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Wenwen Fang, Emma Sairanen, Sami Vuori, Marja Rissanen, Isabella Norrbo, ,
ACS Sustainable Chemistry & Engineering; https://doi.org/10.1021/acssuschemeng.1c05938

Abstract:
Textile-based wearable sensors integrated into daily wear offer opportunities for on-demand, real-time self-diagnosis to monitor health conditions with changing environmental surroundings and hazards. One still underrated environmental hazard is accumulated UV irradiation, causing skin burns, accelerated aging, and skin cancers. Here, we have demonstrated a sustainable fiber manufacture process to integrate photochromic hackmanite micro-particles directly into a cellulose body to achieve UV-sensing functionality in daily-life textiles. The hackmanite particles were dispersed into an ionic liquid cellulose dope using ultrasonication and nanofibrillated cellulose as a dispersant, resulting in good spinnability. The obtained fibers possess high mechanical strength with up to 10% photochromic hackmanite loading. To demonstrate its application in wearable UV sensors, the fibers were spun into yarn and then knitted into a piece of jersey fabric. The coloration of hackmanite-incorporated textiles under UV irradiation is readily quantified by image analysis using red–green–blue ratios, which was further utilized for UV dosimetry with a smartphone application showcasing the practical use of the UV sensor. The UV-sensing functionality remained the same after intensive washing and abrasion tests, further demonstrating the feasibility of its application in everyday garments.
Shiori Suzuki, Azusa Togo,
Published: 10 November 2021
The publisher has not yet granted permission to display this abstract.
Published: 12 October 2021
Cellulose, Volume 28, pp 10921-10938; https://doi.org/10.1007/s10570-021-04230-w

Abstract:
Cellulose is an historical polymer, for which its processing possibilities have been limited by the absence of a melting point and insolubility in all non-derivatizing molecular solvents. More recently, ionic liquids (ILs) have been used for cellulose dissolution and regeneration, for example, in the development of textile fiber spinning processes. In some cases, organic electrolyte solutions (OESs), that are binary mixtures of an ionic liquid and a polar aprotic co-solvent, can show even better technical dissolution capacities for cellulose than the pure ILs. Herein we use OESs consisting of two tetraalkylphosphonium acetate ILs and dimethyl sulfoxide or γ-valerolactone, as co-solvents. Cellulose can be first dissolved in these OESs at 120 °C and then regenerated, upon cooling, leading to micro and macro phase-separation. This phenomenon much resembles the upper-critical solution temperature (UCST) type thermodynamic transition. This observed UCST-like behavior of these systems allows for the controlled regeneration of cellulose into colloidal dispersions of spherical microscale particles (spherulites), with highly ordered shape and size. While this phenomenon has been reported for other IL and NMMO-based systems, the mechanisms and phase-behavior have not been well defined. The particles are obtained below the phase-separation temperature as a result of controlled multi-molecular association. The regeneration process is a consequence of multi-parameter interdependence, where the polymer characteristics, OES composition, temperature, cooling rate and time all play their roles. The influence of the experimental conditions, cellulose concentration and the effect of time on regeneration of cellulose in the form of preferential gel or particles is discussed. Regular micro-sized particles regenerated from a cellulose-OES mixture of tetrabutylphosphonium acetate:DMSO (70:30 w/w) upon cooling
, Beatrice Swensson, Diana Bernin, Merima Hasani
Published: 12 October 2021
European Polymer Journal, Volume 161; https://doi.org/10.1016/j.eurpolymj.2021.110822

Abstract:
N,N-dimethylmorpholinium hydroxide was synthesized and its ability to dissolve microcrystalline cellulose and pulp was assessed for the first time. Microscopy and UV-Vis measurements showed that dissolution occurred over a range of 1-2 M concentration of the solvent and a maximum solubility of 7 wt% microcrystalline cellulose could be achieved. The stability of cellulose solutions was evaluated by size exclusion chromatography, which did not detect degradation to any noticeable extent. This observation was further confirmed by 13C NMR measurements. Finally, DLS studies confirmed that most of the cellulose was molecularly dissolved, with intrinsic viscosity values indicating cellulose chains expansion in this solvent.
Published: 7 October 2021
Cellulose, Volume 28, pp 11165-11181; https://doi.org/10.1007/s10570-021-04220-y

