Regenerated Cellulose Fibers Research Articles

Properties, Production, and Recycling of Regenerated Cellulose Fibers: Special Medical Applications

Regenerated cellulose fibers are a highly adaptable biomaterial with numerous medical applications owing to their inherent biocompatibility, biodegradability, and robust mechanical properties. In the domain of wound care, regenerated cellulose fibers facilitate a moist environment conducive to healing, minimize infection risk, and adapt to wound topographies, making it ideal for different types of dressings. In tissue engineering, cellulose scaffolds provide a matrix for cell attachment and proliferation, supporting the development of artificial skin, cartilage, and other tissues. Furthermore, regenerated cellulose fibers, used as absorbable sutures, degrade within the body, eliminating the need for removal and proving advantageous for internal suturing. The medical textile industry relies heavily on regenerated cellulose fibers because of their unique properties that make them suitable for various applications, including wound care, surgical garments, and diagnostic materials. Regenerated cellulose fibers are produced by dissolving cellulose from natural sources and reconstituting it into fiber form, which can be customized for specific medical uses. This paper will explore the various types, properties, and applications of regenerated cellulose fibers in medical contexts, alongside an examination of its manufacturing processes and technologies, as well as associated challenges.

Wood meet MOFs: Facile, green, and highly selective adsorbent for textile wastewater

Owing to their unique physicochemical features, ionic liquids (ILs) are extensively utilized to dissolve cellulose for the preparation of regenerated cellulose fibers (RCFs) in the textile industry. However, Cu2+ is introduced during the cellulose dissolution process and gradually accumulates, seriously affecting the RCF performance and IL recovery. Herein, to achieve an efficient and selective adsorption of Cu2+ from ILs aqueous solutions, a facile and green method based on the in situ growth of zeolitic imidazolate framework-67 in wood hydrogels (ZIF-67@WH) is presented. The morphology, functional groups, crystallinity, thermal stability, and pore structure of the resulting ZIF-67@WH were investigated using various characterization techniques, and the adsorption selectivity, adsorption thermodynamics, adsorption kinetics, and recoverability were examined in depth by performing batch experiments. The ZIF-67@WH exhibits high adsorption selectivity for Cu2+ and ILs with adsorption ratios of 92.8 % and 2.2 %, respectively. The selective adsorption mechanism was elucidated by means of FT-IR, XPS, DFT, and MD. As the key for the selective adsorption, the N site in ZIF-67 dramatically promotes the coordination with Cu2+, while the adsorption for ILs mainly occurs via hydrogen bonding and van der Waals interactions with adsorption energies of –80.61 and –35.33 kcal/mol, respectively. The results demonstrate that this approach constitutes a feasible technique for the efficient separation of Cu2+ and ILs in the textile industry.

How regenerated cellulose fibers appear in the discourse on marine pollution with microplastic: a snowballing and network approach

Abstract Microplastics are prominent marine pollutants that have been investigated in various recent studies. While some of these studies mention regenerated cellulose fibers (RCFs), as part of microplastics or in close connection, other studies consider RCFs to be biodegradable by their nature and hence neglectable in context of marine pollution. This systematic literature review on the biodegradability of RCFs was conducted to investigate how such differences can be explained. An innovative snowballing-network approach has been applied for the review to gain a better understanding of historical developments of and interconnections between according strains of literature. Starting from four different papers the review fol-lowed according references and citations.
Results indicate that a consensus is lacking across research fields on the chemical character-istics of RCFs. The inconsistent use of existing terminology by some researchers, and fail-ure to make distinctions between RCFs and synthetic fibers or plastics in the results may lead to misinterpretation regarding the impacts of RCFs in the environment.
By using more accurately the existing terms and definitions, researchers could prevent read-ers from misinterpreting research results and increase their understanding of RCFs.
Biodegradation of regenerated cellulose fibers was reviewed, and consensus is that these fibers are biodegradable in all natural environments and suitable industrial settings. Con-ducting further research on the fate of RCFs and other cellulose fibers from processed con-sumer products like textiles, as well as microfibers from textiles in general, in natural envi-ronments are recommended.

