Manufacture and properties of chitosan/N,O‐carboxymethylated chitosan/viscose rayon antibacterial fibers

Chitosan/N,O‐carboxymethylated chitosan/viscose rayon antibacterial fibers (CNVFs) were prepared by blending chitosan emulsion, N,O‐carboxymethylated chitosan (N,O‐CMC), and viscose rayon together for spinning. The fibers were characterized by transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). TEM micrographs showed that chitosan microparticles dispersed uniformly along the oriented direction with the mean size ranging from 0.1 to 0.5 μm. DSC spectra of these fibers showed that no significant change in thermal property was caused by adding chitosan and N,O‐CMC into the viscose rayon. TGA spectra showed that the good moisture retentivity was not affected by the addition of chitosan and N,O‐CMC. Both DSC and TGA suggested that the decomposing tendency of the viscose rayon above 250°C seemed to be weakened by the chitosan. The fibers' mechanical properties and antibacterial activities against Escherchia coli, Staphylococcus aureus, and Candida albicans were measured. Although the addition of chitosan slightly reduced the mechanical properties, the antibacterial fibers' properties were obtained and were found to meet commercial requirements. CNVF exhibited excellent antibacterial activity against E. coli, S. aureus, and C. albicans. The antibacterial activity increased along with the chitosan concentration and was not greatly affected by 15 washings in water. Scanning electron microscopy (SEM) was used to observe the morphology of bacteria cells incubated together with the antibacterial or reference fibers. SEM micrographs demonstrated that greater amounts of bacteria could be adsorbed by the antibacterial fiber than by the reference fiber; these bacteria were overwhelmingly destroyed and killed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2049–2059, 2002; DOI 10.1002/app.10501     

Microcrystalline chitosan. I. Preparation and properties of microcrystalline chitosan

A new type of microcrystalline polymer prepared by aggregation has been discussed. The effect of the parameters of the preparation process on the properties of microcrystalline chitosan in hydrogel and solid forms has been studied using also microscopy and spectroscopy. The product obtained according to the method discussed shows the average molecular weight within a range 2.2–5.0 X 10⁵, WRV_s ≈ 260–520%, WRV_g ≈ 700–1000%, and CrI up to 95%.     

Evaluation of microcrystalline cellulose prepared from kenaf fibers

A series of microcrystalline cellulose (MCC) were prepared from bleached kraft pulp of kenaf bast and core and compared with that from wood pulp. Hydrolysis of three kinds of pulp was carried out using hydrochloric acid. The properties of the produced MCC such as degree of polymerization (DP), crystallinity index (CrI), morphological features, bulk and tapping density, particle size and particle size distribution were examined, respectively. Highly native crystalline cellulose I form was characterized from all MCC samples. CrI values indicated that MCC from kenaf core (MCC-C) was more amorphous than both MCC from kenaf bast (MCC-B) and MCC from wood pulp (MCC-W). SEM micrographs showed that MCC-B and MCC-W displayed a rod-shaped morphology in their aggregates; MCC-C appeared to be a form of clusters. MCC-B had higher bulk and tapping density followed by MCC-W and MCC-C. The particle size distribution patterns indicated that all kinds of MCC samples fitted log-normal distribution and particle size mostly located in the range of 2–500 μm.     

Manufacture and performance of ethylamine hydroxyethyl chitosan/cellulose fiber in N-methylmorpholine-N-oxide system

Ethylamine hydroxyethyl chitosan (EHC), a novel chitosan derivative which is soluble in aqueous N-methylmorpholine-N-oxide (NMMO) and antibacterial to Escherichia coli (E. coli) was synthesized. The structure, solubility and antibacterial capability of EHC were investigated. Results demonstrated the potential application for EHC in manufacture of antibacterial EHC/cellulose Lyocell fiber. Through environment-friendly Lyocell process in aqueous NMMO, the EHC/cellulose fiber was successfully fabricated and the various properties of EHC/cellulose fiber were studied. Results showed the EHC/cellulose fiber exhibited favorable consistency, antibacterial activity, mechanical properties and water retention compared with the fiber without EHC.     