Abstract:
The production of cellulose-based textile fibers with high toughness is vital for extending the longevity and thus developing a sustainable textile industry by reducing the global burden of microplastics. This study presented strategies to improve fiber toughness by tuning spinneret geometries. Experimental studies were conducted by spinning with different spinneret geometries and measuring the mechanical and structural properties of the spun fibers. In addition, numerical simulation tools were used to better understand the effects of spinneret geometry. The altering parameters of the spinneret geometries were the capillary diameters D, the angle of the entry cone into the spinning capillary, and the ratio of capillary length to diameter L/D. The highest fiber toughness could be achieved at a capillary aspect ratio of 1 to 2. The obtained maximum fiber toughness was 93 MPa with a tensile strength of 60 cN/tex and a concomitant elongation of 16.5%. For these fiber properties, a 13 wt% solution of a high-purity pulp with higher viscosity in [DBNH][OAc] was spun into a 1.3 dtex fiber using a D100 spinneret with a capillary of 1:1 length/diameter and an entrance angle of 8°. It was noticeable that the microvoid orientations decreased almost linearly with increasing toughness of the fibers. The morphologies of the fibers were similar regardless of the spinneret geometries and the raw materials used in the spinning process. In summary, by modulating the spinneret geometries, Ioncell fibers obtained high toughness that have the potential to replace synthetic fibers.
Mukesh Kumar Singh, Annika Singh
Published: 24 September 2021
Characterization of Polymers and Fibres pp 1-27; https://doi.org/10.1016/b978-0-12-823986-5.00002-6

The publisher has not yet granted permission to display this abstract.
Published: 13 September 2021
by MDPI
Materials, Volume 14; https://doi.org/10.3390/ma14185273

Abstract:
Three alkaline mixtures (NaOH/thiourea, NaOH/urea/thiourea, NaOH/urea/ZnO) and sulfuric acid were used at low temperatures as cellulose solvents, and their cellulose solubility and films’ physical properties for bleached chemical wood pulps and cotton linter were compared. Their degree of polymerization (DP) was controlled to 600–800 before dissolution. Among the alkaline solvents, NaOH/urea/ZnO gave the film the highest tensile strength and stretch. When compared to sulfuric acid, NaOH/urea/ZnO gave lower strength properties but higher crystallinity indices in the films. While alkaline solvents could not dissolve the high DP cellulose (DP ~ 2000), sulfuric acid could dissolve the high DP cellulose at below zero Celsius temperature, and the strength properties of the films were not much different from that of the low DP one. It appeared that the low-temperature sulfuric acid treatment did away with the cellulose’s DP controlling stage; it decreased cellulose DP very quickly for the high-DP cellulose at the initial stage, and as soon as the cellulose DP reached a DP low enough for dissolution, it began to dissolve the cellulose to result in stable cellulose solution.
Kaniz Moriam, Daisuke Sawada, Kaarlo Nieminen, Michael Hummel, Yibo Ma, Marja Rissanen,
Published: 22 August 2021
Cellulose, Volume 28, pp 9547-9566; https://doi.org/10.1007/s10570-021-04134-9

Abstract:
The production of sustainable and high-performance fabrics requires high mechanical strength of the individual (staple) fibers. Although Ioncell fibers already exhibit higher fiber strength than commercial man-made cellulose fibers or cotton fibers, we further aimed to increase both strength and toughness to gradually approach synthetic fibers in these properties. Decisive factors for the achievable mechanical properties of the fibers were the pulp purity, the cellulose concentration in the spinning solution and length-to-diameter (L/D) ratio of the cylindrical part of the spinneret. The absence of low molecular weight fractions in combination with an increased average molecular weight had the highest impact on the achievement of both high strength and toughness. Using a spinneret with a high L/D ratio, it was possible to spin Ioncell fibers with a tensile strength of 925 MPa (61.5 cN/tex) and a modulus of toughness of 83.3 MPa (55.5 J/g). According to a fluid dynamic simulation, uniformly longer molecular cellulose chains in combination with a longer cylindrical capillary promoted an effective alignment of the cellulose molecules inside the spinneret capillary before entering the airgap, thus creating the conditions for a simultaneous increase in tensile strength and elongation i.e. toughness of the fiber. Mechanistically, high fiber toughness is caused by the structural parameters in longitudinal direction, in particular by a higher tilt angle, a longer periodicity of the lamellar plane and lower micro void orientation. In summary, we have developed lyocell-type fibers with high strength and toughness, which can potentially be used as a surrogate for synthetic fibers. Graphic abstract
, Katarzyna Grabowska, Dariusz Wawro, Justyna Wietecha, Zofia Wysokińska
Published: 18 August 2021
Autex Research Journal; https://doi.org/10.2478/aut-2021-0033

Abstract:
The paper aims to present the main tendencies on the global and European natural polymer markets in recent years from the point of view of the requirements and achievements of the European Commission that have been expressed in recent programs and Strategies, with special reference to the Circular Economy New Action Plan and the European Green Deal—the EU Strategies for Climate Neutrality. Natural polymers play an important role among biodegradable products whose role in the production and international trade has been systematically increasing, especially since the middle of the last decade of the new century (2015). Natural polymers are also recommended by the EU from the point of view of their specific importance in the group of biodegradable products.
, Sally A. Ralph, Carlos Baez, Richard S. Reiner
Published: 13 August 2021
Cellulose, Volume 28, pp 9069-9079; https://doi.org/10.1007/s10570-021-04124-x

