Viscose Research Articles

Preparation of low-temperature soluble modified starch by introducing maleate and sulfonate groups under dry conditions to enhance adhesion to wool and viscose fibers

Preparation of low-temperature soluble modified starch by introducing maleate and sulfonate groups under dry conditions to enhance adhesion to wool and viscose fibers

Measurement of tensile properties of selected rovings

This article is focused on measuring the tensile properties of chosen fibre materials, such as flax, alkali resistant glass or viscose. All selected materials were tested both pure and impregnated using epoxy resin. In this article, the tensile strength and the Young’s modulus were observed. Young’s modulus was measured using Digital Image Correlation. The suitability of the location of small speckle pattern targets, which are used for measurements of deformations, was first verified on the viscose fiber samples. Targets were applied directly to the roving and further to the sleeves made of epoxy resin used to fix samples in the test equipment. After the evaluation, the selected location was then applied to the selected types of rovings. Finally, the measured results were compared.

Micro– and mesoplastic pollution in the surface water and nekton from the eastern Indian ocean: Spatiotemporal variation, correlation and risk assessment

The pollution of micro– and mesoplastic (MMP) in the Eastern Indian Ocean (EIO) remains poorly understood. The present study revealed that MMP abundance in nekton from EIO in 2022 (mean: 2.30 ± 0.39 items individual−1 and 1.81 ± 0.54 items g−1) was significantly higher than that in 2021 (mean: 1.60 ± 0.22 items individual−1 and 0.80 ± 0.13 items g−1). In contrast, MMP abundance in surface water varied insignificantly between 2021 (mean: 0.04 ± 0.01 items m−3) and 2022 (mean: 0.05 ± 0.02 items m−3). The rise in predominant polymers—polypropylene (PP), rayon (RA), and polyester (PES)—in nekton from 2021 to 2022 may suggest increased pollution from face masks and home textiles along coastal regions. Notable spatial variation in PP and RA between the northeastern and southeastern regions was observed only in nekton, suggesting they are better indicators of MMP spatiotemporal variation than surface water. Shadow driftfish ingested more MMPs than purpleback flying squid and mackerel scad, likely due to its deeper habitat. By simultaneously considering color, composition, and shape, integrated MMP analysis showed insignificant correlation between MMP pollution in surface water and nekton, suggesting that nekton may ingest MMPs through multiple pathways beyond surface water. Risk indices for surface water and nekton reached moderate to upper levels globally, emphasizing the need for continued monitoring in the EIO. Epoxy resin, rubber, and PP + acrylic were identified as the most hazardous polymers, providing a valuable basis for developing effective strategies to mitigate plastic pollution.

Water treatment of recirculating aquaculture system (RAS) effluent water through microalgal biofilms

This research studied the growth of microalgae (Chlorella vulgaris and Phaeodactylum tricornutum) on a biofilm reactor using effluent water from salmon production in a recirculating aquaculture system (RAS). RAS effluent water contains considerable amounts of nitrate and small amounts of phosphate, that stem from dissolved excess feed and fish faeces. In microalgae growth experiments, we tested a twin-layer biofilm reactor, which has one layer for substrate distribution (RAS effluent water-based medium) and adhered onto that, a carrier layer for biofilm cultivation. First, we tested five different carrier materials (newsprint, filter paper, polypropylene, viscose/polyester mix, viscose) to assess the microalgae's attachment ability of the material, where the viscose fibre material proved to be the most suitable. The biofilm reactor design had to be improved for saltwater suitability, as water evaporation caused changes in salinity and nutrient concentrations and ultimately led to the formation of salt crusts on the biofilm and clogging of the irrigation system. A dilution of the medium with osmosis water compensated the evaporation rate and a technical improvement of the irrigation system established stable cultivation conditions. The biofilm reactor was then tested for all three water types (Chlorella for freshwater, Phaeodactylum for brackish water and saltwater) that are discharged during a RAS production cycle for salmon. Microalgae paste was used for inoculation of the biofilm carrier material and after a short maturation phase the biofilm reactor was harvested every three days. This study demonstrated that a complete uptake of nitrate and phosphate from RAS effluent water through microalgae cultivation is possible, and the biofilm reactor is able to handle changes in nutrient concentrations and salinity. Biomass productivity for Phaeodactylum cultivated on brackish RAS medium was highest (15.28 g m−2 d−1), compared to saltwater RAS medium (4.35 g m−2 d−1) and Chlorella on freshwater RAS medium (4.25 g m−2 d−1).

