Composite Fibers Based on Chitin

Composite fibers containing chitin and cellulose ethers (methyl, hydroxyethyl, and hydroxypropyl cellulose) and also chitin and polyvinylpyrrolidone were prepared. The effect of the ratio of system components and also the molecular weight of polyvinylpyrrolidone on the deformation-strength characteristics of the composite fibers and their supramolecular organization was studied.     

Composite Fibers Based on Hydrated Cellulose and Poly-N-vinylpyrrolidone,Prepared from Cellulose Solutions in N-Methylmorpholine-N-Oxide

Russian Journal of Applied Chemistry - Hydrophilic composite fibers of various compositions were prepared from mixtures of solid solutions of cellulose in N-methylmorpholine-N-oxide or its...     

Chitin and Chitosan Fibers

Chitin and chitosan are natural polymers extracted from various plants and animals. In recent years, these two polymers have attracted much interest because of their biodegradability, biocompatibility, wound-healing acceleration and many other unique properties. As a natural renewable resource, they offer many potential applications in a number of diversified fields. Chitin and chitosan fibers have been found useful as a biomaterial for potential applications such as sutures and wound dressings. This article presents a brief introduction to the properties of chitin and chitosan, and reviews the various attempts for the production of fibers from the two polymers. © 1997 John Wiley & Sons, Ltd.     

Thermomechanical Analysis of Composite Films Based on Chitosan and Chitin Nanofibrils

Russian Journal of Applied Chemistry - Nanocomposite films based on chitosan and filler in the form of chitin nanofibrils were prepared. An analysis of the film morphology by scanning electron...     

离子液体中纤维素/纳米层状ZnO复合抗菌纤维的制备及性能

以表面活性剂十二烷基磺酸钠(SDS)为模板,Zn(NO_3)_2·6H_2O和NaOH为锌源和沉淀剂,通过改进的模板法在温和条件下制得纳米层状ZnO.以离子液体1-烯丙基-3-甲基咪唑氯盐([Amim]Cl)为溶剂,木浆纤维素和纳米层状ZnO为原料,采用溶液共混方法,通过干湿法纺丝制备了ZnO质量分数分别为3%,5%,7%及9%的纤维素/ZnO纳米复合纤维.采用X射线衍射(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)、场发射扫描电子显微镜(SEM)及热重分析(TG)等方法对纳米层状ZnO及纤维素/ZnO复合纤维进行了表征,并探讨了ZnO的加入对复合体系流变性的影响,同时对复合纤维进行了力学和抗菌性能测试.研究结果表明,所制备氧化锌纯度高,且呈现出重复周期为3.58 nm的层状结构,抗菌性能优异.纳米层状ZnO的加入提高了纤维素纤维的热稳定性和机械强度,同时赋予纤维对金黄色葡萄球菌和大肠杆菌的抑菌性.ZnO片层被纤维素链剥离,并均匀分散于纤维素/ZnO复合物中.ZnO的加入增大了纤维素溶液的黏度,当ZnO含量达到5%以上时,在整个频率范围内,弹性模量大于损耗模量,纳米粒子可稳定悬浮.     

Composite Films Based on Polyvinyl Alcohol and Na-Carboxymethyl Cellulose for Separation

Russian Journal of Applied Chemistry - The possibility of using composite films based on polyvinyl alcohol (PVA) and Na-carboxymethylcellulose (Na-CMC) as a separating material is considered for...     

Rheological,Thermal, and Morphological Characteristics of Plasticized Cellulose Acetate Composite with Natural Fibers

Plasticized cellulose acetates processed with biofibers like industrial hemp and henequen were investigated with respect to their thermal, morphological and rheological characteristics. Discernable fibril morphologies in the biocomposites were observed via a SEM investigation. Such morphological characteristics were further analyzed with the results of TGA and rheometry. Furthermore, the obtained rheological properties were also interpreted in conjunction with the formation and destruction of internal structure in biocomposites.     

Fabrication of Hollow Materials by Fast Pyrolysis of Cellulose Composite Fibers with Heterogeneous Structures

A facile method for the fabrication of inorganic hollow materials from cuprammonium cellulose composite filaments based on fast pyrolysis has been developed. Unlike Ostwald ripening, approaches based on the Kirkendall effect, and other template methods, this process yielded hollow materials within 100 s. The heterogeneous structure of the cellulose composite fibers and the gradient distribution of the metal oxides are the main reasons for the formation of the hollow structure. The diameter, wall thickness, and length of the hollow microfibers could be conveniently controlled. With their perfect morphology, these hollow structural materials have great potential for use in various fields.     