The publisher has not yet granted permission to display this abstract.
Azusa Togo, Shiori Suzuki, Satoshi Kimura,
Published: 27 July 2021
ACS Omega, Volume 6, pp 20361-20368; https://doi.org/10.1021/acsomega.1c02365

Abstract:
α-1,3-Glucan is a linear and crystalline polysaccharide which is synthesized by in vitro enzymatic polymerization from sucrose. A previous study reported that regenerated fibers of α-1,3-glucan were prepared using a wet-spinning method. However, the mechanical properties were poorer than cellulose regenerated fibers. Then, in this study, the mechanical properties of the regenerated α-1,3-glucan fiber were improved by the transformation of the crystal structure and stretching. The regenerated fiber stretched in water and dehydrated by heating showed high tensile strength (18 cN/tex) that is comparable with that of viscose rayon. Moreover, the crystal structures of the regenerated fibers were investigated using wide-angle X-ray diffraction (WAXD). To date, four crystal polymorphs of α-1,3-glucan from polymorph I to IV have been reported. This study revealed that the regenerated α-1,3-glucan fibers had two different polymorphs, polymorph II (hydrated form) and polymorph III (anhydrous form), depending on post-treatment methods of stretching and annealing procedures. Furthermore, the obtained distinctive 2D-WAXD patterns suggested that polymorph III is identical to polymorph IV.
, S.S. Muthu
Journal of Fashion Marketing and Management; https://doi.org/10.1108/jfmm-12-2020-0260

Abstract:
Purpose In the last two decades, the fashion value chain traveled to developing parts of the world. To these nations, it paved a path for socio-economic development initially but lately, the aftermath has costed more. This article visualizes the gains and losses of fast fashion to these countries. Design/methodology/approach An in-depth systematic literature review was performed to analyze the secondary data from academic journals and reports from international organizations. The authors have compiled their empirical journeys in academia, research and industry from low- and middle-income countries (LMICs) based on Schon's (1983, 1990) theory of reflective practice. Further on, the article is structured using the value chain analysis (VCA) method which visualizes the aftermath of mass-producing fashion for the developed countries. Findings In this research it was found that LMICs have made substantial economic progress in the past two decades, however at a high social and environmental cost. It is the right time to find a balance between economic development and harm caused to the citizens of these nations. Originality/value At the moment the existing academic literature talks about unsustainable practices in the fashion sector around the world. This research precisely targets the LMICs where the aftermath is supposed to be much more severe. Further, it provides solutions and urges these nations to bring a substantial change throughout the value chain for a robust future.
, Mikaela Trogen, Hilda Zahra, Leena Pitkänen, Kaniz Moriam, Marja Rissanen, Mikko Mäkelä, Herbert Sixta, Michael Hummel
Published: 28 May 2021
Abstract:
Cellulose can be dissolved with another biopolymer in a protic ionic liquid and spun into a bicomponent hybrid cellulose fiber using the Ioncell® technology. Inside the hybrid fibers, the biopolymers are mixed at the nanoscale, and the second biopolymer provides the produced hybrid fiber new functional properties that can be fine-tuned by controlling its share in the fiber. In the present work, we present a fast and quantitative thermoanalytical method for the compositional analysis of man-made hybrid cellulose fibers by using thermogravimetric analysis (TGA) in combination with chemometrics. First, we incorporated 0–46 wt.% of lignin or chitosan in the hybrid fibers. Then, we analyzed their thermal decomposition behavior in a TGA device following a simple, one-hour thermal treatment protocol. With an analogy to spectroscopy, we show that the derivative thermogram can be used as a predictor in a multivariate regression model for determining the share of lignin or chitosan in the cellulose hybrid fibers. The method generated cross validation errors in the range 1.5–2.1 wt.% for lignin and chitosan. In addition, we discuss how the multivariate regression outperforms more common modeling methods such as those based on thermogram deconvolution or on linear superposition of reference thermograms. Moreover, we highlight the versatility of this thermoanalytical method—which could be applied to a wide range of composite materials, provided that their components can be thermally resolved—and illustrate it with an additional example on the measurement of polyester content in cellulose and polyester fiber blends. The method could predict the polyester content in the cellulose-polyester fiber blends with a cross validation error of 1.94 wt.% in the range of 0–100 wt.%. Finally, we give a list of recommendations on good experimental and modeling practices for the readers who want to extend the application of this thermoanalytical method to other composite materials.
Prakash Parajuli, Sanjit Acharya, Shaida Sultana Rumi, Tanjim Hossain,
Fundamentals of Natural Fibres and Textiles pp 87-110; https://doi.org/10.1016/b978-0-12-821483-1.00015-2

The publisher has not yet granted permission to display this abstract.
, Mindaugas Bulota, Michael Hummel, Simona Sriubaitė, Mark Hughes, Herbert Sixta, Jouni Paltakari
Journal of Reinforced Plastics and Composites, Volume 40, pp 741-748; https://doi.org/10.1177/07316844211005393

