Modified Cellulose Fibers Research Articles

Effect of cationic polyelectrolytes in contact-active antibacterial layer-by-layer functionalization

Abstract Contact-active surfaces have been created by means of the layer-by-layer (LbL) modification technique, which is based on previous observations that cellulose fibers treated with polyelectrolyte multilayers with polyvinylamine (PVAm) are perfectly protected against bacteria. Several different cationic polyelectrolytes were applied, including PVAm, two different poly(diallyl dimethyl ammonium chloride) polymers and two different poly(allylamine hydrochloride) polymers. The polyelectrolytes were self-organized in one or three layers on cellulosic fibers in combination with polyacrylic acid by the LbL method, and their antibacterial activities were evaluated. The modified cellulose fibers showed remarkable bacterial removal activities and inhibited bacterial growth. It was shown that the interaction between bacteria and modified fibers is not merely a charge interaction because a certain degree of bacterial cell deformation was observed on the modified fiber surfaces. Charge properties of the modified fibers were determined based on polyelectrolyte titration and zeta potential measurements, and a correlation between high charge density and antibacterial efficiency was observed for the PVAm and PDADMAC samples. It was demonstrated that it is possible to achieve antibacterial effects by the surface modification of cellulosic fibers via the LbL technique with different cationic polyelectrolytes.

Advanced three-dimensional paper structures: Mechanical characterization and forming of sheets made from modified cellulose fibers

Cellulose partially converted to dialcohol cellulose has been identified as a potential breakthrough material for the production of bio-based, complex, double-curved surfaces due to its extensive strain-at-break characteristics (reaching as great as 80% in tensile loading). Tensile testing of handsheets made from modified cellulose fibers was conducted from 50 to 90% relative humidity (RH) and from 23 to 150 °C. Strain-at-break of the handsheets ranged from 35 to 80% over this humidity and temperature range, which is significantly greater than typical cellulose-based materials. The combined effect of moisture and temperature was further investigated by dynamic mechanical thermal analysis, which was utilized to determine the glass-transition temperature of the handsheets as a function of relative humidity. Based on the tensile test results and verified by the three-dimensional (3-D) forming and simulation, a forming limit diagram (strain-based failure surface which describes and illustrates the formability of the material) for the handsheets was generated. This forming limit illustrates significant extent to which this bio-based material can be 3-D formed into advanced structures. Furthermore, temperature was identified as the best, quickest, and most controllable method of improving extensibility of this material during 3-D forming.

Synthesis of silver nanoparticles in NMMO and their in situ doping into cellulose fibers

We present a method for synthesis of silver nanoparticles in N-methylmorpholine N-oxide (NMMO) and the associated mechanism, as well as their use for in situ volume modification of cellulose fibers. The synthesized particles had diameter of about 4 nm, and their colloid solution was stable for 1 year. The nanoparticles were stabilized using polyethylenimine, which apart from preventing nanoparticle agglomeration, also accelerated Ag+ ion reduction and prevented NMMO degradation. A mechanism for the nanoparticle synthesis is suggested based on the electrochemical potentials of all ions in solution, with perhydroxyl ions resulting from NMMO reducing the silver ions. We also created nanocomposites from fibers and silver nanoparticles, in which the latter showed very good dispersion in the fiber volume. Such spun fibers showed improved mechanical parameters in comparison with unmodified fibers.

Modified cellulose fibers as adsorbent for dye removal from aqueous environment

Modified cellulose fibers as adsorbent for dye removal from aqueous environment

Enhancement of Hydrophobic Properties of Cellulose Fibers via Grafting with Polymeric Epoxidized Soybean Oil

We report on an efficient method for the formation of modified cellulose-based materials with enhanced hydrophobic properties, formed by grafting with polymeric epoxidized soybean oil (ESO) as a renewable, environmentally friendly, and low cost raw material. The grafting process occurred via ring-opening polymerization, wherein the cellulose hydroxyl groups acted as initiators in the presence of a SnCl4 catalyst, linking the cellulose fibers and ESO via ether linkages, thereby forming a polymeric matrix. The surface polarity was therefore decreased by the substitution of cellulose hydroxyl groups for long-chain hydrophobic alkane moieties from ESO. The water contact angle of modified filter paper reached 145.1° with the surface free energy decreasing to 22.07 mJ m–2 and a hydration free energy of −13.09 mJ m–2. The presence of polymeric ESO nanoparticles on the modified cellulose fibers suggested that the hydrophobicity was not only dependent on the surface composition but was also closely related to the ...