Effect of eucalyptus globulus pulp properties on fock reactivity

AbstractDissolving-grade pulps serve as the primary material for producing regenerated cellulose fibers, and their utilization is steadily increasing. Despite extensive research efforts, it remains necessary to deepen our understanding of the inherent factors that impact pulp reactivity apart from the well-known degree of polymerization. The Fock reactivity test is commonly used to quantify the reactivity of cellulose pulp by measuring the percentage of cellulose that reacts with carbon disulfide. Dissolving pulps typically require a reactivity of over 90%. Hemicellulose content, intrinsic viscosity, cell wall porosity, crystallinity, and accessible area of four different pulps were characterized and distinct treatments were employed to try to separate the effect of different pulp properties and assess their effect on Fock reactivity. Hemicelluloses removal by xylanase and cold caustic treatments (86% removal) increased the Fock reactivity by 30%, from 55.7% to 71.3%. Assuming the hemicelluloses are fully accessible by the CS2, cellulose reactivity increased from 35.6% to 69.5%,but at the expense of an intrinsic viscosity decrease from 990 cm3/g to 689 cm3/g. This unexpected intrinsic viscosity decrease can be due to the cellulose de-shielding effect provoked by hemicellulose removal and some cellulose degradation during cold caustic extraction. Vibrational impact ball-milling applied on a pulp with 5% hemicellulose content notably boosted Fock reactivity by 56%, from 54% to 84.5%, but two pulp properties, intrinsic viscosity, and crystallinity, decreased concurrently due to the high-energy treatment. This phenomenon complicates identifying a direct correlation between heightened reactivity and a single parameter. To address this, endoglucanase treatment was used to separate intrinsic viscosity from crystallinity, clarifying their contributions to changes in Fock reactivity. Unfortunately, the effect of a given physical or bio/chemical pulp treatment affects more than one pulp property, always including the cellulose degree of polymerization, which has made it difficult to isolate the pulp properties that affect Fock reactivity. Several processes have been tested to obtain pulp with dissolving potential.

Forensic Discrimination of Various Subtypes of Regenerated Cellulose Fibers in Clothing Available on the Consumer Market

The discrimination of five subtypes of regenerated cellulose fibers, i.e., viscose, bamboo, lyocell, modal, and cupro, from both men’s and women’s clothing available on the prevalent apparel market was described. The examinations were conducted using optical microscopy (in transmitted white light and polarized light), scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM–EDX), and Fourier Transform Infrared Spectroscopy (FTIR). The microscopic methods revealed characteristic features of the morphological structure of the examined fibers, enabling the identification of differences between the subtypes. As a result, the microscopic methods were found to be the most effective for identifying and distinguishing between the types of examined fibers. Although the FTIR technique did not allow for distinguishing between the fiber subcategories, it contributed to the enlargement of the IR spectra databases for regenerated cellulose fibers. Based on the findings, a general scheme of the procedure for identifying the tested fibers was proposed.

Molecular insight into the dissolution-degradation process of cellulose bunch in ionic liquids

Ionic liquids (ILs) as green solvents have been utilized in dissolving cellulose and fabricating regenerated cellulose fibers. Imidazolium-based ILs with acetate or phosphate anions present advantage, due to the low viscosity and melting point, as well as its excellent ability to form hydrogen bonds (H-bonds) with the hydroxyl groups of cellulose chains. In this work, the microscopic dissolution processes of a cellulose bunch in four ILs were reproduced via molecular dynamics (MD) simulations. The cellulose bunch dissolution capabilities of these four ILs are [Emim][OAc] > [Emim][DMP] > [Emim][DEP] > [Bmim][DMP], as verified through in-situ polarized optical microscope. It is important to note that cellulose may degrade in some ILs during dissolution, affecting the performance of regenerated cellulose, while the underlying mechanism is unclear, and the strength of H-bonds formed between ILs and cellulose chains can reflect their degradation strength Combined with density functional theory (DFT) calculations, the H-bonds formed between different anions and cellulose hydroxyl groups were analyzed in depth and the order of H-bond strength is [OAc]− > [DEP]− > [DMP]−, which is different from the dissolution order of cellulose bunch in [Emim][DEP] and [Emim][DMP]. Further analysis revealed that the difference in diffusion coefficients leads to faster dissolution of cellulose in [Emim][DMP]. This study elucidates the dissolution and degradation processes of cellulose in ILs at the molecular level, offering theoretical insights crucial for the development of novel ILs that are efficient in the process of cellulose spinning.

