The Experts below are selected from a list of 1086 Experts worldwide ranked by ideXlab platform
F. Carrillo - One of the best experts on this subject based on the ideXlab platform.
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properties of regenerated cellulose Lyocell fiber reinforced composites
Journal of Reinforced Plastics and Composites, 2010Co-Authors: F. Carrillo, X Colom, X CanavateAbstract:Properties of composites based on short regenerated cellulose Lyocell fibers as a reinforcement and high-density polyethylene (HDPE) matrix were analyzed in this study. The effect of the fiber content and chemical pre-treatments (silane coupling agent, grafting of polymethyl metacrylate, PMMA) on composite mechanical and physical properties were investigated by mechanical tensile testing, water absorption test and fracture surface microstructure analysis. Mechanical tensile test indicated that fiber-reinforced composites show higher modulus than pure HDPE. In addition, silane and grafting (with PMMA) treatments of Lyocell fibers resulted in a significant increase of the Young’s modulus. Also, the effect of silane pre-treatment on fiber—matrix adhesion resulted in better mechanical properties when treatment was performed on Lyocell fibers compared with flax fibers (used as reference fibers). Moreover, it was observed that the tensile strength of composites with a fiber content higher than 13.8% lay below t...
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surface modification of Lyocell fibres by graft copolymerization of thermo sensitive poly n isopropylacrylamide
European Polymer Journal, 2008Co-Authors: F. Carrillo, Oris Defays, X ColomAbstract:Abstract Thermo-sensitive poly- N -isopropylacrylamide (poly-NIPAAm) was grafted onto Lyocell fibres using cerium ammonium nitrate (CAN) as initiator. The effects of initiation time, initiator concentration, monomer concentration and grafting time on the degree of grafting were investigated. A 15–60 min exposure time, 7.5 mM CAN solution concentration and a 0.5–1 mM NIPAAm monomer concentration were optimal for obtaining a maximum degree of grafting (60–70% at 24 h grafting time) of poly-NIPAAm on Lyocell fibres. Higher degree of grafting was obtained increasing the grafting time, such as 120% at 72 h. The properties of the obtained poly-NIPAAm/Lyocell copolymer were also investigated. Specifically, the effects of temperature and degree of grafting of poly-NIPAAm on the swelling behaviour of the copolymer were experimentally determined. Moreover, structural characterization, thermal behaviour and morphology of the poly-NIPAAm/Lyocell copolymers were examined by Fourier Transform Infrared Spectroscopy (FTIR), Differencial Scanning Calorimetry (DSC) and Scanning electron microscopy (SEM) techniques, respectively.
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structural ftir analysis and thermal characterisation of Lyocell and viscose type fibres
European Polymer Journal, 2004Co-Authors: F. Carrillo, Xavier Colom, J J Sunol, J SaurinaAbstract:The microstructure and thermal properties of Lyocell and other regenerated cellulose fibres (viscose and modal) were analysed using DSC, TG and FTIR. The FTIR spectral analysis showed that Lyocell is the most crystalline fibre and is composed principally of crystalline cellulose II and amorphous cellulose. Likewise, the thermal analysis showed that Lyocell has a higher thermal stability than viscose and modal fibres, as the difference between the onset temperature for its decomposition process was as high as 20 °C.
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cellulase processing of Lyocell and viscose type fibres kinetics parameters
Process Biochemistry, 2003Co-Authors: F. Carrillo, X Colom, M Lopezmesas, Manuel Jose Lis, F Gonzalez, J ValldeperasAbstract:Abstract Differences in hydrolysis behaviour between Lyocell and viscose type regenerated celluloses (viscose and modal) have been evaluated by the study of the enzymic hydrolysis by cellulases. Kinetic parameters (V em and k e ) and enzyme catalytic specificity were calculated during cellulase processing. The results show low adsorption, catalytic specificity and rate of hydrolysis (V em =0.407 h/l h) of Lyocell fibres ahead of the viscose-type fibres due to their higher orientation and crystallinity. Fibrillation treatment of Lyocell favours cellulase attack by greatly increasing the availability of sites for enzyme adsorption.