Cellulose fiber-reinforced high-density polyethylene composites—Mechanical and thermal properties

In this investigation, the thermal and mechanical properties of cellulose fibers from sugarcane bagasse reinforced with high density polyethylene composites were evaluated. Cellulose fibers were modified with hydrous Zr oxide to clean the fiber surface and improve the fibers–matrix adhesion. Composites were manufactured using a thermokinetic mixer process and the fiber content was responsible for 5, 10, 20, 30, and 40wt% in the composition. The chemical modification of the cellulose fibers with zirconium oxide was verified by FTIR analysis and the fibers’ morphological aspects by SEM. After the chemical modification, the FTIR results showed reduction of OH bonds. SEM characterization showed that the modification changed the morphology of fibers. The results show that composites reinforced with modified cellulose fibers have an improvement in the thermal and mechanical properties, when compared to the non-cellulose fibers. In addition, an enhancement on the mechanical properties of composites was found, i.e. a gain of 122.4% compared to neat polymer at 40wt.% fiber loading in Young’s modulus. The thermal properties show a slight decrease with increase of modified cellulose.

Mercerization mediated modification of cellulosic fibers with NIPAAm and some compounds with antioxidant activity

A two step process was used for the modification of a cellulose/chitin mixed fibers: the first step was an alkali treatment with a NaOH solution (20 %), which was followed by the reaction with one of the reagents such as Nisopropylacrylamide, p-hydroxybenzoic acid, gallic acid, or eugenol. Both the samples activated with the alkali treatment and modified with chemicals were characterized by attenuated total reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and thermal analysis. Results revealed the morphological and structural changes of the fiber surface after the surface grafting, which significantly altered the cellulose/chitin mixed fiber properties. Thermal analysis results showed an increase in the thermal stability of the treated samples. Antioxidant activity of cellulose/chitin mixed fibers modified with phenolic compounds showed that the efficiency depends on the chemical nature of phenolic compound.

Biocomposites based on chemically modified cellulose fibers with renewable fatty‐acid‐based thermoplastic systems: Effect of different fiber treatments

ABSTRACTAdvanced biocomposites, based on binary and ternary systems, were developed with thermoplastic matrices such as thermoplastic polyurethane (TPU) and polyamide (DAPA) obtained from dimers of fatty acids, and cellulose fibers (CF). The CF were modified to display high interfacial adhesion and compatibility with the rather hydrophobic matrices. Different routes were considered such as grafting onto with prepolymers, or grafting from with aromatic isocyanate or fatty acid. An original approach of this work is to consider CF as a polyol with an equivalent hydroxyl index obtained by titration. In order to understand better the effect of each phase, the resulting modified CF were tested with neat TPU and DAPA matrices. The most promising fibers treatments were then tested with 80/20 and 50/50 wt %/wt % TPU/DAPA blends. Properties at the molecular and macromolecular scale were investigated. Improvement of the interfacial adhesion between the fibers and the polymers were observed. From the different grafting approaches tested, the best performing were the isocyanate‐terminated prepolymer and the silane‐terminated prepolymer modifications. In comparison with neat CF, modification with isocyanate‐terminated prepolymer improved threefold the storage and Young's modulus of TPU biocomposites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43878.

Hydrophobic modification of bagasse cellulose fibers with cationic latex: Adsorption kinetics and mechanism

The modification of the bagasse cellulose fiber by the adsorption of cationic poly latex with core–shell structure on fiber surfaces was conducted in attempt to enhance the interfacial compatibility between hydrophilic fibers and the hydrophobic substrates for various applications. A two-step semi-batch emulsion polymerization was employed for constructing core–shell latex. TEM and dynamic light scattering (DLS) analysis indicated that the core–shell latex possessed a broad particles size distribution, which led to the adsorption of the latex on fiber proceeding via two-stage equilibrium mainly due to the effect of latex particle size. The pseudo-first-order kinetic model was appropriate for the description of the kinetics of the first stage equilibrium at high latex concentration and the entire adsorption process at low concentration. In contrast, the pseudo-second-order kinetic model fitted the second equilibrium at high latex concentration well. The activation energy calculated suggested that the number of activated molecules was increased as the increase of adsorbent concentration, which might change the dominant adsorption mechanism. This also addressed the reasons for the abnormal adsorption behavior with the extra-added emulsifier. In addition, the surface property of the modified cellulose fibers was also investigated via contact angle measurements. The results proved that the cellulose fiber modified with the latex became hydrophobic, allowing the as-modified cellulose to be potential reinforcements for biocomposite. Finally, the adsorption mechanism was proposed according to the adsorption process mainly governed by electrostatic interactions, hydrogen bond, π–π stack and chain entanglement.

