Modified Cellulose Fibers Research Articles

Modified cellulose fibres for adsorption of organic compound in aqueous solution

This paper presents the results of an experimental study of removal of organic contaminant from wastewater using chemically modified cellulose fibres. The adsorption capacities of the modified fibres towards various organic molecules were investigated. The ensuing modified fibres appeared to be efficient absorbent for different dissolved organic molecules in water. The recycling tests revealed that the exhausted substrates could be regenerated without loosing their capacity. The adsorption isotherm related to different solutes follows the Langmuir model in entire range of concentration. To confirm the possibility of using the modified cellulose fibres as a sorbent for the removal of dissolved organic pollutant, adsorption breakthrough curves were established under different operating condition such as concentration, flow rate and the column length. The main advantage of this substrate lies in its relative facile regeneration without a significant loss of its adsorption capacity.

Modified cellulose fibres for adsorption of dissolved organic solutes

Cellulose fibres were grafted with aliphatic anhydrides having C6, C8, C12 and C16 chain length using a heterogeneous solvent exchange acylation procedure. The ensuing materials were fully characterised by FTIR, solid state 13C-NMR, Wide-angle X-ray scattering and contact angle measurements. These techniques showed that the chemical coupling has indeed occurred. The prepared modified fibres appeared to be efficient to trap different organic molecules dissolved in water. Recycling tests revealed that the saturated substrates could be regenerated tens of times without loosing their capacity of absorption of organic contaminants.

Controlled heterogeneous modification of cellulose fibers with fatty acids: Effect of reaction conditions on the extent of esterification and fiber properties

AbstractThe controlled heterogeneous partial modification of cellulose fibers with fatty acids, partially preserving the fiber structure, was investigated. The effect of reaction conditions, such as reaction time, fatty acid chain length, and solvent types (swelling and non swelling), on the extent of esterification and fiber properties was evaluated by elemental analysis, IR‐ATR, X‐ray diffraction, 13C CPMAS NMR, contact angle measurement, thermogravimetry, and scanning electron microscopy. The degree of substitution (DS) increased with reaction time and with the swelling effect of the reaction medium and decreased with the fatty acids chain length. Higher the DS, higher is the decrystallization of cellulose as a result of the heterogeneous esterification reaction. The esterification with fatty acids enhanced the hydrophobic character of the fibers, but decreased their thermal stability. These properties are not strongly affected by the DS in the range investigated, viz. up to 1.4. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1093–1102, 2006

Textile Processing for Modification of Cellulose Fiber

Textile Processing for Modification of Cellulose Fiber

Modification of cellulose fibers with functionalized silanes: Effect of the fiber treatment on the mechanical performances of cellulose–thermoset composites

AbstractUnsaturated polyester and epoxy resin matrices were filled with silane‐treated cellulose fibers and the ensuing composites were tested in terms of mechanical properties before and after accelerated aging consisting of their immersion into water. The coupling agents used were γ‐aminopropyltriethoxysilane (APS), γ‐methacrylopropyltrimethoxysilane (MPS), hexadecytrimethoxysilane, and γ‐mercaptopropyltrimethoxysilane (MRPS) and those containing reactive functions capable of reacting at one end with the fibers and at the other with the matrix, namely, APS, MPS, and MRPS, were more efficient in improving the mechanical properties of the composites. The immersion into water induced a drastic loss of mechanical properties of the materials. The water uptake of the composites was also studied and showed that the silane treatment was poorly efficient in preventing cellulose from water absorption. The fracture surfaces were inspected by scanning electron microscopy, which confirmed the quality of the interface. These observations were in agreement with the results obtained from the dynamic mechanical characterization. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 974–984, 2005

Surface modification of cellulose fibres

Several approaches to the modification of cellulose fibres are described, namely: (i) physical treatments such as corona or plasma treatments under different atmospheres; (ii) grafting with hydrophobic molecules using well-known sizing compounds; (iii) grafting with bi-functional molecules, leaving one of the functions available for further exploitation; and (iv) grafting with organometallic compounds. The modified surfaces were characterized by elemental analysis, contact angle measurements, inverse gas chromatography, X-ray photoelectron and infrared spectroscopy, wettability, etc. These different tools provided clear-cut evidence of the occurrence of chemical reactions between the grafting agent used and the hydroxy functions of the cellulose surface, as well as of the existence of covalent bonding in the ensuing composite materials between the matrix and the fibres through the use of doubly reactive coupling agents.

