Anne Michud

Ioncell-F: ionic liquid-based cellulosic textile fibers as an alternative to viscose and Lyocell:

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 this particular ionic liquid for the production of man-made cellulosic fibers and thus give a promising outlook for the future of the Ioncell-F process.

High‐Strength Composite Fibers from Cellulose–Lignin Blends Regenerated from Ionic Liquid Solution

Composite fibres that contain cellulose and lignin were produced from ionic liquid solutions by dry-jet wet spinning. Eucalyptus dissolving pulp and organosolv/kraft lignin blends in different ratios were dissolved in the ionic liquid 1,5-diazabicyclo[4.3.0]non-5-enium acetate to prepare a spinning dope from which composite fibres were spun successfully. The composite fibres had a high strength with slightly decreasing values for fibres with an increasing share of lignin, which is because of the reduction in crystallinity. The total orientation of composite fibres and SEM images show morphological changes caused by the presence of lignin. The hydrophobic contribution of lignin reduced the vapour adsorption in the fibre. Thermogravimetric analysis curves of the composite fibres reveal the positive effect of the lignin on the carbonisation yield. Finally, the composite fibre was found to be a potential raw material for textile manufacturing and as a precursor for carbon fibre production.

Monitoring of cellulose depolymerization in 1-ethyl-3-methylimidazolium acetate by shear and elongational rheology

The thermal stability of cellulose in the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate, [emim]OAc was investigated. For this purpose, Eucalyptus urugrandis prehydrolysis kraft pulp was first dissolved in [emim]OAc by means of a vertical kneader and then stored at three different temperatures to study the time-depended behavior of the cellulose-[emim]OAc system. Cellulose depolymerization was assessed by characterizing the precipitated cellulose and the rheological behavior of the cellulose-[emim]OAc solutions. The results show decreases in the weight average molecular mass and in the shear viscosity at temperatures exceeding 60 °C, which can be related to progressing degradation of cellulose in the IL upon storage at elevated temperature. The changes in behavior of the solutions under extensional stresses also attest the gradual depolymerization of cellulose. The degradation has been analyzed using appropriate kinetic models. Propyl gallate appeared to be an efficient stabilizer of the cellulose-[emim]OAc system during the dissolution step even though the mechanism has not been fully understood yet.

Ionic Liquids for the Production of Man-Made Cellulosic Fibers: Opportunities and Challenges

The constant worldwide increase in consumption of goods will also affect the textile market. The demand for cellulosic textile fibers is predicted to increase at such a rate that by 2030 there will be a considerable shortage, estimated at ~15 million tons annually. Currently, man-made cellulosic fibers are produced commercially via the viscose and Lyocell™ processes. Ionic liquids (ILs) have been proposed as alternative solvents to circumvent certain problems associated with these existing processes. We first provide a comprehensive review of the progress in fiber spinning based on ILs over the last decade. A summary of the reports on the preparation of pure cellulosic and composite fibers is complemented by an overview of the rheological characteristics and thermal degradation of cellulose–IL solutions. In the second part, we present a non-imidazolium-based ionic liquid, 1,5-diazabicyclo[4.3.0]non-5-enium acetate, as an excellent solvent for cellulose fiber spinning. The use of moderate process temperatures in this process avoids the otherwise extensive cellulose degradation. The structural and morphological properties of the spun fibers are described, as determined by WAXS, birefringence, and SEM measurements. Mechanical properties are also reported. Further, the suitability of the spun fibers to produce yarns for various textile applications is discussed.

Renewable High‐Performance Fibers from the Chemical Recycling of Cotton Waste Utilizing an Ionic Liquid

A new chemical recycling method for waste cotton is presented that allows the production of virgin textile fibers of substantially higher quality than that from the mechanical recycling methods that are used currently. Cotton postconsumer textile wastes were solubilized fully in the cellulose-dissolving ionic liquid 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH]OAc) to be processed into continuous filaments. As a result of the heterogeneous raw material that had a different molar mass distribution and degree of polymerization, pretreatment to adjust the cellulose degree of polymerization by acid hydrolysis, enzyme hydrolysis, or blending the waste cotton with birch prehydrolyzed kraft pulp was necessary to ensure spinnability. The physical properties of the spun fibers and the effect of the processing parameters on the ultrastructural changes of the fibers were measured. Fibers with a tenacity (tensile strength) of up to 58 cN tex-1 (870 MPa) were prepared, which exceeds that of native cotton and commercial man-made cellulosic fibers.

The effect of hydration on the micromechanics of regenerated cellulose fibres from ionic liquid solutions of varying draw ratios

Regenerated cellulose fibres - Ioncell-F, have been prepared with different draw ratios from cellulose solution in 1,5-diazabicyclo[4.3.0]non-5-ene-1-ium acetate ([DBNH]OAc) ionic liquid. Properties of the fibres were investigated in dry and wet conditions. The stiffness of fibres decreased on average 5 times upon the hydration while the tensile strength remained at around 70% of the initial value. The effect of hydration on the deformation mechanisms and mechanical properties was addressed using Raman spectroscopy. Bands located at 1095cm(-1) and 1414cm(-1) corresponding to the glucosidic linkage C-O-C and side groups C-O-H were followed upon straining. Raman band shifts were observed indicating molecular deformations. Moreover, the hydration of fibres altered the shifting rates implying changes in the molecular micromechanics. It is suggested that hydration affects inter-chain hydrogen bonds thus resulting in the slippage of the chains and lower stiffness of fibres. Some discrepancies from the series aggregate model have been observed which is indicative of changes in the deformation mechanisms upon hydration of the fibres.

Impact of Water in the Casting of Cellulosic Film from Ionic Liquid Solutions

This study addresses in detail the role of water in the consecutive steps of film forming: cel lulose dissolution, regeneration and drying, and its impact on the mechanical properties of the cellulose film. Prehydrolysis kraft (PHK) pulp was subjected to hydrothermal treatment (HT) prior to its dissolution in 1-ethyl-3-methylimidazolium acetate [emim]OAc. After the treatment, the DP of the pulp was 440 and the polydispersity index was as low as 3.1. HTpretreated pulp was dissolved in [emim]OAc with a water content of 2, 7, 14 and 21 wt%. The pulp dissolution was completed within 15 min regardless of the water content in the solvent. The rheological behavior, one of the key properties in film formation, was deter mined at varied temperature and cellulose concentration. Cellulose films were prepared from solutions with cellulose concentrations of 8, 12 and 16 wt% at a temperature of 90 °C. The impact of water on the macromolecular, morphological and mechanical properties of the transparent films prepared was thoroughly studied. With a very low polydispersity of the cellulose chain, the films prepared revealed high strength ranging from 87 to 106.5 MPa at elongation from 10 to 50% in conditioned state.

Erratum to: Dry jet-wet spinning of strong cellulose filaments from ionic liquid solution

All material supplied via Aaltodoc is protected by copyright and other intellectual property rights, and duplication or sale of all or part of any of the repository collections is not permitted, except that material may be duplicated by you for your research use or educational purposes in electronic or print form. You must obtain permission for any other use. Electronic or print copies may not be offered, whether for sale or otherwise to anyone who is not an authorised user.