Abstract:
The present study concentrates on a series of experiments and numerical analyses for understanding the effects of fiber volume fraction ( VF) and draw ratio ( DR) on the effective elastic properties of unidirectional composites made from an epoxy resin matrix with a continuous fiber reinforcement. Lyocell-type regenerated cellulose filaments (Ioncell) spun with DRs of 3, 6, and 9 were used. In accordance with the specimens in situ, the fibers were modeled as slender solid elements, for which the ratio between the diameter and length was taken to be much less than unity and deposited inside the matrix with the random sequential adsorption algorithm. The embedded element method was thereafter used in the numerical framework due to its computational advantages and reasonable predictions for continuous fiber reinforced composites. Experiments and numerical investigations were carried out, the results of which were compared, and positive trends for both fiber VFs and DRs on the effective properties were observed. The presented experimental and numerical results and models herein are believed to advance the state of the art in the mechanical characterization of composites with continuous fiber reinforcement.
Jinling Li, Shan Lu, , Qian Qiao, , Jin Zhu
ACS Sustainable Chemistry & Engineering, Volume 9, pp 4744-4754; https://doi.org/10.1021/acssuschemeng.0c08907

The publisher has not yet granted permission to display this abstract.
Azusa Togo, Shiori Suzuki, Satoshi Kimura,
ACS Applied Polymer Materials, Volume 3, pp 2063-2069; https://doi.org/10.1021/acsapm.1c00114

The publisher has not yet granted permission to display this abstract.
Shiori Suzuki, Azusa Togo, Hongyi Gan, Satoshi Kimura,
ACS Sustainable Chemistry & Engineering, Volume 9, pp 4247-4255; https://doi.org/10.1021/acssuschemeng.1c00488

The publisher has not yet granted permission to display this abstract.
, Yoshiharu Nishiyama, Thomas Röder, Lionel Porcar, Hilda Zahra, Mikaela Trogen, Herbert Sixta, Michael Hummel
Published: 11 February 2021
Abstract:
The nanometric internal structure of polymeric fibres is fundamental for their mechanical properties. Two-dimensional small angle neutron scattering patterns were collected to obtain structural parameters of the elementary fibrils in regenerated cellulose fibres prepared by various fibre spinning technologies. Scattering features were fitted to model functions to derive parameters such as elementary fibril radius, long period of the repeating units of crystal and amorphous phase along the fibre axis, degree of orientation, and ellipticity. The correlation between structural parameters and the mechanical properties was studied for the fibres of different existing spinning processes and for the high-strength fibres. Former group showed high correlation with mechanical properties. The latter group showed generally lower correlation, but showed relatively high correlation with the long period. These structural parameters provide a basis for understanding the structure-property relationship of regenerated cellulose fibres as function of spinning types and conditions for further optimization.
Marta Gubitosi, Shirin Asaadi, Herbert Sixta,
Published: 8 February 2021
Abstract:
We present a small angle X-ray scattering (SAXS) study of the colloidal structure of regenerated cellulose fibers, air-gap spun from an ionic liquid solution. Based on the data, and a different interpretation of the anisotropic SAXS pattern, we propose a slightly different colloidal structure of the fibers, than what is commonly assumed for regenerated cellulose fibers. Fibers with two different degrees of orientation, as produced by different draw ratios, DR = 2 and 15, respectively, are analyzed. The 2D SAXS pattern is highly anisotropic with striking cross-like pattern, having scattering predominantly perpendicular and parallel to the fiber axis. This cross-like pattern suggest a colloidal structure with oriented crystalline lamellae of ca. 10 nm thickness, embedded within a continuous matrix of amorphous cellulose. The lamellae are oriented with their normal parallel with the fiber axis. Complementary wide angle X-ray diffraction data confirm that the lamellae normal direction corresponds to the cellulose chain direction (c-direction) in the monoclinic cellulose crystal (Cellulose II). Graphic abstract
Marc P. Vocht, Ronald Beyer, Patricija Thomasic, Alexandra Müller, Antje Ota, ,
Published: 1 February 2021
Cellulose, Volume 28, pp 3055-3067; https://doi.org/10.1007/s10570-021-03697-x

Abstract:
We report on a new process for the spinning of high-performance cellulosic fibers. For the first time, cellulose has been dissolved in the ionic liquid (IL) 1-ethyl-3-methylimidazolium octanoate ([C2C1im][Oc]) via a thin film evaporator in a continuous process. Compared to other ILs, [C2C1im][Oc] shows no signs of hydrolysis with water. For dope preparation the degree of polymerization of the pulp was adjusted by electron beam irradiation and determined by viscosimetry. In addition, the quality of the pulp was evaluated by means of alkali resistance. Endless filament fibers have been spun using dry-jet wet spinning and an extruder instead of a spinning pump, which significantly increases productivity. By this approach, more than 1000 m of continuous multifilament fibers have been spun. The novel approach allows for preparing cellulose fibers with high Young's modulus (33 GPa) and unprecedented high tensile strengths up to 45 cN/tex. The high performance of the obtained fibers provides a promising outlook for their application as replacement material for rayon-based tire cord fibers.
Sozan Darabi, , Sami Rantasalo, Marja Rissanen, Ingrid Öberg Månsson, Haike Hilke, , , , , et al.
ACS Applied Materials & Interfaces, Volume 12, pp 56403-56412; https://doi.org/10.1021/acsami.0c15399