Spectroscopic Studies of the Intermolecular Interactions of Congo Red and Tinopal CBS with Modified Cellulose Fibers

The adsorption of Congo red and tinopal CBS dyes on cellulose fibers was investigated using electronic absorption and fluorescence spectroscopies. Hydrogen bonds appear to be relevant for the dye-fiber interactions as indicated by the solvatochromism of Congo red in water, methanol, and dimethyl sulfoxide solutions, and when adsorbed on cellulose fibers. We also demonstrate that electrostatic interactions play an important role in the dye-medium interaction, through the analysis of absorption spectra of Congo red and fluorescence spectra of tinopal in aqueous solutions containing salt and in layer-by-layer nanostructured films with poly(allylamine hydrochloride). For instance, dye adsorption was enhanced when salt was added to the dipping solution, which was explained by the synergistic effect between the conformational changes of the cellulose and changes in the solvation layer around the cellulose chains and around dye molecules. On the basis of the fluorescence results for tinopal CBS, we inferred that dye aggregation is not relevant for adsorption on the fibers. In addition, fluorescence spectroscopy is proven very sensitive for studying the organization of dye molecules in layer-by-layer films, particularly those undergoing irreversible structural changes.

Modification of cellulose fiber with silk sericin

AbstractCellulose fiber surface was modified with silk sericin (or simply, sericin). Sericin fixation on cellulose was confirmed by environmental scanning electron microscopy (ESEM) and Fourier transform infrared spectrophotometry–attenuated total reflectance (FTIR‐ATR). Sericin content in finished samples was estimated by dyeing treated fabrics with an acid dye, Supranol Bordeaux B, and determining K/S and L values of the dyed fabrics. The treated fabrics were tested for free formaldehyde content, crease recovery, tensile strength, electrical resistance, water retention, and biocidal activity. From ESEM and FTIR‐ATR results, it was found that sericin coated onto cotton surfaces as a film. Increasing sericin content in the finishing solution increased the amount of coated sericin, and a greater depth of color in dyed samples and reduced free formaldehyde content in treated samples were observed. The sericin content in samples was found to have a negligible influence on tensile strength and crease recovery angle. With increasing sericin content, electrical resistivity of the samples dramatically decreased and water retention increased, indicating that sericin‐treated fabrics may be comfortable to wear because of its maintenance of moisture balance with respect to human skin. Because cotton textile coated with sericin exhibited low formaldehyde content and no biocidal activity against Klebsiella pneumoniae and Staphylococcus aureus, the fabric may reduce skin irritation and disturbance of physiological skin flora arising from textile contact. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1421–1428, 2005

Cellulosics modified with slow-release reagents. Part I. Synthesis of triazine-anchored reagents for slow release of active substances from cellulosic materials

Novel tri-functional triazines for the modification of cellulosic fibers are prepared from cyanuric chloride. The compounds employ a monochlorotriazinyl (MCT) anchor group for fixation, an active substance showing slow release properties, and a reactivity tuner to facilitate release control. While the compounds are completely stable under dry conditions, the active substances are released simply by surrounding humidity. The reagents offer intriguing perspectives for the preparation of modified cellulosics for single-use application in fields such as healthcare, cosmetics, or personal hygiene.

Modified Cellulose Fibers as Reinforcing Fillers for Macromolecular Matrices

AbstractVarious 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.