Surface modification of cellulose fibers. I. Spectroscopic characterization of surface-modified cellulose fibers and their copolymerization with styrene

Two coupling agents based on trichloro-s-triazine with different terminal unsaturated groups were synthesized in order to improve the bonding between cellulose fibers and an unsaturated polyester matrix. The products of the reactions between hydroxyl groups of cellulose and reactive species of coupling agents were analysed by Fourier-transform infrared spectroscopy (FTIR) and by elemental microanalyses. ESCA was used for surface characterization of treated fibers. The coupling agents were found to be concentrated on the fiber surface. Polymerization of styrene was carried out in the presence of treated fibers. That the unsaturated groups of the treated fibers were able to copolymrize with styrene was shown by FTIR. Further evidence of the presence of grafted polystyrene on the surfaces of the cellulose fibers was provided by ESCA measurements.     

Functional cellulose fibers via polycarboxylic acid/carbon nanotube composite coating

In this study, carbon nanotubes (CNTs) were stabilized on a cotton surface using 1,2,3,4-butanetetracarboxylic acid (BTCA) as a crosslinking agent and sodium hypophosphite as a catalyst. The influence of CNTs on the performance of the cellulose fiber was investigated using a Raman spectrophotometer, thermogravimetric analyzer, a scanning electron microscope, electrical contacting equipment, and an electromagnetic field detector. The possible interactions between CNTs, a crosslinking agent, and cellulose functional groups at the surface were elucidated by Raman spectroscopy. The results indicate that the stabilized CNTs modify the surface of the fibers and increase the functionality and thermal stability of the substrate. SEM showed a uniform coating of CNTs on the fiber surface.     

Evaluation of microcrystalline cellulose. I. Changes in ultrastructural characteristics during preliminary acid hydrolysis

Several microcrystalline celluloses prepared from viscose staple, bagasse, ramie, and cotton were evaluated by viscosimetry, X-ray diffraction and scanning and transmission electron microscopies. The changes in crystallinity, size of crystallites, grain-size distribution, morphological features, and degree of polymerization were found to be dependent on and greatly limited by the polymorphic conformations of cellulose. These changes were more conspicuous in cellulose II than in cellulose I. The coexistence of a two-phase system still remains in all the specimens of microcrystalline cellulose powders. Combining the findings with respect to the extent of the changes in the size of crystallites, it appears inevitable that recrystallization in some of the defective crystallites and degradation in the disordered areas of cellulose occurs simultaneously in the preliminary hydrolysis process during the production of microcrystalline cellulose. © 1996 John Wiley & Sons, Inc.     

Synthesis and characterization of polyurethane/microcrystalline cellulose bionanocomposites

In this study, novel polyurethane/cellulose hybrid bionanocomposite films have successfully been prepared by dispersing microcrystalline cellulose in a polyurethane matrix. Incorporation of microcrystalline cellulose in a polyurethane matrix improved the mechanical properties significantly. The polyurethane/cellulose bionanocomposites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction and transmission electron microscopy (TEM). The TEM results confirm that the nanoparticles were dispersed uniformly in polymer matrix. Additionally, thermogravimetric analysis data showed an improvement of thermal stability of novel nanocomposite films as compared to the neat polymer.     

微晶纤维素的研究进展

微晶纤维素具有独特的尺寸结构,其基质纤维素丰富价廉、可再生降解并具有良好的生物相容性,是天然高分子材料的重要分支.微晶纤维素的制备方法主要有酸水解法和酶解法;微晶纤维素除在传统行业有广泛应用外,还在增强复合、生物医学和光电科学等新兴领域有重要应用.最后对微晶纤维素的未来发展进行了展望和期待.     