Rapid surface acetylation of cellulosic materials at room temperature by immersion method

Regulating the surface hydrophobicity of cellulosic materials via surface acetylation can greatly extend their applications. However, most of the existing surface acetylation methods for cellulosic materials are time-consuming and costly. Herein a simple but practical immersion method for the rapid surface acetylation of cellulose materials was reported, which involved soaking cellulosic materials in alkaline aqueous solution followed by immersed them in vinyl acetate. Results showed that simply wetting the surface of cellulosic materials with aqueous alkaline solutions can satisfy their surface acetylation requirement, and the consumption of esterifying agent can be significantly reduced. The immersion method can rapidly improve the surface properties of the cellulosic materials at room temperature within minutes and which is highly attractive to the surface acetylation of cellulose fibers. The moisture regain of the viscose filament obviously decreased after surface acetylation. When the surface acetylated viscose fiber was used as cigarette filter, the total particulate matter in the filtered cigarette smoke significantly reduced from 11.03 mg/cigarette to 6.03 mg/cigarette. The products are promising alternatives to the existing cigarette filters.

Effect of surface charge on mechano-bactericidal activity of cellulose nanocrystals constructed chevaux-de-frise and meat preservation

The nanostructured insect wings have inspired the development of antimicrobial surfaces with mechano-bactericidal activity. For the first time, a chevaux-de-frise-like nanostructure was fabricated through the coating of cellulose nanocrystals (CNC) onto regenerated cellulose (RC) films via vacuum filtration and the impact of contact time, temperature, and surface topography on eliminating foodborne bacteria was examined. Herein, our focus is to explore in more detail how the surface charge of CNC affects the mechano-bactericidal activity and the performance of chevaux-de-frise-like nanostructure in meat preservation. CNC with neutral (weak), negative, and positive charges were prepared by hydrochloric acid hydrolysis (HCNC), TEMPO oxidation (TCNC), and amination (ACNC), respectively, and showed similar reinforcing effects on the tensile strength (increased from 74.23 ± 1.20 to about 100 MPa) and water vapor barrier property (reduced from 1.83 ± 0.08 to about 1.20 × 10−7 g m−1 h−1 Pa−1). Among them, RC-ACNC showed the highest log reduction against Escherichia coli (0.83 ± 0.06) and Staphylococcus aureus (0.69 ± 0.04) after 5 min contact, respectively, indicating the important role of attractive force in fast eliminating bacteria upon contact. It was worth noting that, during the meat preservation test, all three CNC-coated RC films exhibited a similar 0.4 log reduction of bacteria after day 4, likely due to the same physical attachment with an extended contact time. Therefore, the construction of chevaux-de-frise nanostructure from CNC on food packaging provides a sustainable strategy to contribute to preventing bacterial growth.

Kapok/regenerated cellulose based carbon aerogel prepared at a low-temperature carbonization for oil/water separation

With the requirement of sustainable development in modern society, selective filtration and separation of oils and organic solvents from polluted wastewater is a critical and very important goal. Herein, a novel hydrophobic and oleophilic cellulose-based carbon aerogel composed of kapok fiber/regenerated cellulose was prepared at a low-temperature carbonization technique (300 ℃) directly using kapok and hardwood pulp as raw material, the N-methyl N-oxide monohydrate (NMMO·H2O) as a green cellulose solvent, and NH4H2PO4 (ADP) as a carbonization promotor, which is denoted as AX-KRCA(AX: A indicates the ADP used, x is the concentration of ADP solution (g/L)) The regenerated cellulose (RC) was converted from hardwood pulp via NMMO·H2O treatment, and further combined with kapok fiber to form a 3D porous structure. By adding ADP, AX-KRCA can be rapidly dehydrated into carbon at 300 ℃, which not only saves energy consumption but also retains the basic form of kapok fiber and regenerated cellulose, making it have excellent compressibility, elasticity, and fatigue resistance. The ultra-light porous AX-KRCA samples can be an efficient oil/water adsorbent, with an adsorption capacity from 98.0 to 232.1 g g−1 for various oils, and can maintain 87.3 % adsorption capacity after 20 cycles and 99.6 % separation efficiency after 5 times of filtration.

