戊二醛交联改性再生纤维素纤维的研究

以氯化1-丁基-3-甲基咪唑离子液体为溶剂对木质纤维素进行溶解并纺丝,得到再生纤维素纤维,再使用戊二醛对再生纤维素纤维进行交联改性,研究其交联改性条件对再生纤维素纤维力学性能的影响。结果表明:经戊二醛交联后,再生纤维素纤维的断裂强度有明显的提高;在戊二醛质量分数为4%,反应温度为50℃,反应时间为30 min的交联条件下,所得再生纤维素纤维的断裂强度为3.2 cN/dtex。     

Comparison of cellulose and chitin nanocrystals for reinforcing regenerated cellulose fibers

In this study, regenerated cellulose fibers reinforced by cellulose nanocrystals (CENC) and chitin nanocrystals (CHNC) were prepared by blending the nanocrystals suspensions with the cellulose solution in NaOH/urea/water solvent at room temperature. The effect of nanocrystals' addition on the properties of spinning dopes and regenerated fibers were investigated and compared. Results showed that the obtained CENC and CHNC had different dimensions, and both of them increased the viscosity and decreased the transparency of the spinning dopes. However, the dissolution state of cellulose was not changed. CHNC had a greater influence on the properties of spinning dopes, while CENC had more obvious effect on the performance of regenerated fibers. The CENC reinforced fibers showed a higher crystallinity index as compared to the CHNC reinforced fibers. The tensile strength of the regenerated fibers was evidently improved when 3 wt % CENC or 2 wt % CHNC were added, while the elongation at break of the fibers was slightly decreased with the increase of nanocrystals content. The morphology and thermal stability of the regenerated fibers was not affected by the addition of nanocrystals. This study suggested that the dimension, group and content of nanocrystals were important factors for the reinforcement of regenerated cellulose fibers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44880.     

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...     

Preparation and characterization of cellulose carbamate membrane with high strength and transparency

In this study, cellulose carbamate was synthesized from alkali cellulose and urea by a low-cost solid–liquid phase method. Cellulose carbamate was dissolved in cuprammonium solution to form a regenerated cellulose membrane with high strength and high transparency. The mass fraction of cellulose dissolved was greatly increased (up to 17%), and the thermal stability of cellulose was retained. The surface of the membrane is compact and there are regular microchannels in it. The factors influencing the transparency and mechanical properties of regenerated cellulose membrane were discussed by the range analysis of orthogonal experiment. The light transmittance is 95.50%, the breaking strength is 98.35 MPa, the elongation at break is 21.74%. The ability of heat preservation and moisture preservation of regenerated cellulose membrane was tested, and the effect was close to that of conventional polyethylene membrane. The membrane material has broad application prospects in packaging, food preservation, agriculture, and other fields.     

Morphological investigation of cellulose acetate/cellulose nanocrystal composites obtained by melt extrusion

Composites were prepared from cellulose acetate (CA) and cellulose nanocrystals (CNC) by melt extrusion using two methods for the introduction of CNC: direct mixing and predispersion in CA solution. CNC were isolated using hydrochloric acid to increase thermal stability allowing the composites to be processed above 150 °C. The effect of CNC dispersion on the composites morphology, thermal, and mechanical properties was investigated. Field emission scanning electron microscopy and transmission electron microscopy results indicated that the predispersion method allows better CNC dispersion and distribution when compared to the direct mixture method. In addition, predispersion promotes preferential CNC orientation in relation to the injection flow. The predispersion method also showed a 14% Young's modulus increase in composites containing 15 wt % CNC while no significant change was observed when using the direct mixing. The results obtained in this work show that, to achieve the percolation threshold, nanoparticle distribution is as important as their content. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44201.     

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。     

功能性再生纤维素复合膜的制备及性能研究进展

纤维素是自然界中储量最大的天然高分子化合物,被认为是未来能源和化工的主要原料。然而,天然纤维素聚合度高、结晶度高的特性,使其难以溶于常规溶剂,极大限制了纤维素的应用。近年来,人们发现了多种新型纤维素溶剂体系,本文简要介绍了基于新型纤维素溶剂体系制备而来的再生纤维素膜以及一系列功能性再生纤维素基有机/无机复合膜材料。通过新型纤维素溶剂体系溶解再生得到的再生纤维素基复合膜在多孔性、热稳定性、强度等性能方面得到一定程度的改善,有望应用于包装、污水处理、传感器、生物医学等领域。本文基于再生纤维素膜及其复合膜材料的最新研究进展,对今后发展的热点方向进行了展望,旨在为纤维素溶解和功能性再生纤维素新材料的开发提供参考。     