Direct Organocatalytic Polymerization from Cellulose Fibers

Summary: We have developed the first direct, organocatalytic, bulk ring‐opening polymerization (ROP) of ε‐caprolactone (ε‐CL) with solid cotton and paper cellulose as the initiators. The mild ROPs were performed without solvent, and are operationally simple, inexpensive and environmentally benign. Organic‐acid‐catalyzed heterogeneous derivatization of cellulose provides a novel route to valuable cellulose‐based biocompatible nanomaterials. The furnished polymerization products were characterized by FTIR, ¹H and ¹³C NMR spectroscopy, MALDI‐TOF mass spectrometry and electron microscopy.

Organic acid‐catalyzed ring‐opening polymerization from cellulose fiber.     

Synthesis of Carboxymethyl Cellulose Based on Short Fibers and Lignified Part of Flax Pedicels (Boon)

The conditions under which carboxymethyl ethers of cellulose with various degrees of substitution can be prepared from wastes formed in production of flax fibers were studied. The structure of the cellulose ethers synthesized was studied by IR Fourier spectroscopy and physicochemical methods.     

高力学强度细菌纤维素气凝胶纤维的连续化制备

气凝胶纤维因其高外表面积和高柔韧性在能量管理系统中具有潜在应用而引起了广泛关注.但是,目前制备的气凝胶纤维力学强度较低,限制了其实际应用.为提高气凝胶纤维力学性能,在始终保持细菌纤维素(BC)纳米纤维处于湿态下,利用NaOH/尿素/硫脲复合溶剂直接低温溶解原生BC,获得透明的BC纺丝原液;通过湿法纺丝制备了BC水凝胶纤维,经过水洗和冷冻干燥后处理,制得BC气凝胶纤维.采用偏光显微镜(POM)、13C核磁共振(13C-NMR)和高级旋转流变仪研究BC在复合溶剂中的溶解过程与状态;利用全反射傅里叶变换红外吸收光谱(ATR-FTIR)、X射线衍射(XRD)和热失重(TG)研究BC溶解前后结构与性能变化;利用场发射扫描电镜(FESEM)、全自动比表面积和孔径分布分析仪、单丝强力仪对获得的BC气凝胶纤维结构与性能进行表征.结果表明,复合溶剂在?15℃条件下可以直接溶解原生湿态BC,最高溶解浓度为3 wt%;采用湿法纺丝制得高度多孔的连续BC气凝胶纤维,比表面积高达192 m^2/g且具有优异的力学性能,断裂强度和杨氏模量高达(9.36±1.68)MPa和(176±17.55)MPa,如0.4 mg BC气凝胶纤维可以支撑高于其本身质量5×10^4倍的重物.     

Bioinspired Green Composite Lotus Fibers

Owing to the growing global environmental problems, demands for environmentally friendly, fully biodegradable sustainable composites have substantially increased across various industries. Inspired by the composite structure of cocoon silk, we fabricated a fully green composite fiber (GCF) that is based on the lotus fiber (LF) and a biodegradable polymer, namely poly(vinyl alcohol) (PVA). After the formation of cross‐linkages between the LF and PVA, the mechanical properties of this bioinspired GCF had substantially improved. In particular, the specific mechanical properties are superior to those of cocoon silk and other natural fibers. These findings suggest that LFs may be used as reinforcement materials for the fabrication of bulk green materials for various industries, such as the textile, medical, automobile, and aerospace industries.     

Extraction and Characterization of Natural Cellulose Fibers from Maize Tassel

This article reports on the extraction and characterization of novel natural cellulose fibers obtained from the maize (tassel) plant. Cellulose was extracted from the agricultural residue (waste biomaterial) of maize tassel. The maize tassel fibers were obtained after treatment with NaOH and were carefully characterized while the chemical composition was determined. The chemical composition of the maize tassel fibers showed that the cellulose content increased from 41% to 56%, following alkali treatment. FT-IR spectroscopic analysis of maize tassel fibers confirmed that this chemical treatment also shows the way to partial elimination of hemicelluloses and lignin from the structure of the maize tassel fibers. X-ray diffraction results indicated that this process resulted in enhanced crystallinity of the maize tassel fibers. The thermal properties of the maize tassel fibers were studied by the TGA technique and were found to have improved significantly. The degradation temperature of the alkali-treated maize tassel fiber is higher than that of the untreated maize tassel fibers. This value convincingly showed the potential of maize tassel fibers for use in reinforced biocomposites and waste water treatment.     