Structure and properties of the cellulose fibres spun from imidazolium-based carboxylate functionalized zwitterionic liquid

Dissolution of cellulose without further derivatization has been an active area of research in recent years. There are still challenges in developing a commercially viable solvent system for the dissolution and regeneration of cellulose as films and fibres. We report here a process for making cellulose fibres through the dry-jet wet spinning method by utilizing aqueous zwitterionic liquid (ZIL), viz., (6-(1-(2-methoxyethyl) imidazol-3-io)-hexanoate), in which oxyethylene substituted imidazolium-based cation and a carboxylate anion is covalently tethered. Our results suggest that 11 % ZIL dope could be successfully prepared and spun under industrially viable process conditions. The resultant fibres have properties comparable to that of commercial-grade Lyocell fibres. Particularly, the cellulose fibres spun from a cellulose ZIL solution exhibited a denier of 1.2–1.6, a tenacity of 3.5–4.0 g per denier (gpd), and an elongation at break of 8–10 %, which is comparable to cellulose fibres produced using ionic liquid and N-methyl-morpholine-N-oxide (NMMO) solvent. Cellulose fibres obtained from zwitterionic liquid have a crystallinity of 60 %, which is comparable to Lyocell fibres. To the best of our knowledge, this is the first report to demonstrate the successful spinning of regenerated cellulose fibres using zwitterionic liquids with mechanical properties comparable to commercial Lyocell fibres.

Cellulose Fiber with Enhanced Mechanical Properties: The Role of Co-Solvents in Gel-like NMMO System.

Cellulose has garnered attention in the textile industry, but it exhibits limitations in applications that require high strength and modulus. In this study, regenerated cellulose fiber with enhanced mechanical properties was fabricated from a gel-like N-methylmorpholine N-oxide (NMMO)-cellulose solution by modulating the intermolecular interaction and conformation of the cellulose chains. To control the interaction, two types of co-solvents (dimethyl acetamide (DMAc) and dimethyl formamide (DMF)) were added to the cellulose solutions at varying concentrations (10, 20, and 30 wt%). Rheological analysis showed that the co-solvents reduced the solution viscosity by weakening intermolecular interactions. The calculated distance parameter (Ra) in Hansen space confirmed that the co-solvent disrupted intermolecular hydrogen bonding within cellulose chains. The solutions were spun into fiber via a simple wet spinning process and were characterized by X-ray diffraction (XRD) and universal testing machine (UTM). The addition of co-solvent led to an increased crystallinity index (C.I.) owing to the extended cellulose chains. The modulus of the resulting fiber was increased when the co-solvent concentration was 10 wt%, regardless of the co-solvent type. This study demonstrates the potential for enhancing the mechanical properties of cellulose-based products by modulating the conformation and interaction of cellulose chains through the addition of co-solvent.

An azine‐based halochromic molecular chameleon

Halochromism has a plethora of uses in the textile industry, including wound treatments and protective apparel. Reactive dye’s fastness and a wide variety of hues, from bright to dull, make it ideal for coloring cotton and other regenerated cellulose fibers. It is also fundamentally paramount importance to determine the freshness of packaging foods. In this study, a halochromic probe, 4,4′-((1E,1′E,3E,3′E)-hydrazine-1,2-diylidenebis(prop-1-en-1-yl-3-ylidene))bis(N, N-dimethylaniline), HDBD, has been introduced utilizing a simple condensation reaction. Through the protonation and deprotonation process with the addition of acid and base in the non-aqueous medium, HDBD shows visual colorimetric as well as ratiometric UV–visible absorption spectral change. A colorimetric paper strip-based experiment has been demonstrated to detect trace amounts of acid and its reversibility with bases in non-aqueous solvents. Further, a dip-stick experiment was also carried out for the detection of acid-base vapor in a wide range of concentrations. Furthermore, the overlapping indicator method is explored to estimate acid dissociation constants in the non-aqueous medium. Moreover, we have constructed the INHIBIT (INH) and IMPLICATION (IMP) molecular logic gates exploring the reversibility of HDBD due to the cascade introduction of acid-base as chemical encoded inputs. Utilizing a reversible and reproducible detecting method, we have constructed a molecular-scale additional memory device that demonstrates binary logic “Writing-Reading-Erasing-Reading” and “Multi-write” functions. This finding provides a new way for designing acid-base indicators, which could estimate the acid dissociation constants of various acids in the non-aqueous environment which is fundamentally important in the field of acid-catalyzed organic synthesis.