New cellulose based ionic compounds as low-cost sorbents for CO2 capture

Supporting ionic liquids in solid materials is a promising solution to address CO2 capture. Cellulose is a versatile and low-cost material. The support of different ionic liquids cations on cellulose extracted from rice husk is an excellent strategy for CO2 capture. This study reports chemical modification of cellulose fibers extracted from rice husk with different ionic liquids cations and its potential for CO2 capture. The obtained ionic compounds were characterized by FTIR, XRD, FESEM, TGA and BET. CO2 sorption capacity was gravimetrically assessed in a Magnetic Suspension Balance (MSB). In addition, ab Initio calculations were performed. First, the carboxylate groups are responsible for the CO2 capture process. Second, the cation maintains the CO2 binding sites of the anion partially or fully non-occupied, improving the CO2-ionic compound affinity. The best result for CO2 sorption was obtained for the ionic compound CL-TBA of 71mgCO2/g at 3MPa and 25°C. At lower pressures, this compound presents a high CO2 sorption value (44mgCO2/g at 0.1MPa). We conclude that these ionic compounds deserve further attention in the post-combustion process.

Transparent composite films prepared from chemically modified cellulose fibers

Mixtures of partially carboxymethylated softwood kraft pulp fibers (CMF) and carboxymethylcellulose (CMC) are made into CMF/CMC “composite” films without mechanical fibrillation or high temperature pressing. Drying conditions largely influence the physical appearance of the pulp fibers upon carboxymethylation, as an efficient and complete structural collapse of the swollen fibers is required to achieve transparency. Ethanol dried CMF/CMC mixtures produce white, fluffy fibers with increased water absorbency. Such improvement in water absorbency is most likely due to the presence of structurally deformed CMF which provide intrinsic water pockets along with the hydrophilic nature of CMC. On the other hand, thin films with different transparency can be prepared when CMF/CMC mixtures are dried at 50 °C from aqueous suspensions. Physical and optical properties of the CMF/CMC films are mainly dependent on the degree of substitution (DS), as well as pH. With an increase in the DS, tensile strength, Young’s modulus, density, transparency, water absorbency, and gas barrier property are all increased. Tensile strength and Young’s modulus of CMF/CMC films are as high as 165 MPa and 13 GPa, respectively. The oxygen transmission rate of CMF/CMC film at DS 0.45 is as low as 0.0161 cm3 μm m−2 day−1 kPa−1 at 0 % relative humidity. In contrast to CMF/CMC in sodium form (Na-CMF/CMC), CMF/CMC in hydrogen form (H-CMF/CMC) make films with improved wet strength without sacrificing transparency. Transparent CMF/CMC films can be used in areas such as disappearing packaging, wound dressing, and moisture sensing.

Facile fabrication of superhydrophobic paper with improved physical strength by a novel layer-by-layer assembly of polyelectrolytes and lignosulfonates-amine

Interest in superhydrophobic paper is growing, and efforts have been made to prepare superhydrophobic paper with an improved physical strength property. This study reported a facile method for fabricating a superhydrophobic paper with enhanced physical strength through layer-by-layer self-assembly of poly(allylamine hydrochloride) (PAH) and lignosulfonates-amine (LSA) on cellulose fiber surfaces, followed by a heat treatment at 160 °C for 30 min. The formation of PAH/LSA multilayers on cellulose fiber surfaces was confirmed by X-ray photoelectron spectroscopy (XPS), zeta potential measurement and atomic force microscopy (AFM). The XPS results showed that the contents of the two characteristic elements (i.e., Cl and S) increased with increasing bilayer numbers. The zeta potential of modified fibers was regularly inversed after each layer deposition. The AFM phase image revealed that the surface root-mean-square roughness of modified cellulose increased along with the increasing bilayer number. Moreover, the wetting properties and physical strength of handsheets prepared from modified cellulose fibers with and without heat treatment were tested, respectively. The result showed that the water contact angle was higher when LSA was in the outermost layer than when PAH was in the outermost layer, and the heat treatment improved the hydrophobicity for all the handsheets. The non-heat-treated handsheet prepared from (PAH/LSA)5 multilayer-modified fibers gave a water contact angle of 120.3o, and then after heat treatment, the contact angle reached up to 151.7o, indicating that high temperature treatment induced the most hydrophobic long chain groups in LSA macromolecules orientated to the multilayer-air interface. The tensile strength properties of both non-heat-treated and heat-treated handsheets made from PAH/LSA-modified fibers were significantly enhanced. When a (PAH/LSA)5 multilayer was deposited on the cellulose fiber surface, the tensile strength increased by 33.9 % for non-heat-treated handsheets and by 57.8 % for heat-treated handsheets compared to that of handsheets made from original fibers, respectively.