再生木浆纤维素的制备及其稳定辛酸/癸酸甘油三酯乳液的性能研究

以高纯木浆板为原料制得再生木浆纤维素(W-RC),并用TEM、FT-IR和XRD对其进行表征,说明W-RC属于典型的纳米基纤维素Ⅱ型颗粒。以辛酸/癸酸甘油三酯(GTCC)为油相,W-RC为乳化剂,制得O/W型Pickering乳液,并通过光学显微镜、荧光显微镜、FE-SEM及流变仪对乳液进行表征。荧光显微镜与FE-SEM的结果显示W-RC吸附在油/水界面并在微球表面及微球间形成三维网状结构。流变学表明W-RC及由其稳定的乳液具有典型的剪切变稀特性。W-RC具有优良的乳化性能,在W-RC质量分数为0.6%、分散相体积分数高达60%时,也能得到稳定的乳液。     

Structure and properties of novel regenerated cellulose films prepared from cornhusk cellulose in room temperature ionic liquids

Cornhusk cellulose was regenerated using the ionic liquids viz., 1‐allyl‐3‐methylimidazolium chloride (AmimCl) and 1‐ethyl‐3‐methylimidazolium acetate (EmimAc). The cast cellulose films were characterized by FTIR, WAXD and SEM techniques. Their mechanical properties were also studied. These studies indicated that AmimCl and EmimAc are good solvents for the regeneration of cornhusk cellulose. The regenerated cornhusk cellulose (RCC) was found to be cellulose (II) with dense structure. The films cast from AmimCl exhibited good mechanical properties; the tensile modulus and strength were as high as 6 GPa and 120 MPa respectively, whereas these values for those films cast using EmimAc were found to be 4.1 GPa and 47 MPa respectively. Further, it was observed that after regeneration, the solvents could be effectively recycled. Thus a novel nonpolluting process of forming RCC films from agricultural waste was developed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Robust hydrogel of regenerated cellulose by chemical crosslinking coupled with polyacrylamide network

Regenerated cellulose/polyacrylamide (RC/PAAm) double network (DN) hydrogels are composed of cellulose crosslinked by epichlorohydrin (ECH) and chemical-crosslinked PAAm. The prepared RC/PAAm DN hydrogels present enhanced strength, good shape recovery property, excellent energy dissipation properties, decreased equilibrium water content, and low equilibrium swelling ratio (SR). The compressive strength and modulus of RC/PAAm hydrogel are about 4.3 and 11.5 times compared to that of RC hydrogel, respectively. Intriguingly, the chemical crosslinking between ECH and cellulose chains could increase the distance between cellulose chains. Consequently, the increasing molar ratio of ECH to glucose leads to larger SRs and decreased mechanical strength of the hydrogels. Additionally, higher PAAm contents lead to more densely crosslinked networks, and thus decreasing the SRs and improving the mechanical strength of the hydrogels. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47811.     

再生纤维素/壳聚糖/银纳米线抗菌复合膜制备及性能

以1-丁基-3甲基咪唑氯盐（[Bmim]Cl）为溶剂体系，通过微晶纤维素（MCC）溶解再生制备基膜，壳聚糖（CS）、银纳米线（AgNW）共混液包覆方法制备抗菌复合膜，通过FTIR、XRD、SEM和热重分析对复合膜的形貌和结构进行表征及对力学、光学、阻隔、抑菌等性能测试分析。结果表明，壳聚糖和银纳米线成功复合于纤维素基膜，与再生纤维素膜相比，当AgNW质量分数为0.5%时，复合膜的拉伸强度提升了12.2%，透光率保持在89.82%，氧气透过率下降了86.7%，且对大肠杆菌具有良好的抑制作用，制备出一种力学性能、光学性能、阻隔性能、抗菌性能优异的可降解纤维素/壳聚糖/银纳米线抗菌复合膜。     

Morphological and structural formation of the regenerated cellulose membranes recovered from its cuprammonium solution using aqueous sulfuric acid

Morphological and structural formation of the regenerated cellulose membranes from its cuprammonium hydroxide solution by acid coagulation was investigated. Scanning electron microscopic observation revealed that the morphology of the membranes changed drastically as functions of both the cellulose concentration in the original cellulose solution C_Cell and the concentration of sulfuric acid as a coagulant C_H2SO4. It was found that at a constant polymer concentration (8 wt %) the membrane prepared by using 5 wt % aqueous sulfuric acid exhibits higher water flux, far smaller swelling anisotropy parameter L_t, and larger porosity P_r with a thinner skin structure, and these parameters were proven to be associated with lower (11 0) crystal plane orientation coefficient f_{∥(11 0)} compared with those for the membranes obtained by aqueous sulfuric acid with more than 10 wt %. On the other hand, at constant coagulant concentration (10 wt %) the membrane prepared by using the polymer solution with 5 wt % shows far greater P_r with practically no distinct skin structure; hence, a higher flux. The drastic changes in the morphology and structural parameters as functions of C_Cell and C_H2SO4 were found to be well correlated with abrupt changes in material transportation (copper ion, ammonium ion, and water) from the polymer solution to aqueous coagulants as a function of C_Cell and C_H2SO4. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1669–1678, 1999     

