Lyocell Research Articles

Efficient anti-fibrillation of lyocell fabric by low-formaldehyde resin

Lyocell fiber is a green kind of renewable cellulose fiber derived from plants and has many excellent properties. However, in the process of production and application of lyocell fiber, due to swelling and external force, it is easy to produce a serious fibrillation phenomenon. The phenomenon of fibrillation has a very serious impact on the quality and application of lyocell products. To solve this problem, a simple and efficient anti-fibrillation treatment technique was explored in this work. The treatment of lyocell fabric with etherification modified dimethylol dihydroxy-ethylene-urea (ultra-low formaldehyde 2D resin) can enhance the lateral interaction force between the macromolecular chains of lyocell fiber and enhance the anti-fibrillation performance of lyocell fiber. The reaction mechanism between ultra-low formaldehyde 2D resin and lyocell cellulose chain was determined by measuring the fabric mechanical properties, fiber swelling degree, chemical element content, and Fourier transform infrared spectroscopy (FTIR). When the finishing solution contained 100 g/L resin and 20 g/L catalyst with pH 3, after the fabric was cured under 160 ℃ for 60 s, the fibrillation phenomenon of the fiber was greatly reduced. After the treatment of the fabric, its mechanical properties were basically not affected. There was a slight decrease in strength, and the hydrophilic properties were not affected obviously. Compared with the traditional rolling-drying-baking process, this method not only has a shorter and simpler process flow but also has less influence on fabric properties, which guaranteed the smooth progress of the subsequent production and application.

PREPARATION OF CITRONELLAL NANOCAPSULES AND STUDY OF ANTIBACTERIAL AND MOSQUITO REPELLENT PROPERTIES OF CITRONELLAL FUCTIONALIZED LYOCELL FIBER

The encapsulation of botanical compounds (such as citronellal) can be used to increase their efficiency and stability for functionalizing textile materials. In this study, the citronellal nanocapsules (CNC) with citronella oil as the core material and isophorone diisocyanate (IPDI) as the shell material were prepared and characterized. Factors, including core-to-shell ratio, single-phase ratios, emulsification time, as well as polymerization time and temperature, were investigated to determine the optimal process for the preparation of CNC. The average particle size of the prepared CNC was about several hundred nanometers, with uniform particle size distribution. Further, composite Lyocell fibers were prepared by the wet spinning process of co-blending CNC with Lyocell spinning stock. Evaluations were made of the biological activity of CNC towards mosquitoes, as well as E. coli and S. aureus, showing excellent mosquito repelling rate, of more than 90%, and an inhibition rate of 97.72% towards S. aureus.

Facile fabrication of adenosine triphosphate/chitosan/polyethyleneimine coating for high flame-retardant lyocell fabrics with outstanding antibacteria

Addressing highly flammable and easily breeding bacteria property via environmentally friendly approach was critical for the large-scale application of lyocell fibers. Herein, a bio-based coating constructed by layer-by-layer deposition of adenosine triphosphate (ATP), chitosan (CS), and polyethyleneimine (PEI) was successfully fabricated to obtain excellent fire-resistant and antimicrobial lyocell fabrics (LBL/Lyocell). The resulted fabrics with add-on of 11.5 wt% achieved the limiting oxygen index (LOI) of 32.0 %. Meanwhile, compared with the pure lyocell fabrics, the peak of heat release rate (PHRR), total heat release (THR), and fire growth rate (FIGRA) of LBL/Lyocell fabrics decreased by 75.2 %, 61.0 % and 69.8 % in cone calorimetric test (CCT), respectively. By characterizing the gaseous products and solid residues, the presence of the ATP/CS/PEI coating could not only quickly form the dense expanded carbon layer by itself, but also promote the conversion of cellulose into thermal-stability residues, thus reducing the release of combustible substances during combustion and protecting the lyocell fabrics. In addition, LBL/Lyocell showed excellent antimicrobial properties with 99.99 % antibacterial rates against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). This bio-based coating was a promising candidate for efficiently flame-retardant cellulose fibers with excellent antibacteria.