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Crystallinity changes in Lyocell and viscose-type fibres by caustic treatment
European Polymer Journal, 2002Co-Authors: Xavier Colom, F. CarrilloAbstract:One of the most important treatments performed on cellulosic fibres to improve properties such as dimensional stability, tensile strength and lustre, is mercerisation. The aim of this work was to study the crystallinity, accessibility and unit cell structure changes occurring in three types of regenerated cellulose fibres (Lyocell, modal and viscose) that were mercerised with caustic soda solutions of different concentrations. Differences were observed between the behaviour of the viscose type fibres (viscose and modal) and that of the Lyocell fibres. For the viscose type fibres, the proportion of crystalline regions increased at low alkali concentrations, while for Lyocell fibres a decrease in crystallinity was observed. In all three fibres there was a transformation from cellulose II to amorphous cellulose. While for Lyocell the transformation was partial, the modal and in particular the viscose fibres showed a complete transformation, and the swelling agent caused the fibre to dissolve at high caustic concentrations.
Herbert Sixta - One of the best experts on this subject based on the ideXlab platform.
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ioncell f ionic liquid based cellulosic textile fibers as an alternative to viscose and Lyocell
Textile Research Journal, 2016Co-Authors: Anne Michud, Marjaana Tanttu, Shirin Asaadi, Eveliina Netti, Pirjo Kaariainen, Anders Persson, Anders Berntsson, Michael Hummel, Herbert SixtaAbstract:Ioncell-F, a recently developed process for the production of man-made cellulosic fibers from ionic liquid solutions by dry-jet wet spinning, is presented as an alternative to the viscose and N-methylmorpholine N-oxide (NMMO)-based Lyocell processes. The ionic liquid 1,5-diazabicyclo[4.3.0]non-5-ene acetate was identified as excellent cellulose solvent allowing for a rapid dissolution at moderate temperatures and subsequent shaping into continuous filaments. The highly oriented cellulose fibers obtained upon coagulation in cold water exhibited superior tenacity, exceeding that of commercial viscose and NMMO-based Lyocell (Tencel®) fibers. The respective staple fibers, which have been converted into two-ply yarn by ring spinning technology, presented very high tenacity. Furthermore, the Ioncell yarn showed very good behavior during the knitting and weaving processes, reflecting the quality of the produced yarn. The successfully knitted and woven garments from the Ioncell yarn demonstrate the suitability of...
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sulfur free dissolving pulps and their application for viscose and Lyocell
Cellulose, 2011Co-Authors: Gabriele Schild, Herbert SixtaAbstract:In this study, the concept of multifunctional alkaline pulping has been approved to produce high-purity and high-yield dissolving pulps. The selective removal of hemicelluloses was achieved by either water autohydrolysis (PH) or alkaline extraction (E) both applied as pre-treatments prior to cooking. Alternatively, hemicelluloses were isolated after oxygen delignification in a process step denoted as cold caustic extraction (CCE). Eucalyptus globulus wood chips were used as the raw material for kraft and soda-AQ pulping. In all process modifications sulfur was successfully replaced by anthraquinone. By these modifications purified dissolving pulps were subjected to TCF bleaching and comprehensive viscose and Lyocell application tests. All pulps met the specifications for dissolving pulps. Further more, CCE-pulps showed a significantly higher yield after final bleaching. Morphological changes such as ultrastructure of the preserved outer cell wall layers, specific surface area and lateral fibril aggregate dimension correlated with the reduced reactivity towards regular viscose processing. The residual xylan after alkali purification depicted a lower content of functional groups and a higher molecular weight and was obviously entrapped in the cellulose fibril aggregates which render the hemicelluloses more resistant to steeping in the standard viscose process. Simultaneously, the supramolecular structure of the cellulose is partly converted from cellulose I to cellulose II by the alkaline purification step which did not influence the pulps reactivity significantly. Nevertheless, these differences in pulp parameters did not affect the Lyocell process due to the outstanding solubility of the pulps in NMMO. Laboratory spinning revealed good fiber strength for both, regular viscose and Lyocell fibers. The high molecular weight xylan of the CCE-treated pulps even took part in fiber forming.