UV Radiation of Cellulose Fibers and Acrylic Acid Modified Cellulose Fibers for Improved Stiffness in Paper

In this study, the strength and stiffness was measured on paper sheets with and without acryl ester functionalization grafted with UV-reactive molecules. Three different monomers with one, two, and three UV-reactive groups, respectively, were reacted with the unsaturated ester. The tri-functional monomer had the most influence on the strength properties of the three monomers and was added in concentrations of 5 to 20 wt% of paper (0.03-0.11 mol eq./AGU). The strength and stiffness properties were measured with tensile tests. An increase in elongation, tensile index, and Young’s modulus was seen after irradiation. However, the paper sheets esterified with acrylic acid prior to radiation showed no improvement in stiffness compared to a non-treated paper. As a result, the esterification with acrylic acid to enhance the grafting effect did not have the ability to compensate for the loss in strength caused by the esterification treatment.

Preparation of grafted cationic polymer/silver chloride modified cellulose fibers and their antibacterial properties

ABSTRACTIn this article, we present a simple method for synthesizing antibacterial cellulose fibers that were modified with a cationic polymer and immobilized silver chloride (AgCl) particles. Relatively simple techniques of graft polymerization and onsite precipitation were used to fabricate the composites. Scanning electron microscopy images, Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, and energy‐dispersive X‐ray spectroscopy confirmed the immobilization of the AgCl particles. The observed inhibition zone of the immobilized AgCl particle composites indicated that the biocidal silver ions were released from the composites in aqueous solution. Compared with cationic‐polymer‐grafted cellulose fibers or AgCl alone, the cationic polymer/AgCl composites showed excellent antibacterial activity against Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42092.

Surface Functionalization of Cellulose Fibers Extracted from Juncus Acutus L Plant: Application for the Adsorption of Anionic Dyes from Wastewaters

New amine-functionalized adsorbent was prepared by chemical modification of cellulose fibers extracted from Juncus acutus L (Smar) plants in order to be used as chelating support for the removal of copper ions (Cu (II)). Evidence of grafting DiEthyleneTriamine (DET) onto the raw Smar fibers was provided by nitrogen analysis and Fourier Transform Infrared (FTIR) spectra study. The ability of the binary system [Cu(II)/DET-Smar] for binding Acid Blue 25 (AB25) was then investigated in batch process. Equilibrium data were analyzed by Langmuir, Freundlich and Jossens models. The obtained results reveal that the adsorption of AB25 onto [Cu (II)/DET-Smar] complex show good compliance with the Jossens isotherm. Various thermodynamic activation parameters were estimated and it was found that the adsorption was spontaneous and follows an exothermic process.

Microfluidized carboxymethyl cellulose modified pulp: a nanofibrillated cellulose system with some attractive properties

A method (Ankerfors and Lindstrom in Method for providing nanocellulose comprising modified cellulose fibers, 2009) was employed to physically attach anionic carboxymethyl cellulose (CMC) chains onto wood pulp, upon which it was fibrillated by a microfluidizer-type homogenizer at high applied pressures and at dilute conditions [<3 % (w/w)]. It was found that the CMC-modified pulp can be fibrillated at the same consistencies as many of the commercially available NFC products. The NFC manufacturing process was also deemed to be energy efficient, as it lacked the need for mechanical pre-treatment, which is often a prerequisite for the production of many existing NFC systems. The CMC-based NFC was studied with respect to the rheological characteristics, and was also characterized using AFM-imaging. Further, The NFC was made into films, and its tensile strength was determined together with its barrier properties. In general, the rheological characteristics (viscosity and storage modulus) together with the tensile strength and oxygen barrier properties of the films were improved with increasing the number of passes through the microfluidizer. The fibrillated CMC-modified pulp was found to be as efficient as other NFC systems when employed as dry strength additive. The employment of the investigated material, which can be produced at acceptable costs and through environmentally benign and industrially relevant processes can, hence, potentially lead to significant future savings in the energy consumption levels in the paper and cardboard manufacturing processes, which have been recognized as major application areas of NFC products.