Fabrication and characterization of zein/viscose textibe fibers

Azlons are increasingly concerned for their excellent performance properties and biodegradation. A kind of novel azlon, zein/viscose textibe fibers, were fabricated by wet‐spinning of zein and cellulose sulfonate blended solution. Some parameters that determine the fabrication process were optimized. The structure and properties of zein/viscose fibers were characterized, and compared with those of common viscose fibers. Dry breaking tenacity of zein/viscose fibers was 2.02 CN/dtex, whereas dry breaking elongation was 16.6%. Mechanical properties of zein/viscose fibers were a little better than common viscose fibers. The moisture regain rate of zein/viscose fibers was 14.1%, similar to that of viscose fibers. From the microstructure of zein/viscose fiber, viscose acted as framework and zein was accreted to viscose. The content of protein was 14.48% in zein/viscose fibers. The basic chains of zein and viscose were not changed by blended spinning, so the fibers had advantages of both zein and viscose. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Polymer-grafted cellulose fibers. I. Enhanced water absorbency and tensile strength

To enhance the water absorbency of wood fibers, various acrylic monomers were grafted to these fibers using cerium IV initiation followed by base hydrolysis. The absorbent capacity of hydrolyzed methyl acrylate- or acrylonitrile-grafted wood pulp fibers was an order of magnitude greater than ungrafted pulp fibers. A portion of this enhanced absorbency could be attributed to graft-induced osmotic forces. Enhanced absorbency was relatively independent of wood fiber type. Paper handsheets incorporating 20% grafted fibers had a fivefold increase in absorbent capacity, a twofold increase in dry tensile strength, a threefold or greater increase in wet tensile strength, and were more stretchable. In addition to enhanced absorbent capacity, the rate of absorbency was approximately 50% greater. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1463–1469, 1997     

微晶纤维素的羧甲基化反应

纤维素通过特殊的化学物理手段处理后，得到的微晶纤维素在有机溶剂中能很好地分散开，且所需要的有机溶剂的量较少。对其反应条件的探索表明，用微晶纤维素来进行羧甲基化反应，碱化和醚化时间较短，且一氯醋酸的利用率较高；用异丙醇作溶剂比乙醇作溶剂反应效果好。产物用1H－NMR研究表明，取代基在2位、3位和6位上的分布较均匀。     

Study of phase behavior on chitosan/viscose rayon blend film

A blend of chitosan and viscose rayon was investigated. A film was made from regenerating the blend of chitosan and viscose rayon. The film was characterized by various techniques, including Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray scattering (WAXS), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and transmission electron microscopy (TEM). The phase behavior of the blend is influenced by its composition with or without carboxymeth-ylated chitosan (CM-Cs). Characterization of the chitosan/viscose rayon (Cs/VR) blend by DSC and DMA suggests partial compatibility of chitosan with VR and lack of compatibility in the remaining cases. Results of the TEM show that the addition of CM-Cs into the blend can improve the compatibility of Cs with VR. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1965–1972, 1998     

Preparation and characterization of chitosan coatings onto regular cellulose fibers with ultrasound technique

Regenerated cellulose fibers—viscose fibers—were coated with chitosan using an ultrasound technique to improve their accessibility, reactivity and sorption properties. The main purpose of our research was to study the modification of viscose fibers and to determine the effect of the application of chitosan onto viscose fibers. Samples were obtained by treating the fibers with chitosan in a dilute acetic acid solution in an ultrasonic bath. The influences of the chitosan coating on the changes in morphology, supramolecular structure, sorption and tensile properties were studied. The spectra (FTIR analysis) of the treated viscose fibers showed changes and new absorption bands that revealed the existence of the chemical interactions with the chitosan. The scanning electron microscope images confirmed that the surface of the fibers was covered with the chitosan. A decrease in the water retention value and increase in the absorption and moisture content with an increasing concentration of chitosan was noted. Furthermore, the differences in tensile behavior were analyzed using an Instron tensile testing machine. The chitosan coating had no effect on the tensile strength of the viscose fibers, but influenced the tensile strain. Some changes, though not significant, were noted in the structure (crystallinity, orientation) of the treated viscose fibers.     