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sulfur free dissolving pulps and their application for viscose and Lyocell
Cellulose, 2011Co-Authors: Gabriele Schild, Herbert SixtaAbstract:In this study, the concept of multifunctional alkaline pulping has been approved to produce high-purity and high-yield dissolving pulps. The selective removal of hemicelluloses was achieved by either water autohydrolysis (PH) or alkaline extraction (E) both applied as pre-treatments prior to cooking. Alternatively, hemicelluloses were isolated after oxygen delignification in a process step denoted as cold caustic extraction (CCE). Eucalyptus globulus wood chips were used as the raw material for kraft and soda-AQ pulping. In all process modifications sulfur was successfully replaced by anthraquinone. By these modifications purified dissolving pulps were subjected to TCF bleaching and comprehensive viscose and Lyocell application tests. All pulps met the specifications for dissolving pulps. Further more, CCE-pulps showed a significantly higher yield after final bleaching. Morphological changes such as ultrastructure of the preserved outer cell wall layers, specific surface area and lateral fibril aggregate dimension correlated with the reduced reactivity towards regular viscose processing. The residual xylan after alkali purification depicted a lower content of functional groups and a higher molecular weight and was obviously entrapped in the cellulose fibril aggregates which render the hemicelluloses more resistant to steeping in the standard viscose process. Simultaneously, the supramolecular structure of the cellulose is partly converted from cellulose I to cellulose II by the alkaline purification step which did not influence the pulps reactivity significantly. Nevertheless, these differences in pulp parameters did not affect the Lyocell process due to the outstanding solubility of the pulps in NMMO. Laboratory spinning revealed good fiber strength for both, regular viscose and Lyocell fibers. The high molecular weight xylan of the CCE-treated pulps even took part in fiber forming.
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instabilities in the system nmmo water cellulose Lyocell process caused by polonowski type reactions
Holzforschung, 2002Co-Authors: Thomas Rosenau, Andreas Hofinger, Antje Potthast, Herbert Sixta, Paul KosmaAbstract:Polonowski type degradation reactions arc a major reason for the frequently observed instability of solutions of cellulose in N-methylmorpholine-N-oxide monohydrate (NMMO. 1). The degradation is induced by degradation products of cellulose and NMMO generated in situ in the Lyocell system. The presence of both an amine component such as morpholine or N-methylmorpholine, and an acid component is required for the decomposition process to proceed. The latter might be a low-molecular-weight compound, such as formic acid, acetic acid or gluconic acid, or also a high-molecular-weight acid, such as polyglucuronic acid or ion exchange resin.
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the chemistry of side reactions and byproduct formation in the system nmmo cellulose Lyocell process
Progress in Polymer Science, 2001Co-Authors: Thomas Rosenau, Antje Potthast, Herbert Sixta, Paul KosmaAbstract:Abstract N -Methylmorpholine- N -oxide monohydrate (NMMO) is used as a solvent for direct dissolution of cellulose in industrial fiber-making (Lyocell process). Ideally, Lyocell fiber production per se should be an entirely physical process that does not cause chemical changes in pulp or solvent. However, there are several side reactions and considerable byproduct formation in the system cellulose/NMMO/water which can cause detrimental effects, such as degradation of cellulose, temporary or permanent discoloration of the resulting fibers, decreased product performance, pronounced decomposition of NMMO, increased consumption of stabilizers, or even thermal runaway reactions. The present paper will focus on chemical aspects of the system NMMO/cellulose. After a short section on Lyocell fiber production, the analytical techniques to monitor side reactions in the Lyocell system will be discussed. In the main part, the side reactions of NMMO in the Lyocell process have been divided into homolytic (radical) and heterolytic (non-radical) processes in a systematic investigation. In all homolytic reactions of NMMO, cleavage of the N–O bond with formation of an aminium (aminyl) radical is the first step. Formation, properties and subsequent reactions of this primary radical species will be summarized. In the absence of oxygen, the radical undergoes disproportionation or other redox processes that finally produce N -methylmorpholine, or morpholine and HCHO, respectively. In contrast, reactions of C-centered tautomers of the radical with dioxygen dominate in the presence of oxygen. Also the effects of transition metal ions, which are potent inducers of homolytic reactions of NMMO, are described. Heterolytic reactions in the Lyocell system proceed according to three major pathways. First, reductive deoxygenation of NMMO produces N -methylmorpholine with concomitant oxidation of available reductants, e.g. cellulose or carbohydrate model compounds. Second, Polonowski type reactions, which are intramolecular redox processes, finally generate morpholine and formaldehyde. In a third pathway, an autocatalytic process induced by carbonium–iminium ions can cause quantitative decomposition of NMMO. The formation and determination of reactive intermediates and heterolytic degradation products as well as their role in the system is analyzed. Furthermore, thermal degradation reactions under controlled conditions or under conditions leading to uncontrolled thermal degradation, i.e. explosions or ‘exothermic events’, are considered. Especially the latter processes are important from the viewpoint of system safety since they can be induced by several of the discussed radical and non-radical reactions. The homolytic, heterolytic and thermal degradation reactions in the system cellulose/NMMO/water have been reviewed in terms of reaction mechanisms, byproduct formation, and negative effects on the Lyocell system. Precise knowledge of reaction mechanisms as well as the role of harmful intermediates and products allows for the safe and economical production of Lyocell fibers, and a rational design of chemical stabilizers for the Lyocell system.