N‐methylmorpholine‐N‐oxide molecules coated ammonium polyphosphates for dope spinning of flame‐retardant lyocell fiber

AbstractLyocell fiber, hailed as the “verdant filament of the 21st century,” boasts elevated tensile strength, environmentally conscientious production practices, and innate biodegradability. Nonetheless, its intrinsic combustibility constitutes a noteworthy impediment to its pervasive utilization across textile and industrial domains. In a concerted effort to surmount this challenge, ammonium polyphosphate (APP) underwent modification through the infusion of N‐methylmorpholine‐N‐oxide (NMMO) molecules, amplifying its dispersibility within lyocell solutions. The resultant NMMO‐coated ammonium polyphosphate (NAPP) underwent meticulous characterization of both its structure and properties. Remarkably, lyocell fiber impregnated with 30% NAPP exhibited exemplary flame retardancy, enduring through 30 laundering cycles. Notably, its tensile strength remained notably robust at 139 MPa, demonstrating a mere 6.1% reduction in comparison to its pristine lyocell counterpart. This study delineates a promising trajectory for the fabrication of mechanically resilient lyocell fibers endowed with commendable flame‐retardant attributes.Highlights The raw material is waste cotton textiles, prepared on a green basis. The use of ultrasonic mixing and low‐speed stirring defoaming method and the use of room temperature spinning advantage of the production of flame retardant lyocell fiber. The amount of flame retardant is small, and the mechanical strength is reduced to a lesser extent. Good flame‐retardant effect and excellent water washing resistance.

Preparation and performance of stainless steel fiber/Lyocell fiber-blended weft-knitted fabric

Abstract Stainless steel fiber exhibits excellent flame retardancy and melting resistance, but it lacks thermal and moisture comfort. To compensate for these shortcomings, stainless steel fiber was blended with Lyocell fiber in ratios of 0/100, 10/90, 20/80, and 30/70%. The blended yarn was then formed into a single-sided plain stitch fabric of stainless steel fiber and finished with a phosphorus–nitrogen flame retardant. Next, the effects of the blending ratio on the fundamental properties, thermal and moisture comfort, and flame retardancy of the blended yarn and its fabric were studied. Considering these parameters alongside cost, the 10% stainless steel fiber-blended fabric was the optimal choice and showed potential applications for updating and upgrading welding service fabrics.

Bioinspired phosphorus-free and halogen-free biomass coatings for durable flame retardant modification of regenerated cellulose fibers

Inspired by mussel adhesion and intrinsic flame retardant alginate fibers, a biomass flame retardant (PPCA) containing adhesive catechol and sodium carboxylate structure (-COO−Na+) based on biomass amino acids and protocatechualdehyde was designed to prepare flame retardant Lyocell fibers (Lyocell@PPCA@Na). Furthermore, through the substitution and chelation of metal ions by PPCA in the cellulose molecular chain, flame retardant Lyocell fibers chelating copper and iron ions (Lyocell@PPCA@Cu, Lyocell@PPCA@Fe) were prepared. Compared with the original sample, the peak heat release rate (PHRR) and total heat release (THR) for modified Lyocell fibers were significantly reduced. In addition, the modified sample exhibited a certain flame retardant durability. TG-FTIR analysis showed that the release of flammable gaseous substances was inhibited. The introduction of Schiff bases and aromatic structures in PPCA, as well as the decomposition of carboxylic metal salts were beneficial for the formation of char residue containing metal carbonates and metal oxides to play the condensed phase flame retardant effect. This work develops a new idea for the preparation of eco-friendly flame retardant Lyocell fibers without the traditional flame retardant elements such as P, Cl, and Br.

Synergetic construction of color and multifunction for sustainable lyocell fabric by microbial nano pigment

As a kind of low-carbon, environmentally friendly and high-quality regenerated cellulose fiber derived from nature plant, the promotion and application of lyocell fiber is attracting much attention. In this paper, for the first time, microbial pigment was applied for color and multifunction construction of lyocell fabric. The size change of the pigment nano-particles during the color construction process was explored to verify the dyeing mechanism of nano-suspension system, and the optimal dyeing condition was obtained. In order to improve the dyeing effect and functionality of fabric, 1,2,3,4-butanetetracarboxylic acid (BTCA) was used to realize the anionic modification of lyocell fabric with high strength retention rate. Under optimal color construction condition, the color depth of the modified fabric was 298.5% higher than that of the unmodified one, and the dyed fabric possessed excellent dyeing uniformity and permeability. Moreover, the crosslinking reaction between BTCA and cellulose macromolecules, as well as the pigment deposition inside the fibers were helpful to the fibrillation prevention function of lyocell fibers. Dyed fabrics inherited the antibacterial and ultraviolet absorption properties of prodigiosins. The bacteriostatic rate against Staphylococcus aureus was above than 98.5%, and the UV protection performance was obviously improved. This technology successfully realized the color and multi-functional construction of the lyocell fabric in one step by natural pigment from microorganism.