The surface modification of cellulose fibres for use as reinforcing elements in composite materials

The interest in using cellulose fibres as reinforcing elements in composite materials based on polymeric matrices is constantly growing, mainly because of the many advantages associated with this renewable material. However, the preparation of cellulose-based composites is perturbed by the highly hydrophilic character of the fibres, which is associated with a low interfacial compatibility with hydrophobic polymeric matrices, as well as with a loss of mechanical properties after moisture uptake. In order to reduce the hydrophilic character of cellulose fibres and to improve the strength of their adhesion to the matrix, it is necessary to undertake a structural modification of their surface. Several approaches have been studied, namely (i) physical treatments such as corona, plasma, laser, vacuum ultraviolet and γ-radiation treatments; (ii) chemical grafting by direct condensation, including surface compatibilisation with hydrophobic moieties and co-polymerisation with the matrix. The copolymerisation approach called upon different strategies: (i) The use of bi-functional molecules capable of reacting with the OH groups of the cellulose surface and leaving the second functions available for further exploitation; (ii) The direct activation of the surface and the subsequent graftingfrom polymerisation; and (iii) The condensation of organometallic compounds, followed by their coupling with suitable reactive molecules or macromolecules. The characterisation of the modified surfaces involved a variety of techniques, including elemental analysis, contact angle measurements, inverse gas chromatography, X-ray photoelectron and FTIR spectroscopy, water uptake, etc. The present survey reviews the different approaches proposed in the literature and critically assesses their respective merits and drawbacks.

Surface modification of cellulose fibers: towards wood composites by biomimetics

A biomimetic approach was taken for studying the adsorption of a model copolymer (pullulan abietate, DS 0.027), representing the lignin–carbohydrate complex, to a model surface for cellulose fibers (Langmuir–Blodgett thin films of regenerated cellulose). Adsorption results were assayed using surface plasmon resonance spectroscopy (SPR) and atomic force microscopy (AFM). Rapid, spontaneous, and desorption-resistant surface modification resulted. This effort is viewed as a critical first step towards the permanent surface modification of cellulose fibers with a layer of molecules amenable to either enzymatic crosslinking for improved wood composites or thermoplastic consolidation. To cite this article: S.E. Gradwell et al., C. R. Biologies 327 (2004).

Modification of cellulose fibres with organosilanes: Under what conditions does coupling occur?

Different cellulose substrates and organosolv lignin were treated heterogeneously with organic solutions of trialkoxysilanes bearing variable function on the forth substituent. It was shown unambiguously for the first time that SiOR does not react with the hydroxy groups of cellulose even at high temperature, whereas it condenses with the phenolic OH of lignin. The addition of moisture to these systems induces the partial hydrolysis of the siloxane moieties and the ensuing silanol groups can then react with the cellulose OH, but only at high temperature. Using the latter systems and a siloxane bearing a polymerizable function, it was possible to attach poly(methylmethacrylate) chains to the surface of cellulose fibres through a two-step procedure.

Modification of cellulosic fibres with functionalised silanes: development of surface properties

The surface modification of cellulosic fibres was carried out using organofunctional silane coupling agents in an ethanol/water medium. A heat treatment (curing) was applied after reaching the equilibrium adsorption of the prehydrolysed silanes onto the cellulosic substrate. The modified fibres were then characterised by diffuse reflectance infrared spectroscopy and contact angle measurements. The presence of Si–O–Cellulose and Si–O–Si bonds on the cellulose surface confirmed that the silane coupling agent was efficiently held on the fibres surface through both condensation with cellulose hydroxyl groups and self-condensation between silanol groups. The change of the surface properties after the modification was ascertained by contact angle measurements and inverse gas chromatographic analysis. It was shown that the silane functional groups appended to the fibre surface could participate in the chain growth of appropriate monomers to give a covalent continuity between the fibres and the ensuing polymer matrix.