Mikael Skrifvars - One of the best experts on this subject based on the ideXlab platform.
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phenyl silane treatment and carding process to improve the mechanical thermal and water absorption properties of regenerated cellulose Lyocell polylactic acid bio composites
Composites Part B-engineering, 2019Co-Authors: Jiwon Park, Jongho Back, Seongwook Jang, Mikael SkrifvarsAbstract:Abstract We fabricated a new composite material with increased Lyocell (a form of rayon that consists of cellulose fiber made from dissolving wood pulp) content through a surface hydrophobic treatment using phenyl silane and fiber carding/melt pressing. A matrix of polylactic acid (PLA) was used to enhance the environment-friendly properties of the composite and a carding process was used to orient the fibers in the composite. The Lyocell content was controlled from 10% to 90%. Cross direction (CD) and machine direction (MD) samples were prepared to confirm the effect of the fiber directionality of the composite on its mechanical properties. The MD samples performed better than the CD samples. The tensile, flexural, and impact strengths of the composite were increased by approximately 85%, 155%, and 55%, respectively, after surface treatment. In the heat-resistance evaluation, confirmed by pyrolysis, surface treatment showed an average improvement of more than 10 °C. The water-absorption characteristics showed dramatic improvement, with enhanced surface-wetting properties and excellent initial moisture-absorption properties in the immersion test. Based on the comprehensive results, we conclude that the performance of the composite was satisfactory even when the content of Lyocell was 50% or more.
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characterisation of polylactic acid biocomposites made from prepregs composed of woven polylactic acid hemp Lyocell hybrid yarn fabrics
Composites Part A-applied Science and Manufacturing, 2016Co-Authors: Behnaz Baghaei, Mikael SkrifvarsAbstract:Abstract This paper describes the mechanical properties and water absorption characteristics for biocomposites made from woven PLA/hemp/Lyocell prepregs. The aim was to improve the properties with the addition of Lyocell fibre into a hybrid yarn. Well-aligned hybrid yarns composed of hemp/PLA, hemp–Lyocell/PLA, respective, Lyocell/PLA were made by wrap spinning. Unidirectional satin fabrics were made by weaving with PLA (warp) and the hybrid yarns (weft). Uniaxial composites were fabricated with 30 fibre mass% using compression moulding. The composites were investigated for tensile, flexural and impact properties. Combining hemp with Lyocell in a PLA matrix improves the mechanical properties, compared to hemp/PLA composites. The composite made from the satin Lyocell/PLA fabric gave the best mechanical properties. The type of fibre reinforcement compositions did not significantly affect the water absorption of the biocomposites. Scanning electron microscopy showed that fibre pull-outs appear more often in hemp/PLA composites than in composites also including Lyocell fibre.
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Effect of alkali and silane surface treatments on regenerated cellulose fibre type (Lyocell) intended for composites
Cellulose, 2015Co-Authors: Sunil Kumar Ramamoorthy, Mikael Skrifvars, Marja RissanenAbstract:Cellulose fibres have significant importance and potential for polymer reinforcement. It is essential to modify the surface of the fibre to obtain good fibre-matrix interface. Surface treatments can increase surface roughness of the fibre, change its chemical composition and introduce new moieties that can effectively interlock with the matrix, resulting in good mechanical properties in the composites. This is mainly due to improved fibre-matrix adhesion. The treatments may also reduce the water absorption rate by converting part of the hydroxyl groups on the fibre surface into other functional groups. Chemical modification of the surface of a regenerated cellulose fibre of the Lyocell type was carried out by alkali and silane treatments, which significantly changed the properties of the Lyocell fibres. Three parameters were considered when the fibre surface treatment was done: concentration (2–15 wt%), temperature (25 and 50 °C) and time (30 min–72 h). Fourier transform infrared spectroscopy and Raman spectroscopy were used for chemical analysis and qualitative analysis of the cellulose crystallinity due to the surface treatments; subsequently, mechanical strength of the fibres was tested by tensile testing. Weight loss, moisture regain and swelling measurements were taken before and after treatments, which showed the obvious changes in fibre properties on treatment. Heat capacity of the fibres was measured for untreated and treated fibres, and thermal degradation of fibres was examined to see the stability of fibres at elevated temperatures. Wettability and surface energies were measured using dynamic contact angle method in three wetting mediums. Scanning electron microscopy was used to study the morphological properties of the fibres.