Flame-retardant anti-fibrillation Lyocell fibers prepared by online-treatment of coagulated filament

Flame-retardant anti-fibrillation Lyocell fibers prepared by online-treatment of coagulated filament

INFLUENCES OF ALKALI PRETREATMENT ON LYOCELL WOVEN FABRIC PROPERTIES AFTER ABRASION

In this study, alkali pretreatment in various concentrations were applied to Lyocell woven fabrics to decrease the fibrillation tendency of fibers and the influences of alkali pretreatment on tensile and tearing properties of Lyocell fabrics after abrasion were investigated. Alkali pretreatment reduced fibrillation of Lyocell fibers. However, fabric shrinkage occurred because of the increased volume and damaged twisted structure of yarns due to the lateral fiber swelling. The warp/weft densities and crimp ratios increased as the alkali concentrations increased. The breaking and tearing loads of untreated Lyocell fabrics were higher than those of alkali pretreated fabrics since the strength loss caused by alkali pretreatment. The abrasive load caused fiber breakages and fiber entanglements on fabrics and decreased the both breaking and tearing loads. The weave types with long floating interlacements on the fabric surface were more severely damaged by exposing to abrasive load and resulted as higher strength reduction.

Processes and Challenges for the Manufacturing of Lyocell Fibres with Alternative Agricultural Feedstocks

Lyocell man-made cellulosic fibres (L-MMCF) have been commercially available since the mid-1990’s, with the typical feedstock prepared from tree pulp or cotton linters. In recent years, there have been advancements in the utilisation of high alpha-cellulose agricultural biomass for L-MMCF feedstock. Industrial hemp stalks offer a unique opportunity for L-MMCF since hemp is considered an environmentally conscious crop that can also help to bridge the gap in worldwide cellulose shortages; additionally, industrial hemp stalks are high in alpha-cellulose, making this an ideal feedstock for L-MMCF manufacturing. This review paper outlines the lyocell process in detail, including processes for preparation of feedstocks, pulp processing, removal of contaminants and nonessential plant components, pulp dissolution, dope preparation, and fibre spinning. Opportunities and challenges associated with the utilisation of industrial hemp stalks as an alternative feedstock are addressed through all steps of the manufacturing process. Incorporating alternative feedstock opens new perspectives for manufacturing sustainable L-MMCF.

Investigating Tear Strength in Sustainable Cotton-Lyocell Blend Siro Spun Fabrics: Twist Multiplier and Weave Type Effects

This study investigates the tear strength properties of a cotton-Lyocell blend siro spun fabric. Lyocell fibre production follows sustainable practices with a closed-loop system and renewable resources, requiring less energy and water. Furthermore, Lyocell is a biodegradable fibre, ensuring its environmentally friendly decomposition. Similarly, cotton offers durability, washability and biodegradability, making it an eco-conscious fabric alternative. Woven fabrics were created using cotton-Lyocell blend siro spun yarns with varying twist multipliers and thread densities in plain, twill and satin weaves. The tear strength of these fabrics was measured and regression analysis was conducted to investigate the impact of different parameters. The results demonstrate that twist multiplier, warp density and weft density significantly affect the tear strength of all fabric types. Furthermore, a comparison was made between the tear strength of the cotton-Lyocell siro spun fabrics and conventional ring-spun cotton fabrics and found that cotton-lyocell siro spun fabrics offer better strength properties compared to conventional ring-spun cotton fabrics. The findings of this study provide valuable insights into fabric strength factors, contributing to future research in textile development for enhanced durability and sustainability.

Turning Waste into Treasure: The Full Technological Process and Product Performance Characterization of Flushable Wet Wipes Prepared from Corn Stalk.