Properties of viscose prepared from modified cellulose

Conclusions Some basic characteristics of viscose prepared from radiation-modified cellulose as compared with standard viscose have been determined.It has been shown that viscose from RMC has an increased coagulation resistance and increased physicochemical uniformity as compared with standard viscose of analogous composition.Translated from Khimicheskie Volokna, No. 2, pp. 32–34, March–April, 1990.     

非晶态催化剂NiWB/CNTs催化微晶纤维素加氢反应

采用超声辅助浸渍化学还原法制备了一系列Ni WB-M/CNTs-A催化剂,并用于微晶纤维素加氢转化。用NH3-TPD和BET对催化剂进行了表征,考察了催化剂中不同的Ni/W比和催化活性组分负载量对催化剂性能的影响,同时还研究了催化反应条件对纤维素催化加氢性能的影响。TEM结果表明,催化剂为纳米颗粒且均匀地分散在载体上;SAED结果表明,催化剂具有非晶态结构;BET结果表明,催化剂孔径的大小是影响催化剂活性的主要原因之一;NH3-TPD结果表明,催化剂的强酸中心对纤维素转化起至关重要的作用。适宜的反应条件为:反应温度250℃、反应时间2.0 h、氢气压力6.0 MPa,在该条件下,纤维素的转化率为100%,乙二醇的产率为57.66%,六元醇的产率为10%。     

微晶纤维素的微细结构研究

研究了各种纤维素材料及不同酸浓度水解制成的微晶纤维素的聚合度，并用X-射线衍射法研究结晶度、结晶形态、晶粒尺寸和颗粒大小；用透射电镜（TEM）观察颗粒形状和大小，发现不同纤维素材料达到平衡聚合度（LODP）的盐酸浓度略有不同；在酸水解过程中纤维素的结晶形态、晶粒尺寸和颗粒大小基本不变，而且用X-射线衍射及TEM测出的颗粒不是纤维素晶粒，而是微原纤。     

Biocompatible regenerated cellulose/halloysite nanocomposite fibers

Regenerated cellulose (RC) bio-nanocomposite fibers reinforced with halloysite nanotubes (HNT) were fabricated through wet spinning technique via ionic liquid as a green solvent. Mechanical properties, water uptake, thermal stability, and cytocompatibility of the obtained fibers were examined. FTIR spectra indicated the uniform dispersion of HNT in the cellulose network. XRD analysis, together with FE-SEM images indicated that HNT was dispersed homogenously in the polymer. Moreover, mechanical and thermal stabilities of the nanocomposite fibers were notably increased through the addition of HNT. Eventually, human skin fibroblasts proliferation on nanocomposite fibers demonstrated good cyto-compatibility. These findings highlight the potential of HNT nanocomposite fibers for biological and biomedical applications.     

微晶纤维素增粘剂的研制

以棉浆为原料，废盐酸为水解催化剂，所得合成革用微晶纤锥素增粘剂的质量指标达到了德国和日本同类产品的标准。     

The effect of chemical composition of interphase on dispersion of cellulose fibers in polymers. I. PVC-coated cellulose in polystyrene

Cellulose fibers surface-coated with butyl benzyl phthalate (BBP)-plasticized PVC were evaluated as a reinforcement in thermoplastic matrices. Coated fibers were agglomerated during compounding with polypropylene (PP) and polyethylene (PE). However, an excellent dispersion and improved processability were achieved in polystyrene (PS). Melt rheology was also seen to be affected by fiber coating, and viscosity was lower for coated fibers. Fiber coatings seem to lubricate the blending process as well as to protect fiber from damage during processing. Fiber length was unaffected during treatment when coated fibers were used, as shown by microscopic investigation of extracted fibers, whereas the length of untreated fibers was reduced during processing. Introducing surface-coated fibers into PS resulted in an increased elongation at break and improved impact strength of composites. The pullout of the fibers is suggested to be responsible for both improvements. The interphase achieved in PS with PVC/BBP-coated fibers was simulated with PS/PVC/BBP blends. From DSC and DMTA, it was shown that BBP is a cosolvent for PS and PVC and that a single-phase material was achieved at the relevant concentrations, which also was confirmed by optical clarity. © 1993 John Wiley & Sons, Inc.