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Mechanical and thermal characterization of compression moulded polylactic acid natural fiber composites reinforced with hemp and Lyocell fibers
Journal of Applied Polymer Science, 2014Co-Authors: Behnaz Baghaei, Marja Rissanen, Mikael Skrifvars, Sunil Kumar RamamoorthyAbstract:Mechanical and thermal characterization of compression moulded polylactic acid natural fiber composites reinforced with hemp and Lyocell fibers
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biocomposites from regenerated cellulose textile fibers and bio based thermoset matrix for automotive applications
TexComp-11 Conference Leuven Belgium September 16-20 2013, 2013Co-Authors: Sunil Kumar Ramamoorthy, Kayode Adekunle, Chanchal Kumar Kundu, Tariq Bashir, Mikael SkrifvarsAbstract:Biocomposites were produced from regenerated cellulose fiber reinforcement and soybean based bio-matrix. Mechanical, thermal, viscoelastic and morphological results show the good potential of these composites to be used as structural materials in automotive industries. This article focuses on manufacturing and testing of these composites for engineering materials. Regenerated cellulose fibers such as Lyocell and viscose were reinforced in soybean based thermoset matrix to produce composites by compression molding. Hybrid composites were produced by mixing both these fibers at known ratio and the total fiber content in composite was between 40 and 60 weight %. In general, Lyocell based composites showed better tensile properties than viscose based composites. Composites consisting 60 weight % Lyocell and rest with matrix had tensile strength of 135 MPa and tensile modulus of 17 GPa. These composites also showed good flexural properties; flexural strength of 127 Mpa and flexural modulus of 7 GPa. Dynamic mechanical thermal analysis showed that these composites had good viscoelastic properties. Viscose based composites had better percentage elongation during tensile test. These composites also showed relatively good impact and viscoelastic properties. Scanning electron microscope images showed that the composites had good fiber-matrix adhesion. Several efforts are made to produce sustainable biomaterials to replace synthetic materials due to inherent properties like renewable, biodegradable and low density. Biocomposites play significant role in sustainable materials which has already found applications in automotive and construction industries. Many researchers produced biocomposites from natural fiber and bio-based/synthetic matrix and it had found several applications. There are several disadvantages of using natural fiber in composites; quality variation, place dependent, plant maturity, harvesting method, high water absorption etc. These composites also give odor which has to be avoided in indoor automotive applications. These natural fibers can be replaced with lignocelluloses, agro mass and biomass to develop biocomposites as they are from natural origin. Lyocell and viscose are manmade regenerated cellulose fibers which is from natural origin has excellent properties. These fibers can be used as reinforcements to produce biocomposites which can overcome most of the above listed disadvantages of natural fibers. Many composites were made from natural fiber reinforcement and petroleum based synthetic matrix. Researchers have been finding ways to get matrix out of natural resources like soybean and linseed on chemical modifications. This article is focused on producing and testing sustainable material with regenerated cellulose and soybean based bio-matrix for automotive applications.
Thomas Echtold - One of the best experts on this subject based on the ideXlab platform.
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spun dyed Lyocell
Dyes and Pigments, 2007Co-Authors: Avinash P Mania, Hartmu Ruef, Thomas EchtoldAbstract:Abstract Cellulose pulp was dyed with a vat dye in an exhaust dyeing process. The dyed pulp, mixed with undyed pulp, was dissolved in NMMO and spun to obtain ‘spun-dyed’ Lyocell fibers. The dyeing behavior of pulp and fastness properties of the spun-dyed fibers were compared with that of different cellulosic substrates dyed with the same vat dye. The cellulose pulp exhibited the highest degree of dye exhaustion as compared to Lyocell fabrics (woven and knit), yarns, fibers, and woven cotton. The spun-dyed Lyocell fibers exhibited superior light fastness as compared to conventionally dyed cotton and Lyocell substrates. The spun-dyeing process is believed to involve lower costs than conventional dyeing and to be more eco-friendly. The fiber spinning process did not appear to be detrimental to the color in spun-dyed fibers.