As a daily consumable, wet wipes are mostly synthetic fibers, which are incinerated or landfilled after use. The nanoplastics generated during this process will lead to environmental pollution. The application of flushable wet wipes, which are dispersible and fully degradable, is of great significance. The main raw material for flushable wipes is wood pulp, which has a long growth cycle and high cost. Corn is widely planted and has a short growth cycle. Currently most corn stalk is treated by incineration, which produces a lot of smoke that pollutes the environment. Therefore, using corn stalk as the raw material for flushable wet wipes, replacing wood pulp, is both cost-effective and environmentally friendly. In this study, aiming at industrial production, we explored the full process of producing flushable wet wipes from corn stalk to pulp board, then to the final wipes. The corn stalk was treated using alkali and a bleaching agent to obtain corn stalk pulp, which was then made into pulp board through the nonwoven wet-laid process. The optimal parameters for the alkali treatment and bleaching were obtained. The properties of the corn stalk pulp board were compared with the commercial wood pulp board. Further, we mixed the corn stalk pulp with Lyocell fiber to prepare wet-laid webs, which were then bonded using a chemical binder poloxamer. Then, the evenness of the web, mechanical properties, absorption, and dispersibility of the flushable wipes were characterized. Results showed that the pulp obtained using the optimal treatment process has a high yield and better whiteness. The properties of the corn stalk pulp board are comparable with the commercial wood pulp board, which can therefore potentially be replaced by the corn stalk board prepared in our study. The prepared flushable wet wipes had good evenness and their water absorption rate was more than 600%. The mechanical strength in dry and wet states achieved 595.94 N/m and 179.00 N/m, respectively. Most importantly, the wet wipes can completely disperse under the standardized testing method. A good balance of dispersibility and wet strength of the wet wipes was achieved.

Profitable and environmentally responsible recycling of fibers and reactive dyes from afterlife cotton textiles via controlled dye hydrolysis, fiber swelling and dissolution

We have developed sustainable cotton recycling to provide high-quality cellulose fibers as well as dyes. Because of the lack of simple, non-destructive, and environmentally responsible discoloration technologies, recycled cellulosic products have lower and inconsistent quality and thus limited values. For example, recycling cotton via the spinning of colored cotton into colored cellulose fibers faces challenges since dyes seriously disrupt the spinnability of cellulose dopes. Here, we demonstrate a clean technology to completely recycle all reactive dyed cotton and dyes via controlled dye hydrolysis, fiber swelling, and dissolution. Controlled dye hydrolysis cleaved the covalent bonds between reactive dyes and cellulose. Fiber swelling in N-Methylmorpholine N-oxide (NMMO)/water almost eliminated the physical interactions between dyes and cellulose. As a result, dyes, with different functional groups and chromogenic structures, were separated from cotton. The discolored cotton in NMMO demonstrated desirable spinnability without adding any new cellulose pulp. The high molecular weight makes 100% recycled lyocell fibers tougher than wood-derived lyocell. Separated reactive dyes, with unchanged chromogenic structures, demonstrate desirable dyeability as acid dyes. Recycling cotton is cost-effective to obtain cellulose pulp, the starting materials to produce lyocell, compared to the classic Kraft wood process. The NMMO was recyclable and provided consistent results of cotton discoloration for at least 5 use cycles.

3D-printed polylactide composites reinforced with short lyocell fibres – Enhanced mechanical properties based on bio-inspired fibre fibrillation and post-print annealing

3D-printed polylactide composites reinforced with short lyocell fibres – Enhanced mechanical properties based on bio-inspired fibre fibrillation and post-print annealing

EMI Shielding and Conductive Textiles Functionalized with (Ti,Cu) Nanomaterials for Biomedical Applications.

This study explores the potential of integrating thin-film technology in the design of new and effective electromagnetic interference (EMI) shielding and conductive materials for textiles and wearables. This application is of particular interest to the textile industry as it can bring new functionalities to wearables and protect humans from prolonged exposure to EM radiation. Three different thin films of pure Ti, pure Cu, and Ti-doped with Cu prepared by magnetron sputtering were used to functionalize textile knits based on cotton (code 39F) and lyocell fibers (62I). The films displayed different crystalline structures, morphologies, and topographies, which depended on their chemical compositions. The shielding effectiveness (SE) of the functionalized knits against EMI was evaluated in the frequency range of 2-8 GHz. Also, the electrical response under stress was assessed since the electrical conductivity is closely related to the EMI shielding effectiveness. The results demonstrate the feasibility of using a thin conductive layer based on Cu or Ti-Cu to improve the shield textiles with great adhesion and low thickness, providing an interesting path to improve shielding efficiency for EMI without modifying the flexibility of the textiles.

Lyocell fibre production using NMMO – A simulation-based techno-economic analysis

The demand for man-made cellulosic fibres is expected to grow in the future. One commercially-available concept to supply fibres is Lyocell manufacturing from dissolving wood pulps using N-Methylmorpholine N-oxide (NMMO) as the solvent. The literature qualitatively indicates that NMMO recycling efficiency is a key factor for profitable operation. Process design information and parameter data are however poorly available publicly to illustrate the cost factors. Therefore, systematic techno-economic analysis of a 50 kt/year Lyocell plant was conducted using steady-state process simulation and cost modeling. With the simulation models, the underlying technical process design and modelling decisions, and economic assumptions were studied. NMMO makeup need is an important cost item. The simulated makeup need is very dependent on the design of the solvent recovery system and the vapor-liquid equilibrium thermodynamic model selection. On the other hand, water use, fibre washing process design, and washing model parameterization have relatively lower impact on the cost of production. Raw material cost and capital expenses are most critical cost items when the NMMO recycling efficiency is high.