Abstract:
The emergence of “green” electronics is a response to the pressing global situation where conventional electronics contribute to resource depletion and a global build-up of waste. For wearable applications, green electronic textile (e-textile) materials present an opportunity to unobtrusively incorporate sensing, energy harvesting, and other functionality into the clothes we wear. Here, we demonstrate electrically conducting wood-based yarns produced by a roll-to-roll coating process with an ink based on the biocompatible polymer:polyelectrolyte complex poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). The developed e-textile yarns display a, for cellulose yarns, record-high bulk conductivity of 36 Scm–1, which could be further increased to 181 Scm–1 by adding silver nanowires. The PEDOT:PSS-coated yarn could be machine washed at least five times without loss in conductivity. We demonstrate the electrochemical functionality of the yarn through incorporation into organic electrochemical transistors (OECTs). Moreover, by using a household sewing machine, we have manufactured an out-of-plane thermoelectric textile device, which can produce 0.2 μW at a temperature gradient of 37 K.
, Simona Sriubaite, Anne Michud, Kaarlo Nieminen, Mark Hughes, Herbert Sixta,
Published: 24 November 2020
Journal of Applied Polymer Science, Volume 138; https://doi.org/10.1002/app.50306

The publisher has not yet granted permission to display this abstract.
, Ilkka A. Kilpeläinen
Published: 19 November 2020
RSC Advances, Volume 10, pp 42200-42203; https://doi.org/10.1039/d0ra08892g

Abstract:
Thermochemical analysis of cellulose dissolution character in the superbase containing protic ionic liquid [m-TBDH][AcO] reveals lower critical solution temperature (LCST) behaviour.
Leo Svenningsson, , Kerstin Jedvert, , ,
Published: 8 November 2020
Carbohydrate Polymers, Volume 254; https://doi.org/10.1016/j.carbpol.2020.117293

Abstract:
Cellulose-lignin composite carbon fibers have shown to be a potential environmentally benign alternative to the traditional polyacrylonitrile precursor. With the associated cost reduction, cellulose-lignin carbon fibers are an attractive light-weight material for e.g. wind power and automobile manufacturing. The carbon fiber tenacity, tensile modulus and creep resistance is in part determined by the carbon content and the molecular orientation distribution of the precursor. This work disassociates the molecular orientation of different components in cellulose-lignin composite fibers using rotor-synchronized solid-state nuclear magnetic resonance spectroscopy and X-ray scattering. Our results show that lignin is completely disordered, in a mechanically stretched cellulose-lignin composite fiber, while the cellulose is ordered. In contrast, the native spruce wood raw material displays both oriented lignin and cellulose. The current processes for fabricating a cellulose-lignin composite fiber can not regain the oriented lignin as observed from the native wood.
, Marja Rissanen, Xiang You, Kaniz Moriam, Michael Hummel,
Published: 24 October 2020
Cellulose, Volume 28, pp 31-44; https://doi.org/10.1007/s10570-020-03513-y

Abstract:
In this study, we propose a convenient method for testing the fibrillation tendency of man-made cellulosic fibres (MMCFs) and investigate the possibility to apply a commercial crosslinker for Tencel fibres on the ionic liquid-based regenerated cellulosic fibre (Ioncell fibre). The fibrillation tendency of various MMCFs including viscose, Modal, Tencel and Ioncell fibres were examined through wet abrasion by using ball bearing and blending methods. The fibrillation tests using a laboratory blender was found to be a superior method over the ball bearing method in terms of time and energy saving. The fibrillation tendency of the fibres highly depended on their cellulose molecular orientation and the treatment intensity (time, temperature and alkalinity) in the blender. This fibrillation method was also applied to discover the effect of the crosslinking on the fibrillation tendency of the fibres. The Ioncell fibre proved to be suitable for crosslinking treatment to reduce fibrillation using 1,3,5-triacryloyl-hexahydro-1,3,5-triazine (TAHT)—a commercial Tencel crosslinker.
International Journal of Biological Macromolecules, Volume 165, pp 2520-2527; https://doi.org/10.1016/j.ijbiomac.2020.10.145