Cellulose fiber/poly(ethylene-co-methacrylic acid) composites with ionic interphase

Abstract Cellulose fiber/thermoplastic composites with ionic interphase were prepared from modified cellulose fibers and poly(ethylene-co-methacrylic acid) (PE-co-MA). The cellulose fiber was treated by using coupling agent or sodium hydroxide followed by introduction of ionic quaternary ammonium groups on the fiber surface, which was then compounded with the polymer having anionic groups. The effect of the ionic interface on the composite physical and thermal dynamic properties was investigated. An obvious improvement in mechanical strength of the ionic-interface composites was observed due to acid–base interactions. The improved adhesion could be ascribed to the interaction between cationic grafted groups at the cellulose fiber surface and the anionic groups in the PE-co-MA.

Surface Flocculation as a New Tool for Controlling Adsorption Processes

The dyeing of modified pulp, particularly with regard to the mechanism involved, was studied. The reaction mechanism for the modification of cellulose fibres in aqueous solution by cationic agents was also described. The results obtained were expressed in the form of adsorption isotherms. The capture of molecules, colloidal particles, etc. during the adsorption processes involving modified pulp could be explained by two possible mechanisms: (i) aggregation (coagulation or flocculation) in solution followed by adsorption and (ii) surface aggregation (coagulation or flocculation). Surface aggregation appeared to be the most likely for pulp with a low degree of modification. The typical Langmuir adsorption isotherm correlated the data obtained for unmodified pulp very well.

Modified cellulose fibers prepared by the N‐methylmorpholine‐N‐oxide (NMMO) process

AbstractCellulose fibers with modified properties have been prepared from cellulose solutions in N‐methylmorpholine‐N‐oxide (NMMO). Poly(ethylene oxide) as a hydrophilic modifier and polyethylene as a hydrophobic modifier were added to the spinning solution. Based on microscope examination and measurements of such properties of fibers as porosity, moisture absorption, water retention, and tensile strength, structural changes as well as physical and mechanical properties of the resultant fibers depending on the amount of modifier added to the spinning solution were analyzed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 907–916, 2002

Studies on topochemical modification of cellulosic fibres

Studies on topochemical modification of cellulosic fibres

Recent Contributions to the Preparation of Polymers Derived from Renewable Resources

The aim of this paper is to provide an update on the ongoing research of our laboratory in the field of polymeric materials derived from biomass components. The first section deals with the oxypropylation of different vegetable or animal biomass residues and the use of the ensuing polyols in different polyurethane formulations. Thus, foams, elastomers, and membranes were obtained and their properties compared favorably with those of equivalent materials prepared from petroleum-based sources. The second section is devoted to furan copolymers and their use in reversibly crosslinked elastomers via the Diels–Alder reaction and in the field of photosensitive materials. The third section describes novel approaches to the surface modification of cellulosic fibers to be employed in composite materials with polymeric matrices, consisting in the use of organometallics and siloxanes as coupling agents. The final two sections are devoted to a brief outline of the role of lignins and vegetable oils as additives in printing inks, varnishes, and paints.

Surface chemical modification of natural cellulose fibers

AbstractSimple esterification and etherification reactions were applied to steam‐exploded Flax (Linum usitatissimum) with the aim of changing the surface properties through modification of fiber surface chemistry. Native and chemically modified cellulose fibers were characterized in terms of thermal stability, surface chemistry, morphology, and crystal structure. Independent of the substituent nature, chemically modified fibers exhibited a thermal stability comparable to that of native cellulose. Introduction of the desired chemical groups at the fiber surface was demonstrated by TOF‐SIMS analysis, whereas FTIR showed that the substitution reaction involved only a small fraction of the cellulose hydroxyls. No change of the native crystalline structure of cellulose fibers was caused by chemical modification, except in the case where ether substitution was carried out in water‐isopropanol medium. Cellulose fibers with unchanged structure and morphology and carrying at the surface the desired chemical groups were obtained for reinforcing applications in polymer composites. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 38–45, 2002