Role of sulfuric acid in thermostabilization and carbonization of lyocell fibers

Role of sulfuric acid in thermostabilization and carbonization of lyocell fibers

Valorization of beetle infected spruce to produce textile fibers and biofuels: Environmental sustainability evaluated by life cycle assessment

To achieve a viable forest-based biorefinery, both the carbohydrate and lignin parts of the raw material should be valorized. While lignin-first approaches have successfully been applied to hardwoods, where up to 50% of the lignin –close to the ‘theoretical maximum yield’– has been transformed to valuable monophenols; limited studies have targeted softwoods. Softwood lignin comprises lower amount of beta-ether bonds and this results in lower theoretical and observed yields of monophenols in reductive catalytic fractionation (RCF): below 5 wt% yield of initial biomass has been reported. In this study, we use beetle infected spruce, a softwood, as raw material. A fast fractionation was developed to give a pulp and a lignin fraction in the absence of transition metal catalysts. The carbohydrate matrix was valorized to dissolving grade pulp in 37 wt% from biomass (86% yield), and successfully spun to Lyocell fibers. The lignin fraction was dissolved in furfural –operating as green ‘solubility-enhancing-agent’– to blend lignin in inert carrier liquids to promote controlled hydrotreatment to yield biofuels in 10 wt% (60% carbon yield) from initial biomass. Life cycle assessment (LCA) of the value-chain showed improved sustainability in several footprint categories compared to cotton production. Thus, upgrading of a considered forestry waste to high value textile fibers and biofuels has been achieved: in case of lignin beyond the ‘theoretical maximum yield’. This is an important step to mitigate a future growing demand of textiles without negatively affecting irrigation or land use.

Efficient preparation of high-purity cellulose from moso bamboo by p-toluenesulfonic acid pretreatment

This work proposed a promising biorefinery method for the deconstruction of moso bamboo by using p-toluenesulfonic acid (P-TsOH) pretreatment to product high-purity cellulose (dissolving pulp). The cellulose pulp with high α-cellulose content (82.36 %) was successfully prepared for 60 min at low pretreatment temperature (90 °C) and atmospheric pressure. After the simple bleaching and cold caustic extraction (CCE) processes, the properties of cellulose pulp, such as α-cellulose content, polymerization, ISO brightness, all met the standard of dissolving pulp. In general, the cooking method through P-TsOH pretreatment can shorten the preparation time, which can effectively reduce energy consumption and chemical consumption. Therefore, this work may provide a new perspective for the green preparation of dissolving pulp that can be used to produce lyocell fiber after ash and metal ion treatment.

Quality of Fine Yarns from Modacrylic/Polyacrylate/Lyocell Blends Intended for Affordable Flame-Resistant Underwear.

Flammability testing of undergarments is a topic that is often overlooked and rarely on the list of textiles to be tested for fire safety. However, it is particularly important for professionals exposed to fire risk to investigate the flammability of underwear as its direct contact with the skin can be critical to the extent and degree of skin burns. This research focuses on the suitability of affordable blends of 55 wt.% modacrylic, 15 wt.% polyacrylate, and 30 wt.% lyocell fibres that have the potential to be used for flame-resistant underwear. The influence of modacrylic fibre linear density (standard and microfibres), ring spinning processes (conventional, Sirospun, and compact), and knitted structure (plain, 2:1 rib, 2:1 tuck rib, single pique, and triple tuck) on their properties required for thermal comfort in high-temperature environments was investigated. Scanning electron and optical microscopy, FT-IR spectroscopy, mechanical testing, moisture regain, water sorption, wettability, absorption, DSC, TGA, and flammability were tested to assess the desired suitability. The wetting time (5-14.6 s) and water absorption time (4.6-21.4 s) of the knitted fabrics have shown excellent ability to transport and absorb water compared to the knitted fabrics created from a conventional blend of 65% modacrylic and 35% cotton fibres. The afterflame and afterglow times of less than 2 s met the criteria for non-flammability of the knitted fabrics according to the limited flame spread test method. The results show that the investigated blends have the potential to be used for affordable flame-retardant and thermally comfortable knitted fabrics for underwear.