Abstract:
Tuning the composition of regenerated lignocellulosic fibers in the production process enables targeting of specific material properties. In composite materials, such properties could be manipulated by controlled heterogeneous distribution of chemical components of regenerated fibers. This attribute requires a visualization method to show their inherent chemical characteristics. We compared complementary microscopic techniques to analyze the surface chemistry of four differently tuned regenerated lignocellulosic fibers. Adhesion properties were visualized with chemical force microscopy and showed contrasts towards hydrophilic and hydrophobic atomic force microscopy tips. Fibers containing xylan showed heterogeneous adhesion properties within the fiber structure towards hydrophilic tips. Additionally, peak force infrared microscopy mapped spectroscopic contrasts with nanometer resolution and provided point infrared spectra, which were consistent to classical infrared microscopy data. With this setup, infrared signals with a spatial resolution below 20 nm reveal chemical gradients in specific fiber types.
Published: 20 October 2020
Cellulose, Volume 28, pp 533-547; https://doi.org/10.1007/s10570-020-03505-y

Abstract:
Lyocell fibers have received increased attention during the recent years. This is due to their high potential to satisfy the rising market demand for cellulose-based textiles in a sustainable way. Typically, this technology adopts a dry-jet wet spinning process, which offers regenerated cellulose fibers of excellent mechanical properties. Compared to the widely exploited viscose process, the lyocell technology fosters an eco-friendly process employing green direct solvents that can be fully recovered with low environmental impact. N-methylmorpholine N-oxide (NMMO) is a widely known direct solvent that has proven its success in commercializing the lyocell process. Its regenerated cellulose fibers exhibit higher tenacities and chain orientation compared to viscose fibers. Recently, protic superbase-based ionic liquids (ILs) have also been found to be suitable solvents for lyocell-type fiber spinning. Similar to NMMO, fibers of high mechanical properties can be spun from the cellulose-IL solutions at lower spinning temperatures. In this article, we study the different aspects of producing regenerated cellulose fibers using NMMO and relevant superbase-based ILs. The selected ILs are 1,5-diazabicyclo[4.3.0]non-5-ene-1-ium acetate ([DBNH]OAc), 7-methyl-1,5,7-triazabicyclo[4.4.0] dec-5-enium acetate ([mTBDH]OAc) and 1,8-diazabicyclo[5.4.0]undec-7-enium acetate ([DBUH]OAc). All ILs were used to dissolve a 13 wt% (PHK) cellulose pulp. The study covers the fiber spinning process, including the rheological characterization of the various cellulose solutions. Moreover, we discuss the properties of the produced fibers such as mechanical performance, macromolecular properties and morphology. Graphic abstract
, Friederike Sommerhoff, Benoit Duchemin, Owen Curnow, Mark P. Staiger
Composites Part A: Applied Science and Manufacturing, Volume 140; https://doi.org/10.1016/j.compositesa.2020.106148

The publisher has not yet granted permission to display this abstract.
, Momoyo Utsumi
Published: 29 September 2020
Cellulose, Volume 27, pp 10441-10446; https://doi.org/10.1007/s10570-020-03462-6

The publisher has not yet granted permission to display this abstract.
Mikaela Trogen, Nguyen-Duc Le, , , , , Herbert Sixta, Riddhi Shah, , Mikhail Balakshin, et al.
Published: 28 September 2020
Carbohydrate Polymers, Volume 252; https://doi.org/10.1016/j.carbpol.2020.117133

The publisher has not yet granted permission to display this abstract.
Laura Berga, Isobel Bruce, Thomas W. J. Nicol, Ashley J. Holding, , , Adam J. Walker,
Published: 12 September 2020
Cellulose, Volume 27, pp 9593-9603; https://doi.org/10.1007/s10570-020-03444-8

Abstract:
The solubility of cellulose has been studied as a function of composition in the binary mixture of 1,1,3,3-tetramethylguanidine and propionic acid. In amine-rich compositions, greater quantities of cellulose can be dissolved than in the equimolar composition, a.k.a. the protic ionic liquid [TMGH][OPr]. By applying a methodology of a short period of heating followed by cooling, similar concentrations of cellulose can be achieved in a much shorter time period. Finally, regeneration of cellulose from solution can be achieved by altering the acid:amine molar ratio. In comparison to cellulose regenerated from these solutions using water as an antisolvent, cellulose regenerated with propionic acid exhibit a lower crystallinity as inferred from x-ray diffractometry, but a greater average molecular weight as inferred from gel permeation chromatography.
, Lijie Huang, Mingzi Xu, Minghui Qi, , Qi Mo, Hanyu Zhao, Chongxing Huang, Shuangfei Wang, Yang Liu
Published: 8 September 2020
ACS Omega, Volume 5, pp 23743-23754; https://doi.org/10.1021/acsomega.0c02713

The publisher has not yet granted permission to display this abstract.
Hilda Zahra, Daisuke Sawada, , Yibo Ma, , Toshiaki Yoshioka, ,
Published: 1 September 2020
Biomacromolecules, Volume 21, pp 4326-4335; https://doi.org/10.1021/acs.biomac.0c01117

