%. CONCLUSION: Wheat straw cellulose fractionated from wheat straw satisfied the requirement to prepare regenerated cellulose membrane using ionic liquid [BMIM]Cl as solvent. Copyright © 2012 Society of Chemical Industry     

离子液体法制备再生细菌纤维素纤维

以离子液体(氯化1-甲基-3-正丁基咪唑)溶解高聚合度细菌纤维素(BC),采用湿法纺丝制备再生细菌纤维素(RBC)初生纤维;通过红外光谱分析(FTIR)、广角X射线衍射(WAXD)分析、热失重(TG)分析、扫描电镜( SEM)、单丝强度拉伸等表征了RBC初生纤维的结构和性能.结果表明:该溶剂体系通过10 h的快速搅拌溶...     

Properties of cellulose/PAN blend membrane

The water flux of a cellulose/PAN blend membrane increased with the PAN content, while retention to glucosan T40 decreased. The water flux decreased and the retention increased with the whole solid content. The membrane obtained had a high ability to remove creatinine and urea. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3105–3111, 2002; DOI 10.1002/app.10021     

纤维素/海藻酸钠共混膜的制备及力学性能

将纤维素和海藻酸钠分别溶于氢氧化钠/尿素/硫脲体系,制得纤维素膜和纤维素/海藻酸钠共混膜,通过正交实验和单因素实验法分析,确定制备纤维素膜的最佳工艺条件,在此基础上研究了纤维素/海藻酸钠共混膜的制备工艺。结果表明:质量分数为4.5%的纤维素溶液所制得的膜在25℃的5%的硫酸溶液中凝固15 min,20%的甘油溶液中塑化30 min,其膜的拉伸强度较佳为5.2 MPa;纤维素/海藻酸钠共混膜的较佳工艺:质量分数分别为4.5%的纤维素溶液和3%的海藻酸钠溶液按质量比100/5共混后先浸入5%硫酸溶液中反应15 min,再放入10%氯化钙溶液中凝固10 min,用15%甘油溶液塑化15 min后,共混膜的拉伸强度达到3.50 MPa。     

Palmitoylated cellulose nanocrystal/polycarbonate composite with high mechanical performance and good transparency

To fabricate polycarbonate (PC) composites with high mechanical and optical properties, PC composite films reinforced by cellulose nanocrystals esterified using palmitoyl chloride (palmitoylated cellulose nanocrystal [PAL-CNCs]) were fabricated by casting-evaporation and characterized by several techniques. It was shown that the PAL-CNCs with a substitution degree of 0.43 and the crystalline index of 53.3% were better dispersed in chloroform and tetrahydrofuran, and achieved a water contact angle of 81.0°. The crystallite size and crystalline index of the PC in the composite film significantly increased to more than 5.2 nm and 51.5%, respectively, after the incorporation of the PAL-CNCs. The PC composite film had an increase of 91.4% in tensile strength, 84.1% in Young's modulus, and a decrease of 5% in impact strength. Meanwhile, its UV–Vis-light transmittance was above 90%. Therefore, the palmitoylated -CNCs were a better candidate for engineering PC composites with high mechanical performance and transparency.     

过氧化氢氧化再生纤维素及其阻燃、吸附性能

以过氧化氢氧化再生纤维素(GC)制备羧基再生纤维素(OGC),表征OGC结构变化及其对阻燃和吸附性能影响机理。通过碱泡预处理能有效提高GC比表面积,增加反应效率,获得羧基含量达15.6%的OGC。FT-IR和¹³C NMR表征结果说明OGC葡萄糖基环上的C₆位伯羟基能被选择性氧化成羧基。随着羧基含量的提高,OGC无定形部分溶解而提高其结晶度,晶型则无显著变化,OGC的热分解温度下降,但是成炭率显著提高。当添加6.25%OGC为成炭剂用于环氧树脂膨胀型阻燃时,氧指数达到27.2,阻燃等级为V0。以火焰原子吸收分光光度法测定结果表明,当羧基含量为15.6%,OGC对铅和铜离子吸附量分别提高14倍和3.5倍,其原因在于氧化改性能显著提高OGC的比表面积和容积率,增加吸附容量。研究结果说明以过氧化氢氧化制备的OGC在阻燃成炭剂以及金属离子吸附领域中具有良好的应用前景。     

细菌纤维素膜的合成及表征

以海南椰子水为主要培养体系,实验室自行筛选的木醋杆菌(Acetobacter xylinum)为菌种,采用静态培养方法制备了细菌纤维素（BC）。对该BC和商业BC的结构和性能进行了测试对比,观察BC的微结构特点。结果表明: 制备的BC和商业BC在结构和一些性能方面是相似的,都是无色透明膜,呈三维网状结构和孔洞结构,具有良好的纳米纤维网络特征, 具有良好的吸湿性和极佳的持水能力,本实验制备的BC生产成本低,可根据需要大量制备,在生物医学领域具有良好的、广泛的应用前景。