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splitting tendency of cellulosic fibers part 1 the effect of shear force on mechanical stability of swollen Lyocell fibers
Cellulose, 2006Co-Authors: Hale Baha Ozturk, Satoko Okubayashi, Thomas EchtoldAbstract:A procedure for splitting of a Lyocell fiber into a multitude of finer fibrils was developed. Crockmeter, usually used for rub-fastness of colored textiles, was modified and used for obtaining required shear force on swollen Lyocell fiber. The shear force applied on fibers, and the concentration of NaOH, which affects swelling degree of fiber, were shown to be the leading parameters determining split number of Lyocell fiber. While number of shear cycles was found to be of minor relevance for fiber splitting, the applied pressure directly influences the number of splitted fibrils. For example, at a pressure of 34.8 kPa, the average split number of Lyocell fiber in 2.5 M NaOH solution was observed as 15, whereas it was observed as 30 for 47 kPa and 41 for 59.3 kPa. Splitting was not observed above 5 M of NaOH solution. Analyses of fiber splitting permit new aspects to study inner structure of Lyocell.
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fibrillation tendency of cellulosic fibers part 3 effects of alkali pretreatment of Lyocell fiber
Carbohydrate Polymers, 2005Co-Authors: Wangsu Zhang, Satoko Okubayashi, Thomas EchtoldAbstract:Abstract The influences of pretreatments with different alkalis on the fibrillation tendency of Lyocell fiber were investigated. The fibril number (FN pre ) decreased after pretreatment in aqueous sodium hydroxide (NaOH) and potassium hydroxide (KOH) solutions at concentrations between 3.0 and 7.0 mol/l, and minimized at 5.0 mol/l. The water retention value of the fiber after the pretreatment (WRV pre ) in NaOH and KOH at the concentration where the FN pre was minimized was 0.66 cm 3 /g. Contrarily, the FN pre with trimethylammonium hydroxide (TMAH) increases with increasing the concentration and weight loss. Analysis using scanning electron microscope suggested the uniform reorganization of the macrofibrils of the Lyocell fiber treated with 5.0 mol/l of NaOH solution while the pretreatment in TMAH and LiOH led to the uneven reorganization, resulting in the acceleration of fibrillation. The results indicate that the fibrillation of Lyocell fiber is retarded when the fiber structure is uniformly reorganized without the high loss of cellulose component.
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a kinetic study of moisture sorption and desorption on Lyocell fibers
Carbohydrate Polymers, 2004Co-Authors: Satoko Okubayashi, Ulrich J Griesse, Thomas EchtoldAbstract:Abstract Dynamic water vapor sorption on Lyocell and cotton fibers was gravimetrically investigated at 20 °C. Lyocell fiber showed a higher equilibrium moisture regain of 9.23% w/w at 60% relative humidity compared to 5.54% w/w for the cotton. The hysteresis between the sorption and desorption isotherms for Lyocell was 46.9% and higher than 24.7% for cotton. The hysteresis decreased with increasing relative humidity of the atmosphere. A good fit of the experimental data with the parallel exponential kinetics model suggests that moisture exchange on Lyocell and on cotton is based on two different mechanisms. The kinetic parameters for the identified components of slow and fast sorption were estimated from the simulations and moreover the BET surface volume was calculated. The mechanism of water vapor sorption on cellulosic fibers are discussed considering the effects of the relative humidity on the kinetic parameters, water retention capacity, BET surface volume and the hysteresis effect.
Sung Hoo Jeong - One of the best experts on this subject based on the ideXlab platform.