新型溶剂法制备再生纤维素纤维研究进展

再生纤维素纤维以可再生、可生物降解的天然纤维素为原料,它的研究和开发对充分利用纤维素资源和促进纤维行业的可持续发展具有重要意义.离子液体和碱溶液溶剂体系对纤维素具有独特的溶解性能,为再生纤维素纤维的制备提供了新方法.这种新型的再生纤维素纤维具有制备过程简单、对环境无污染、纤维力学性能优异或生产成本低等优点,发展前景十分广阔.综述了离子液体法和碱溶液法再生纤维素纤维的最新研究进展,包括溶剂种类及其溶解能力、纤维素原料的性质与选择、纤维的制备方法和力学性能等,同时归纳和对比了各因素对新型再生纤维素纤维力学性能的影响.最后展望了两种新型再生纤维素纤维存在的挑战、未来发展趋势和工业化前景.     

单壁碳纳米管/再生纤维素复合纤维的制备及性能

将经过酸化处理和十二烷基苯磺酸钠处理后的单壁碳纳米管(SWNTs)与离子液体和再生纤维素共混制得纺丝溶液,通过干湿法纺丝制得SWNTs/再生纤维素复合纤维.考察了SWNTs处理前后的结构及在离子液体中的分散性;研究了复合纤维的力学性能和热性能.结果表明:经酸化和功能化处理后的SWNTs的直径有所减小,SWNTs在离子液...     

Feasibility of recycled newspaper as cellulose source for regenerated cellulose membrane fabrication

An environmental friendly regenerated cellulose membrane (RCM) was successfully prepared via NaOH/urea aqueous solution system by utilizing recycled newspaper (RNP) as the cellulose source. The morphological and chemical structure of resulting membrane were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD) spectroscopy, and thermogravimetric analysis (TGA). Results from FTIR and XRD verified that the transparent RCM possesses cellulose II structure. SEM observation revealed that the transparent RCM consist of homogeneous dense symmetric membrane structure and composed of a skin layer with mean roughness parameter R_a, obtained from AFM analysis of 29.53 nm. Pure water flux, water content, water contact angle, porosity, and pore size of the resulting membrane were also measured. This study promotes the potential of the cellulose‐based membrane obtained from low cost cellulose source for application in filtration and separation system. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42684.     

Reactivity of glycidyl methacrylate grafted cellulose film prepared by grafting under ultrasonic irradiation

Ultrasonic irradiation largely accelerated ceric salt initiated grafting of glycidyl methacrylate (GMA) on regenerated cellulose film (cellophane thickness = 20 μm) at 60°C in air. The grafting under ultrasonic irradiation was characterized by a higher percent of grafting and graft efficiency and a lower density of GMA‐grafted chains in the surface layer of the grafted films compared to the unirradiated system, which was obtained by attenuated total reflectance IR measurements. The grafted films were subjected to amination with ethylenediamine (En) at 70°C for 3 h in N,N‐dimethylformamide. The amount of epoxy groups in the grafted films, which participated in the reaction with En, reached about 50–60 mol % and was slightly lower for the grafted film prepared in the irradiated system than that prepared in the unirradiated one. Adsorption of cupric ions with the aminated samples was performed at pH 5.0 using Clark–Lubs buffer solution and cupric chloride. The adsorption was extremely retarded for the aminated sample prepared using the unirradiated sample compared to that prepared using the irradiated one. The retarded adsorption phenomenon is discussed in terms of a larger formation of crosslinked structures on the surface layer of the former sample during the amination. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2462–2469, 1999     

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     

Surface‐initiated atom transfer radical polymerization of regenerated cellulose membranes with thermo‐responsive properties

Using atom transfer radical polymerization (ATRP), thermo‐responsive regenerated cellulose membranes were synthesized. Regenerated cellulose membranes were firstly modified by reacting the hydroxyl groups on the surface with 2‐bromoisobutyryl bromide, followed by grafting with poly(N‐isopropylacrylamide). The membranes had obvious thermally modulated permeability properties. Analysis was carried out by means of X‐ray photoelectron spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis. The results showed that N‐isopropylacrylamide had been grafted successfully on the surface of the regenerated cellulose membranes. The thermally modulated permeability properties of the grafted membranes were studied using water flux measurements. It was found that the thermally modulated permeability properties of a cellulose surface can be tailored by the use of the ATRP method. Copyright © 2010 Society of Chemical Industry