Optimized production and comparative analysis of microcrystalline cellulose particles from jute and viscose fiber wastes

Optimized production and comparative analysis of microcrystalline cellulose particles from jute and viscose fiber wastes

Analysis of a constant-volume diafiltration system with the ability to remove lithium cations when using poly(2-acrylamido-2-methyl-1-propanesulfonic acid) in water

This study describes the synthesis of a poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) and its application for the removal of Li+ in water using a constant-volume diafiltration system. PAMPS with molecular weights exceeding 100 kDa (88 % w/w), polymerisation yields of 97 % and high acidity was obtained. A block experimental design characterized the diafiltration system reporting: Regenerated cellulose (RC) and polyethersulfone (PES) ultrafiltration membranes with a molecular cut-off of 100 kDa can retain up to 1 % Li+ ions through surface charges. But when PAMPS 2000 kDa was used, 89 % of Li+ was removed (%R). Permeate flux (Js) decreases with increasing PAMPS:Li+ ratio, whereas the %R value increases. The filtration process is controlled by diffusion mechanisms according to the Peclet dimensionless number. Using PAMPS 100 kDa with a PAMPS:Li+ ratio (20:1), %R decreases to 76 %, whereas Js increases slightly. PAMPS can be reused 3 consecutive times, maintaining a Li+ cation rejection efficiency of >60 %. Additionally, it was found that the percentage of Li+ rejection capacity exercised with PAMPS is reduced to 60 % when Ca2+, K+, Mg2+ and Na+ cations are present.

Wearing Quality of Ribbed Knits Made from Viscose and Lyocell Fibers for Underwear

As an alternative to cotton, viscose and lyocell fibers are suitable for the production of knitted next-to-skin underwear. Despite the advantages of a more environmentally friendly production process and valuable properties, the consumption of lyocell fibers is significantly lower compared to viscose fibers. The applicability of viscose and lyocell fibers in the production of ribbed knits for underwear is insufficiently researched, as is the influence of unconventionally spun yarns on their wearing properties. This study, therefore, investigates the possibilities of using lyocell fibers in the production of novel knitwear with improved properties compared to viscose and conventional cotton knitwear and determines their wearing quality. In this context, two sets of circular 1 × 1 rib jersey fabrics were produced from three types of differently spun viscose and lyocell yarns. The quality of the dry relaxed and wet processed knitted fabrics was evaluated by determining their structure, absorbency, air permeability, and dimensional stability, as well as their tensile, abrasion, and pilling properties, all in comparison to cotton knitted fabric produced under the same conditions. The results showed that lyocell rib knits have better structural uniformity, tensile properties, dimensional stability, air permeability, lower abrasion resistance, and comparable moisture absorbency and pilling propensity compared to viscose knits.

Studies on the effect of reactive dye on jute and jute blended fabrics

Jute is generally not dyed with reactive dye though it is a cellulosic fiber. While jute is dyed with basic dye, but cotton, viscose, and other cellulosic fibers are frequently dyed with reactive dye. In this study, a novel method for dying blended jute fabrics with reactive dye after bleaching them is presented. Two different reactive dye colors were used to treat this blended jute fabric. By contrasting samples of non-dyed grey blended jute fabric, the GSM, Water uptake percentage, and FTIR of dyed fabric were examined. It has been observed that the dyed sample's GSM (average 76) is higher than the grey fabrics GSM (average 65) due to the chemical modification of grey blended jute fabric. Blended jute fabric has a lower water absorption percentage while dyed sample has a higher absorption percentage such as 150% in 40 min and 145% in 140 min. Due to chemical modification of the surface of the blended jute fabrics, the FTIR spectrum report reveals that –OH group peak appeared in the wave number of 3291 cm−1 and the dyeability of the fabric is significant based on peak analysis.

Nanostructured Affinity Membrane to Isolate Extracellular Vesicles from Body Fluids for Diagnostics and Regenerative Medicine.

Electrospun regenerated cellulose (RC) nanofiber membranes were prepared starting from cellulose acetate (CA) with different degrees of substitution. The process was optimized to obtain continuous and uniformly sized CA fibers. After electrospinning, the CA membranes were heat-treated to increase their tensile strength before deacetylation to obtain regenerated cellulose (RC). Affinity membranes were obtained by functionalization, exploiting the hydroxyl groups on the cellulose backbone. 1,4-Butanediol-diglycidyl ether was used to introduce epoxy groups onto the membrane, which was further bioconjugated with the anti-CD63 antibody targeting the tetraspanin CD63 on the extracellular vesicle membrane surface. The highest ligand density was obtained with an anti-CD63 antibody concentration of 6.4 µg/mL when bioconjugation was performed in carbonate buffer. The resulting affinity membrane was tested for the adsorption of extracellular vesicles (EVs) from human platelet lysate, yielding a very promising binding capacity above 10 mg/mL and demonstrating the suitability of this approach.