Fabrication of double-shell microcapsule encapsulated with wormwood essential oil and its application in regenerated cellulose fiber

Fabrication of double-shell microcapsule encapsulated with wormwood essential oil and its application in regenerated cellulose fiber

Spin-dyeing of cellulose fibres with vat dyes using the Ioncell process

Estimated 20 % of global clean water pollution is attributed to textile production. Dyeing and finishing processes use an extensive amount of water and chemicals, and most of the effluents and wastewater is released into the environment. In this study, we explore spin-dyeing of man-made cellulosic fibres (MMCFs) with vat dyes using the Ioncell process, circumventing the ubiquitous use of fresh water and potentially reducing effluents streams to a great extent. Spin-dyeing is an established process for synthetic polymers but is not common for MMCFs. Regenerated cellulose fibres were produced through dissolution of dissolving pulp in the ionic liquid 1,5-diazabicyclo[4.3.0]non-5-ene acetate. The produced fibres were processed into yarn and a jersey fabric was knitted. Mechanical and colour fastness properties were tested. The fibres properties were also assessed through SEM, birefringence, and crystallinity measurements. Fibres with excellent mechanical properties (tenacity higher than 50 cN/tex) and colour fastness were produced, with most samples receiving the highest or next highest performance grade. The spun-dyed fibres also hold great potential to be recycled themselves without colour change or loss in colour intensity. Textiles with colours produced in large quantities such as black or navy blue could be the first market entry point.

High tensile regenerated cellulose fibers via cyclic freeze-thawing enabled dissolution in phosphoric acid for textile-to-textile recycling of waste cotton fabrics

Recycling of waste cotton fabrics (WCFs) is a desirable solution to address the problems brought up by fast fashion, but it remains challenging due to inherent limitations in preparing stable and spinnable dopes by dissolving high molecular weight cellulose efficiently and cost effectively. Herein, we show that despite the prevailing concerns of cellulose degradation via glycosidic hydrolysis when dissolved in acids, fast and non-destructive direct dissolution of WCFs in aqueous phosphoric acid (a.q. PA) could be realized using a cyclic freeze-thawing procedure, which combined with subsequent adjustment of degree of polymerization (DP) and degassing yielded stable and spinnable dopes. Regenerated cellulose fibers (RCFs) with favorable tensile strength (414.2 ± 14.3 MPa) and flexibility (15.4 ± 1.5 %) could be obtained by carefully adjusting the coagulation conditions to induce oriented and compact packing of the cellulose chains. The method was shown to be conveniently extended to dissolve reactively dyed WCFs, showing great potential as a cheap and green alternative to heavily explored ionic liquids (ILs) and N-methylmorpholine-N-oxide (NMMO)-based systems for textile-to-textile recycling of WCFs.

A regenerated cellulose fiber with high mechanical properties for temperature-adaptive thermal management

The escalating global population has led to a surge in waste textiles, posing a significant challenge in landfill management worldwide. In this work, ionic liquid 1-butyl-3-methylimidazole acetate ([Bmim]OAc) and DMF (N, n-dimethylformamide) were used as solvents to dissolve waste denim fabric, then vanadium dioxide (VO2) nanoparticles were introduced into the spinning solution, and cellulose fibers were regenerated by dry-wet spinning process, to promote the recycling of waste cotton fabric. Finally, regenerated cellulose fibers with high added value were prepared by dry-wet spinning. Through this innovative strategy, on the one hand, because VO2 can form a large number of hydrogen bonds between the regenerated cellulose molecules, and realize the cross-networking structure of the molecular chains inside the fiber, the mechanical properties of the regenerated cellulose fibers are enhanced. On the other hand, due to the thermal phase transformation characteristics of VO2, it also endows the regenerated cellulose fiber unique intelligent temperature control function. Compared with the pristine regenerated fiber, the tensile stress of the regenerated fiber after adding VO2 nanoparticles (F-VO2) increased by 25.6 %, reaching 158.68 MPa. In addition, the F-VO2 fibric provides excellent intelligent temperature control, reducing temperatures by up to 6.7 °C.