Abstract:
Low carbon yield is a major limitation for the use of cellulose-based filaments as carbon fiber precursors. The present study aims to investigate the use of an abundant biopolymer chitosan as a natural charring agent particularly on enhancing the carbon yield of the cellulose-derived carbon fiber. The ionic liquid 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH]OAc) was used for direct dissolution of cellulose and chitosan, and to spin cellulose-chitosan composite fibers through a dry-jet wet spinning process (Ioncell). The homogenous distribution and tight packing of cellulose and chitosan revealed by X-ray scattering experiments, enables synergistic interaction between the two polymers during the pyrolysis reaction, resulting in a substantial increase of carbon yield and preservation of mechanical properties of cellulose fiber compared to other co-biopolymers such as lignin and xylan.
Sherif Elsayed, Sanna Hellsten, Chamseddine Guizani, Joanna Witos, Marja Rissanen, Antti H Rantamäki, Pauliina Varis, , Herbert Sixta
ACS Sustainable Chemistry & Engineering, Volume 8; https://doi.org/10.1021/acssuschemeng.0c05330

The publisher has not yet granted permission to display this abstract.
, Sauli Larkiala, Kaniz Moriam, Daisuke Sawada, Sherif Elsayed, Sami Rantasalo, Michael Hummel, Herbert Sixta
Journal of Applied Polymer Science, Volume 138; https://doi.org/10.1002/app.49787

Abstract:
A novel, small‐volume vertically arranged spin bath was successfully developed for an air gap lyocell‐type spinning process. A maximum regeneration bath length with a minimum free volume characterizes the concept of the new spin bath. Using the ionic liquid (IL) 1,5‐diazabicyclo[4.3.0]non‐5‐enium acetate [DBNH][OAc], the spin bath showed very good spinning performances of IL‐cellulose dopes at high draw ratios and spinning duration for single filament spinning experiments. Using this new device, it was possible to get a step further in the optimization of the Ioncell® process and simulate a process closed loop operation by performing single filament spinning in IL/H2O mixtures. Good dope spinnability and preserved fibers mechanical properties were achieved in a coagulation bath containing up to 30 wt% IL. It is only at 45 wt% of IL in the bath that the spinnability and fibers mechanical properties started to deteriorate. The fibers fibrillar structure was less pronounced in IL‐containing spinning bath in comparison to a pure water bath. However, their crystallinity after washing was preserved regardless of the spinning bath composition. The results presented in this work have a high relevance to the upscaling of emerging IL‐based cellulose dissolution and spinning processes.
, Daisuke Sawada, Michael Hummel, Herbert Sixta,
Published: 7 July 2020
Cellulose, Volume 27, pp 7399-7415; https://doi.org/10.1007/s10570-020-03312-5

The publisher has not yet granted permission to display this abstract.
Published: 7 April 2020
by 10.1038
Nature Reviews Earth & Environment, Volume 1, pp 189-200; https://doi.org/10.1038/s43017-020-0039-9

The publisher has not yet granted permission to display this abstract.
Yibo Ma, Bijan Nasri-Nasrabadi, Xiang You, Xungai Wang, Thomas J. Rainey,
Published: 21 February 2020
Journal of Natural Fibers, Volume 18, pp 2338-2350; https://doi.org/10.1080/15440478.2020.1726244

Abstract:
Regenerated cellulosic fibers were successfully spun from various waste cellulose sources (cotton linter, bagasse, and cardboard) suitable for use as a textile fibers using a wet spinning process with an ionic liquid/dimethyl sulfoxide (IL/DMSO) mixture as the solvent. The solubility of the waste cellulose sources in IL/DMSO varies according to the source of the raw material. Regenerated fibers can be spun from all the waste feedstock, the spinnability and fiber tensile strength is governed by the DP and chemical composition of the cellulose. The structural properties of the spun fibers are determined by x-ray diffraction, thermalgravimetric analysis, and scanning electron microscope. The results reveal that the properties of the starting materials and thus how the waste feed streams are pretreated have a significant impact on the mechanical properties, crystallite structure, thermal stability, and the morphology of the fibers.
, Chandra Apriana Purwita
Published: 31 December 2019
JURNAL SELULOSA, Volume 9, pp 51-64; https://doi.org/10.25269/jsel.v9i02.273