Hydrothermally rearranged cellulose membranes for controlled size sieving

Biodegradable polymers are important for reducing pollution and promoting sustainability as they break down more easily than traditional petroleum-based polymers. One such polymer is regenerated cellulose (RC), which is widely used in water purification and pharmaceuticals due to its chemical resistance and hydrophilicity. Since its direct use of cellulose is limited by its insolubility, derivatives like cellulose acetate (CA) are first converted through a regeneration process back into RC to make use of its functional properties. During this process, however, the membrane structure may be compromised, impairing its separation performance. Here we show that simply soaking CA membranes in hot water before regeneration significantly improves the structural integrity of RC membranes, retaining the sieving properties. The pretreatment causes planar shrinkage without disrupting the general characteristics of cellulose, allowing for sole adjustment of pore size. This straightforward approach enables precise tuning of membrane pore properties to suit specific application, such as adjusting pore size for efficient sieving of materials with particular molecular masses, all while maintaining high water permeance. Our findings suggest that hydrothermal processing has the potential to enhance the filtration performance of RC membranes and broaden their range of applications.

The conformance control and enhanced oil recovery performance of CO2 foam reinforced by regenerated cellulose

CO2 foam flooding is one of the most promising technologies for conformance control and enhanced oil recovery (EOR) in heterogenous tight oil reservoirs. However, it is challenging to maintain foam stability at in-situ high temperature and high salinity reservoir conditions, thus seriously limiting the flooding efficiency. Herein, a new approach of CO2 foam reinforced by regenerated cellulose (RC) was proposed and evaluated by multiple light scattering method and microscopic detection; afterwards, the conformance control and EOR performances were evaluated via flooding experiments at representative reservoir conditions of 85 °C and 59737.6 mg/L, using artificial micro-models and heterogenous core test. Results have demonstrated that: Compared with CO2 foam without RC, the foam with 1 % RC could elongate the foam half-life by ∼30 times (i.e., from 18 to 543 mins) and the drainage half-time by ∼4 times (i.e., from 2.5 to 9.5 mins), respectively; For the conformance control, the CO2 foam flooding with RC improved the sweep efficiency from the respective 42.4 % and 15.8 % to 95.4 % compared with water flooding and CO2 flooding in the micromodel experiments; the CO2 foam with RC increased the injection pressure from 0.20 to 3.1 MPa in the core flooding experiments, suggesting the diversion of fluid from high permeable to low permeable zone. In terms of the EOR, the CO2 foam flooding with RC improved the oil recovery from the respective 29.7 % and 12.9 % to 92.3 % in contrast with water flooding and CO2 flooding in micro-flooding experiments and from 35.5 % to 56.4 % by core-flooding experiments; the underlying mechanisms are attributed to oil emulsification, rock wettability alteration and foam deformation. These insights provide new approaches to maintain foam stability, improve conformance control and EOR performances in heterogenous tight oil reservoirs under harsh conditions.

Carboxymethylation of viscose and cotton fibers: comparisons of water retention and moisture sorption

The aim of the work was to compare the water retention and moisture sorption of viscose (CV) and cotton (Co) fibers carboxymethylated from aqueous media, in presence of NaOH, with sodium monochloroacetate. It was shown previously that under the same treatment conditions, the degree of carboxymethylation was higher in CV and so was the depth within fiber structures to which the carboxymethylation reactions occurred. It was also shown previously, that in terms of their capacity for sorption of a cationic dye (methylene blue), the Co performed better than CV. In this work, the same fibers were tested for their water retention and moisture sorption propensities. The two were sensitive both to the degree of carboxymethylation and the inherent properties of fibers (accessibility, degree of swelling, hornification). But the moisture sorption levels were less sensitive to the degree of carboxymethylation and more to inherent fiber properties whereas the reverse was observed for water retention. In contrast to the prior observations with dye sorption, CV performed better than Co in both moisture sorption and water retention. The poor performance of CV in dye sorption was attributed to the greater depth of carboxymethylation within the fibers that hindered dye permeation, but the same feature was observed to result in better performance (water retention) or not to hinder performance (moisture sorption). These observations highlight the contrasting effects that may arise, of a given set of treatment parameters (fiber type, alkali level in treatment), on efficacy of the product performance.