Degradation of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Reinforced with Regenerated Cellulose Fibers.

PHBV is a promising plastic for replacing conventional petroleum-based plastics in the future. However, the mechanical properties of PHBV are too low for use in high-stress applications and the degradation of the polymer limits possible applications. In this work, the mechanical properties were, therefore, increased using bio-based regenerated cellulose fibers and degradation processes of the PHBV-RCF composites were detected in accelerated aging tests under various environmental conditions. Mechanical, optical, rheological and thermal analysis methods were used for this characterization. The fibers significantly increased the mechanical properties, in particular the impact strength. Different degradation mechanisms were identified. UV radiation caused the test specimens to fade significantly, but no reduction in mechanical properties was observed. After storage in water and in aqueous solutions, the mechanical properties of the compounds were significantly reduced. The reason for this was assumed to be hydrolytic degradation catalyzed by higher temperatures. The hydrolytic degradation of PHBV was mainly caused by erosion from the test specimen surface. By exposing the regenerated cellulose fibers, this effect could now also be visually verified. For the use of regenerated cellulose fiber-reinforced PHBV in more durable applications, the aging mechanisms that occur must be prevented in the future through the use of stabilizers.

Development of a Predictive Model for the Thermal Conductivity of Natural Fiber Insulation: A Novel Approach for Quality Control

ABSTRACT Natural fiber insulation materials can offer a sustainable alternative to mineral and petrochemical-based insulation materials when suitable raw materials and appropriate production processes are considered. Within the scope of our research, natural fibers like cotton, flax, hemp, wool, and coir, as well as regenerated cellulose fiber, were processed into insulation materials and examined concerning their thermal conductivity. We demonstrate that simple test methods for fiber fineness measurement with air-flow methods such as Airflow and Shirley can facilitate incoming inspection and process monitoring for insulation manufacturers. Based on these measurements, a simple model was developed to estimate the thermal conductivity based on the fineness measurements of the raw materials. The model developed on the natural fibers for lower densities was tested on a glass fiber insulation material to check its suitability. The slight deviations achieved between the experiment and the calculation verify the practicability of the concept.

Co-modification of engineered cellulose surfaces using antibacterial copper-thiosemicarbazone complexes and flame retardants

Lyocell fibers, the most successful regenerated cellulose fibers, have already attracted much attention. However, the use of traditional Lyocell fibers in the field of personal protective equipment (PPE) is limited, due to the lack of antibacterial properties. Additionally, the flame-retardant properties of Lyocell fibers are also required for the specific applications. Here, we co-conjugated phosphorus flame retardants and copper-thiosemicarbazone complexes with antibacterial performance on Lyocell fibers through chemical crosslinkers. The chemical composition and morphology of our engineered Lyocell fibers were fully characterized, and their mechanical properties were also maintained. Flame retardants can import flame-retardant properties (LOI: 25.0 % - 25.7 %) to Lyocell fibers, which also show promising antibacterial activity, suppressing Escherichia coli (GIR: 20.51 % - 66.67 %) and Staphylococcus aureus (GIR: 74.19 % - 93.54 %). Such an improved sustainable formulation can be used to produce the next-generation of Lyocell-based PPE, to meet the demand for the antibacterial and flame-retardant properties of fibers in special applications.