Abstract:
Serat sintetis dari minyak bumi memiliki posisi penting dalam produk tekstil. Lebih dari 50% produksi serat dunia didominasi oleh serat sintetik. Meskipun serat sintetik lebih murah, produktivitasnya tinggi, dan lebih tahan lama tetapi serat tersebut tidak dapat terurai secara alami dan proses pembuatannya menggunakan bahan yang dapat merusak lingkungan dan mengancam kesehatan. Meningkatnya kesadaran terhadap isu-isu terkait ekologi dan lingkungan telah mendorong pencarian solusi alternatif bahan baku dan pengembangan metode pembuatan serat yang ramah lingkungan. Serat regenerasi merupakan jenis serat semisintetik yang dibuat dari hasil regenerasi selulosa yang menggunakan bahan baku terbarukan yaitu kayu dan nonkayu yang diproses lebih lanjut menjadi dissolving pulp. Serat ini lebih ramah lingkungan karena lebih mudah terdegradasi. Metode regenerasi serat selulosa lebih berkelanjutan dibandingkan penggunaan bahan baku minyak bumi yang ketersediannya terbatas. Dalam makalah ini dipaparkan sejumlah metode pembuatan serat rayon untuk tekstil menggunakan proses konvensional hingga proses alternatif yang lebih ramah lingkungan. Proses tersebut antara lain proses nitrat, cuproammonium, asetat, viskosa, lyocell, larutan ionik, modal, dan karbamat. Tujuan makalah ini adalah untuk memberikan informasi komprehensif mengenai berbagai proses pembuatan serat rayon serta keunggulan dan kelemahan yang menyertainya, karakteristik dan sifat serat yang diperoleh, dan metode terbaru seperti lyocell dan larutan ionik memiliki dampak lingkungan yang relatif rendah sehingga memiliki potensi untuk dikembangkan. Review: Making Rayon FiberAbstractSynthetic fibers from petroleum have an important position in textile products. More than 50% of the world’s fiber production is dominated by synthetic fibers. Although synthetic fibers are cheaper, high productivity, and more durable, they cannot biodegrade naturally and the manufacturing process uses materials that can damage the environment and threaten health. Increased awareness of issues related to ecology and the environment hasled to the search for alternative solutions for new raw materials and the development of environmentally friendly fiber making process. Regenerated fiber is a type of semisynthetic fiber made from cellulose regeneration using renewable raw materials such as wood and non-wood which are further processed into dissolving pulp. This fiber is more environmentally friendly because it is more easily degraded. Regenerated fiber methods are more sustainable than the use of petroleum raw materials which have limited availability. In this paper, a number of methods for making rayon fibers for textiles are presented using conventional processes to alternative processes that are more environmentally friendly. These processes include nitrate, cuproammonium, acetate, viscose, lyocell, ionic solution, modal, and carbamate. The purpose of this paper is to provide comprehensive information on the various processes of making rayon fibers as well as the advantages and disadvantages, the characteristics and properties of the fibers, and the latest methods such as lyocells and ionic solutions have relatively low environmental impact so that they have the potential to be developed.Keywords: dissolving pulp, rayon fiber, cellulose, textile, viscose
Published: 17 December 2019
Frontiers in Chemistry, Volume 7; https://doi.org/10.3389/fchem.2019.00871

Abstract:
Wood hemicelluloses have an excellent capacity to form and stabilize oil-in-water emulsions. Galactoglucomannans (GGM) from spruce and glucuronoxylans (GX) from birch provide multifunctional protection against physical breakdown and lipid oxidation in emulsions. Phenolic residues, coextracted with hemicelluloses using the pressurized hot water (PHWE) process, seem to further enhance emulsion stability. According to hypothesis, phenolic residues associated with hemicelluloses deliver and anchor hemicelluloses at the emulsion interface. This study is the first to characterize the structure of the phenolic residues in both GGM- and GX-rich wood extracts and their role in the stabilization of emulsions. PHWE GGM and GX were fractionated by centrifugation to obtain concentrated phenolic residues as one fraction (GGM-phe and GX-phe) and partially purified hemicelluloses as the other fraction (GGM-pur and GX-pur). To evaluate the role of each fraction in terms of physical and oxidative stabilization, rapeseed oil-in-water emulsions were prepared using GGM, GX, GGM-pur, and GX-pur as stabilizers. Changes in droplet-size distribution and peroxide values were measured during a 3-month accelerated storage test. The results for fresh emulsions indicated that the phenolic-rich fractions in hemicelluloses take part in the formation of emulsions. Furthermore, results from the accelerated storage test indicated that phenolic structures improve the long-term physical stability of emulsions. According to measured peroxide values, all hemicelluloses examined inhibited lipid oxidation in emulsions, GX being the most effective. This indicates that phenolic residues associated with hemicelluloses act as antioxidants in emulsions. According to chemical characterization using complementary methods, the phenolic fractions, GGM-phe and GX-phe, were composed mainly of lignin. Furthermore, the total carbohydrate content of the phenolic fractions was clearly lower compared to the starting hemicelluloses GGM and GX, and the purified fractions GGM-pur and GX-pur. Apparently, the phenolic structures were enriched in the GGM-phe and GX-phe fractions, which was confirmed by NMR spectroscopy as well as by other characterization methods. The frequency of the main bonding pattern in lignins, the β-O-4 structure, was clearly very high, suggesting that extracted lignin remains in native form. Furthermore, the lignin carbohydrate complex of γ-ester type was found, which could explain the excellent stabilizing properties of PHWE hemicelluloses in emulsions.
Akari Okugawa, Manami Sakaino, Yoshiaki Yuguchi,
Published: 23 November 2019
Carbohydrate Polymers, Volume 231; https://doi.org/10.1016/j.carbpol.2019.115663

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