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an electrocatalytic active Lyocell fabric cathode based on cationically functionalized and charcoal decorated graphite composite for quasi solid state dye sensitized solar cell
Solar Energy, 2017Co-Authors: Naveed Mengal, Iftikhar Ali Sahito, Alvira Ayoub Arbab, Anam Ali Memo, Sung Hoo JeongAbstract:Abstract The state of the art of conductive functional textile woven fabrics have given rise to a demand for textile integrated electrodes. Herein, we report a highly conductive and flexible woven fabric electrode using highly absorbent Lyocell fabric as the substrate and cationically functionalized and activated charcoal decorated graphite composite (AC-GC) as the coating film. This (AC-GC) coated Lyocell fabric is used as a cathode for quasi-solid state dye sensitized solar cell (Q-DSSCs). Our suggested fabric based cathode shows sufficiently high conductivity and electrocatalytic activity (ECA) compared to platinum (Pt) based reference counter electrode (CE). This efficient CE demonstrates extremely low charge transfer resistance (RCT) of 1.56 Ω cm2 with polyethylene oxide based quasi-solid electrolyte. The cationic charged enriched charcoal decorated graphite planner structure provide more availability of active sites for the reduction of negatively charged tri-iodide ( I 3 - ) ions present in polymeric gel electrolyte. The formation of porous charcoal voids and conductive graphite channels entrap large amounts of gel electrolyte and provide fast diffusion of iodide/tri-iodide ( I - / I 3 - ) ions. Our organic system of AC-GC coated Lyocell fabric based DSSCs assembly demonstrated 7.09% power conversion efficiency (PCE) when fabricated with quasi-solid electrolyte. This AC-GC coated fabric CE is also highly stable in water and electrolyte solution. The adequate electrocatalytic activity and cyclic stability demonstrate that this AC-GC coated fabric can be used to replace expensive Pt CE and can be used in flexible solar cells in future.
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citric acid based durable and sustainable flame retardant treatment for Lyocell fabric
Carbohydrate Polymers, 2016Co-Authors: Naveed Mengal, Iftikhar Ali Sahito, Uzma Syed, Samander Ali Malik, Sung Hoo JeongAbstract:Pyrovatex CP New, is a commonly used organophosphorus based flame retardant (FR) reagent for cellulosic materials. However, it has a drawback of high formaldehyde release when used with methylated melamine (MM) based cross-linker, a known carcinogenous compound. In the present approach, a durable and sustainable flame retarding recipe formulation for Lyocell fabrics is developed using citric acid (CA) as a cross-linker. The FR finish was applied by pad-dry-cure process. The treated fabrics were characterized for surface morphology, elemental analysis, TG analysis, char study and FT-IR spectroscopy. Furthermore, flame retardancy, washing durability, formaldehyde release and breaking strength were also assessed, and compared with the conventional MM based FR recipe. The fabric samples treated with 400gL(-1) of FR with either 40 or 80gL(-1) of CA demonstrate flame retardancy even after 10 washing cycles. Furthermore, a 75% reduction in formaldehyde release is achieved. Higher char yield and lower decomposition temperature are found compared to untreated and FR+ MM treated Lyocell. Such an improved sustainable recipe formulation can be used for Lyocell fabric without any health risk in apparel wear.
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fabrication of a flexible and conductive Lyocell fabric decorated with graphene nanosheets as a stable electrode material
Carbohydrate Polymers, 2016Co-Authors: Naveed Mengal, Iftikhar Ali Sahito, Alvira Ayoub Arbab, Muhammad Bilal Qadi, Anam Ali Memo, Sung Hoo JeongAbstract:Abstract Textile electrodes are highly desirable for wearable electronics as they offer light-weight, flexibility, cost effectiveness and ease of fabrication. Here, we propose the use of Lyocell fabric as a flexible textile electrode because of its inherently super hydrophilic characteristics and increased moisture uptake. A highly concentrated colloidal solution of graphene oxide nanosheets (GONs) was coated on to Lyocell fabric and was then reduced in to graphene nanosheets (GNs) using facile chemical reduction method. The proposed textile electrode has a very high surface conductivity with a very low value of surface resistance of only 40 Ω sq −1 , importantly without use of any binding or adhesive material in the processing step. Atomic force spectroscopy (AFM) and Transmission electron microscopy (TEM) were conducted to study the topographical properties and sheet exfoliation of prepared GONs. The surface morphology, structural characterization and thermal stability of the fabricated textile electrode were studied by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), X ray photon spectroscopy (XPS), Raman spectroscopy, Wide angle X ray diffraction spectroscopy (WAXD) and Thermogravimetric analysis (TGA) respectively. These results suggest that the GONs is effectively adhered on to the Lyocell fabric and the conversion of GONs in to GNs by chemical reduction has no adverse effect on the crystalline structure of textile substrate. The prepared graphene coated conductive Lyocell fabric was found stable in water and electrolyte solution and it maintained nearly same surface electrical conductivity at various bending angles. The electrical resistance results suggest that this Lyocell based textile electrode (L-GNs) is a promising candidate for flexible and wearable electronics and energy harvesting devices.