A strategy for introducing biomass naringin molecules into regenerated cellulose fibers: Construction of both low fibrillation tendency and high strength lyocell fibers

Lyocell fiber is regarded as one of the most representative green fibers, which has higher strength than other regenerated cellulose fibers, but is easily fibrillated when produced. Here, we developed a strategy to strengthen lyocell fiber by the strong interaction between the small molecules of biomass and polymeric cellulose chain networks. The green biomass naringin molecules containing phenolic hydroxyl structures are introduced into the solvent (N-methyl morpholine-N-oxide, NMMO) system of producing lyocell fiber, and the rational arrangement of naringin and cellulose molecular chains is precisely controlled through fiber-forming process of dry-jet-wet spinning and wet-drafting. Due to the interaction of strong hydrogen bond between naringin and cellulose molecules, the strength, toughness and Young’s modulus of the obtained composite fibers reached 500.78 ± 33.57 MPa, 28.16 ± 4.65 MJ/m3 and 23.06 ± 1.01 GPa, respectively, which were 86.96 %, 44.86 % and 48.97 % higher than those of pure lyocell fibers. In addition, naringin molecules have two directional (the longitudinal and transverse direction) bonding effects, which not only improves the mechanical performance of the fiber, but also reduces the fibrillation. The simultaneously improvement of mechanical performance and the reduction of fibrillation tendency are unprecedented in related studies, which contributes to the production of better performance lyocell fibers.

Asymmetric ionic bond shielding encountering with carboxylate capturing metal ions for enhancing the flame retardant durability of regenerated cellulose fibers

Enhancing the flame retardancy and durability of cellulose fibers, particularly environmentally friendly regenerated cellulose fibers types like Lyocell fibers, is essential for advancing their broader application. This study introduced a novel approach to address this challenge. Cationic-modified Lyocell fibers (Lyocell@CAT) were prepared by introducing quaternary ammonium structures into the molecular chain of Lyocell fibers. Simultaneously, a flame retardant, APA, containing -COO−NH4+ and -P=O(O−NH4+)2 groups was synthesized. APA was then covalently bonded to Lyocell@CAT to prepare Lyocell@CAT@APA. Even after undergoing 30 laundering cycles (LCs), Lyocell@CAT@APA maintained a LOI value of 37.2 %, exhibiting outstanding flame retardant durability. The quaternary ammonium structure within Lyocell@CAT@APA formed asymmetric ionic bonds with the phosphate and carboxylate groups in APA, effectively shielding the binding of Na+ ions with phosphate groups during laundering, thereby enhancing the durability. Additionally, the consumption of Na+ ions by carboxylate groups further prevented their binding to phosphate groups, which contributed to enhance the durability properties. Flame retardant mechanism analysis revealed that both gas and condensed phase synergistically endowed excellent flame retardancy to Lyocell fibers. Overall, this innovative strategy presented a promising prospect for developing bio-safe, durable, and flame retardant cellulose textiles.

Biodegradable composites fabricated using recycled poly(lactic acid)-based single-use coffee cup and regenerated cellulose fiber

ABSTRACT A series of biodegradable composites, including maleic acid-grafted recycled poly(lactic acid) (g-rPLA) and chemically modified lyocell (m-lyocell), were successfully synthesized. The rPLA was obtained from waste PLA-based single-use coffee cups. The storage modulus at −20°C of g-rPLA was increased from 1920 MPa for pure PLA to 3370 MPa for 5 wt% g-rPLA/m-lyocell composites, which is more than 75% enhancement. The number-average molecular weight after photodegradation for 60 days of g-rPLA and 5 wt% g-rPLA/m-lyocell composites was decreased by about 67.12% and 26.17% as compared to the samples before photodegradation, respectively. The results of photodegradations for composites indicate that the change of number-average molecular weight after photodegradation decreased by increasing the loading of m-lyocell. This result suggests that the existence of m-lyocell improved the UV protection ability of the g-rPLA. With the enhancement of mechanical properties and UV protection ability, this work provides an appropriate approach for the applications to reuse the waste PLA-based single-use coffee cups.

Scanning WAXS microscopy of regenerated cellulose fibers at mesoscopic resolution.

In this work, regenerated cellulose textile fibers, Ioncell-F, dry-wet spun with different draw ratios, have been investigated by scanning wide-angle X-ray scattering (WAXS) using a mesoscopic X-ray beam. The fibers were found to be homogeneous on the 500 nm length scale. Analysis of the azimuthal angular dependence of a crystalline Bragg spot intensity revealed a radial dependence of the degree of orientation of crystallites that was found to increase with the distance from the center of the fiber. We attribute this to radial velocity gradients during the extrusion of the spin dope and the early stage of drawing. On the other hand, the fiber crystallinity was found to be essentially homogeneous over the fiber cross section.