Novel Thermoplastic Composites from Commodity Polymers and Man-Made Cellulose Fibers

Summary: A new class of fibre reinforced commodity thermoplastics suited for injection moulding and direct processing applications has been developed using man-made cellulosic fibres (Rayon tire yarn, Tencel, Viscose, Carbacell) and thermoplastic commodity polymers, such as polypropylene (PP), polyethylene (PE), high impact polystyrene (HIPS), poly(lactic acid) (PLA), and a thermoplastic elastomer (TPE) as the matrix polymer. For compounding, a specially adapted double pultrusion technique has been employed which provides composites with homogeneously distributed fibres. Extensive investigations were performed with Rayon reinforced PP in view of applications in the automotive industry. The Rayon-PP composite is characterized by high strength and an excellent impact behaviour as compared with glass fibre reinforced PP, thus permitting applications in the field of engineering thermoplastics such as polycarbonate/acrylonitrile butadiene styrene blends (PC/ABS). With the PP based composites the influence of material parameters (e.g. fibre type and load, coupling agent) were studied and it has been demonstrated how to tailor the desired composite properties as modulus and heat distortion temperature (HDT) by varying the fibre type or adding inorganic fillers. Man-made cellulose fibers are also suitable for the reinforcement of further thermoplastic commodity polymers with appropriate processing temperatures. In case of PE modulus and strength are tripled compared to the neat resin while Charpy impact strength is increased five-fold. For HIPS mainly strength and stiffness are increased, while for TPE the property profile is changed completely. With Rayon reinforced PLA, a fully biogenic and biodegradable composite with excellent mechanical properties including highly improved impact strength is presented.     

新溶剂法纤维素纤维的技术进展

传统的粘胶纤维存在源头污染问题,有必要开发符合环保和资源可再生要求的新溶剂法纤维素纤维生产技术,以作为未来纤维材料的大宗品种.在已开发的众多纤维素溶剂体系中,NMMO(N-甲基吗啉-N-氧化物)溶剂体系已形成了规模化生产;纤维素氨基甲酸酯、氢氧化钠或氢氧化锂/硫脲或锌酸钠或(和)尿素水溶液、离子液体溶剂体系的开发也取得了较大进展.以NMMO为代表的有机溶剂法纤维素纤维产业化工程技术中,连续真空薄膜推进溶解技术具有对比优势;纺丝技术均为干喷湿纺;溶剂回收技术的发展方向是提浓过程的高效蒸发并结合其它节能技术;原纤化控制技术在规模化生产中采用干燥前在线交联.     

Modified Cellulose Fibers as Reinforcing Fillers for Macromolecular Matrices

Various cellulose substrates were submitted to different surface OH chemical modifications in non-swelling media and then fully characterised by FTIR, XPS, contact angle measurements and elemental analysis. The alternative procedures adopted were: (i) simple grafting with monomeric or oligomeric agents which bore one or several reactive functions, either as a single terminal moiety or as numerous moieties placed along the chain; (ii) grafting with polymerisable molecules, which involved the use of reagents of small molecular size, but bearing two functions, one able of reacting with the surface cellulose OH groups and the other used as a source of subsequent covalent linkage with the matrix; (iii) the use of planar stiff molecular configurations bearing two identical reactive functions, calling upon the working hypothesis that only one function will react with a cellulose OH group, whereas the other will be left to copolymerise with the matrix; (iv) coupling with siloxanes using the same strategy as in (ii), except for the fact that this specific approach involves molecules already commonly used in glass fibres treatment; (v) grafting with organometallics such as triethyl aluminium following the same working hypothesis as in (iii) but with a second reaction involving monomeric or polymeric alcohols or amines.     

Water-Resistant and Stretchable Conductive Ionic Hydrogel Fibers Reinforced by Carboxymethyl Cellulose

Conductive ionic hydrogels (CIH) have been widely studied for the development of stretchable electronic devices, such as sensors, electrodes, and actuators. Most of these CIH are made into 3D or 2D shape, while 1D CIH (hydrogel fibers) is often difficult to make because of the low mechanical robustness of common CIH. Herein, we use gel spinning method to prepare a robust CIH fiber with high strength, large stretchability, and good conductivity. The robust CIH fiber is drawn from the composite gel of sodium polyacrylate (PAAS) and sodium carboxymethyl cellulose (CMC). In the composite CIH fiber, the soft PAAS presents good conductivity and stretchability, while the rigid CMC significantly enhances the strength and toughness of the PAAS/CMC fiber. To protect the conductive PAAS/CMC fiber from damage by water, a thin layer of hydrophobic polymethyl acrylate (PMA) or polybutyl acrylate (PBA) is coated on the PAAS/CMC fiber as a water-resistant and insulating cover. The obtained PAAS/CMC-PMA and PAAS/CMC-PBA CIH fibers present high tensile strength (up to 28 MPa), high tensile toughness (up to 43 MJ/m³), and good electrical conductivity (up to 0.35 S/m), which are useful for textile-based stretchable electronic devices.