Bio-catalytic action of twin-screw extruder enzymatic hydrolysis on the deconstruction of annual plant material: Case of sweet corn co-products

A continuous process combining an alkaline thermo-mechano-chemical pretreatment neutralization step, followed by injection of enzymes into the twin-screw extruder, was developed using sweet corn co-products as a biomass model. The implementation of the continuous process is described. Particular attention is paid to the influence of the bio-catalytic action of enzymatic hydrolysis on the deconstruction of annual plant material in the twin-screw extruder (a process called “bioextrusion”). The use of a twin-screw extruder allows working with high consistency (20%), in a high shear environment, for a short time (∼2min). In the present work, the nature of the ligno(hemi)cellulosic material transformations, covering solubilization and extraction of saccharides and modification of cellulosic fibers, were investigated. 41% of hemicelluloses and 14% of lignin are extracted by the alkaline pretreatment. Hydrolytic enzymes are not deactivated during bioextrusion, which has a destructing effect on the fiber. It leads to a change of rheological properties and induces an increase of sugars released in the form of mono and polysaccharides (up to 13%/DM of total sugars) with longer chains than in the case of a batch reactor. At the same time, the degree of polymerization decreases and a shortening of the cellulose chains occurs.

Antibacterial modification of cellulosic materials

The proliferation of bacteria on the surfaces of cellulosic materials during their use and storage can have negative effects on the materials themselves and on consumers. People’s demands for materials with antibacterial properties have been satisfied in recent years because of the emergence of various antibacterial compounds. This paper reviews recent research and development progress in antibacterial modification of cellulosic fibers using various biocides such as N-halamines, quaternary ammonium salts, chitosan, triclosan, and nanoparticles composed of noble metals and metal oxides. Antibacterial mechanisms and treating methods for antibacterial cellulosic materials are also involved in this paper.

Photo-induced changes and contact relaxation of the surface AC-conductivity of the paper prepared from poly(ethyleneimine)–TiO2–anthocyanin modified cellulose fibers

Poly(ethyleneimine)–TiO2–anthocyanin modified cellulose fiber sheets were prepared as a support material for dye-sensitized solar cells. The study is focused on the effects of different anthocyanins on the photo-induced changes and contact relaxation of the surface AC-conductivity of the papers. The anthocyanins were extracted from purple cabbage, beet-root, plum peel, red vine and red currant juice. The results showed that there were pronounced contact relaxation effects at the interfaces between alumina electrode and the papers, which were further affected by the presence of anthocyanins. The electrode effects are mainly manifested by a decrease in conductance, which falls by about 30 % from its initial value about 400 min after the beginning of the experiment carried out in the dark. The illumination of the samples induces an increase in the magnitude of the observed changes in conductance but does not affect the nature of the relaxation processes. By estimating the temperature coefficients of conductivity of the papers and the changes in temperature during the illumination of the samples, we succeeded to separate the effects of heating from the total effects of illumination on the conductance and susceptance of the papers.

Effect of silver on cellulose fibre colour

Silver nanoparticles were embedded into cellulose fibres using N‐methylmorpholine N‐oxide as a direct cellulose solvent that was also the system from which silver nanoparticles were generated. The process of generation of silver nanoparticles in the N‐methylmorpholine N‐oxide enables the properties of cellulose fibres to be modified without any additional reducing agent, which makes this process more environmentally friendly. By varying the reaction time of the precursor with the N‐methylmorpholine N‐oxide, a range of nanoparticle sizes was obtained. The fibres contain the same concentration of silver, but, on account of the varying morphology of the nanoparticles, they show a range of colour shades. The primary aim of this study was to show how temperature and reaction time affect the basic parameters of the obtained nanoparticles (shape, size, and distribution in the polymer matrix of fibres), which consequently influences the colour of the modified cellulose fibres. Nanoparticles were characterised by dynamic light scattering and transmission electron microscopy methods, while the fibre hues were estimated by colorimetric analysis. Trichromatic coordinates of colour x, y were delineated, and the colour was identified by positioning the x and y values in the CIE chromaticity diagram. It is noted that many parameters, especially the diameter and shape of the silver nanoparticles, influence the colour of the fibre obtained.