The role of carboxyl and cationic groups in low-level cationised cellulose fibres investigated by zeta potential and sorption studies

The anionic nature of both cellulose fibres and reactive dyes prevents substantial exhaustion of dye from the dyebath, which is at neutral pH before alkali is added to initiate dye fixation. Conventionally, salt is added to minimize the electrostatic repulsions that interfere with dye sorption, but that increases salt loads in effluents. An alternative is to affix cationic agents on the cellulose to overcome the inherent anionic charge, but that has generally been observed to result in uneven dye sorption. The focus of investigations in this work is to examine the influence of the ratio of charges on cellulose (of affixed cationic charges to inherent anionic charges) on the extents and evenness of dye sorption. The cationisation agent 3-chloro-2-hydroxypropyl-N,N,N-trimethylammonium chloride (CHPTAC) was grafted on loose viscose fibres to yield 12 to 185 mmol kg−1 cationic group content on the fibre that exhibited an inherent carboxyl group content of 68 mmol kg−1. Three different dyes (of varying molecular sizes and anionic group content) were employed for examination of sorption profiles. The results from both zeta potential measurements and dye sorption profiles showed evidence of limited dye uptake until the cationic group content in fibres exceeded that of the inherent carboxyl groups. Thereafter, an uptick in dye sorption was observed, with dye sorption levels increasing with rise in degree of cationisation. There were differences between the dyes in their degrees of sorption, which appear correlated with their molecular sizes.

Valorization of hemicellulose waste streams for moisture barrier coatings and hydrophobic films

Replacing plastics with renewable and environmentally friendly substitutes is becoming ever more critical as we begin to realize the consequences of their negative impacts on the environment. Plant polysaccharides are the most abundant biopolymers on Earth, and hemicelluloses like xylan that are enriched in many agro-industrial waste streams have vast potential as eco-friendly building blocks for polymer science and engineering. However, xylan is one of the less studied natural polymers for applications that are relevant to the synthetic plastics and polymeric materials markets. Hemicellulose isolated from viscose and Lyocell fiber mills is largely seen as a waste product due to difficulties arising from the potential for structural heterogeneity and its lack of solubility after enrichment. In this work, we developed a strategy to valorize hemicellulose by functionalization with octyl isocyanate to achieve solubility and thermoplastic/hydrophobic properties. Xylan isolated from dissolving pulp waste streams was successfully functionalized with octyl isocyanate in DMSO at an estimated 79% hydroxyl conversion. Reaction parameters, including temperature, time, and stoichiometry were optimized for each reaction. The resultant carbamates of xylan oligo- and monosaccharides have good solubility in chloroform and impressive hydrophobic film forming properties yet retain the composability properties desired for renewable materials that are envisioned to enter the circular bioeconomy. Functionalization of xylan with an aliphatic chain through formation of an aliphatic carbamate is not expected to harbor the same toxicity or carcinogenic characteristics as the reactive isocyanate it is derived from, and thus should not inherently restrict these materials for use in diverse packaging applications. These modified physical properties show that xylan from agro-industrial waste streams has considerable potential to replace petroleum-based feedstocks in the existing packaging industry. In the future, we will continue to further develop strategies for valorization of these materials.Graphical

The synergistic effect of graphene oxide and flame-retardant fabrics

This study aims to explore the synergistic flame retardancy mechanism of graphene oxide (GO) and flame-retardant textiles. The flame-retardant properties of fabrics were evaluated through combustion behaviors test, scanning electron microscope (SEM), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), as well as Attenuated Total Reflection Flourier Transformed Infrared Spectroscopy (FTIR-ATR). The result of this study demonstrated that the addition of GO enhanced the fabric’s flame-retardant performance. GO’s excellent thermal conductivity synergizes with phosphazene derivatives promoting denser carbon layers formation. The dense char layer can isolate heat and oxygen to achieve the flame-retardant effects. Flame-retardant viscose fibers (FRVF)/flame-retardant polyacrylonitrile (FRPAN)/GO fabrics formed a denser carbon layer during burning, which provided heat insulation and oxygen barrier functions. The surface of FRVF/Cotton/GO fabrics had a porous carbon layer structure that isolated oxygen and prevented heat transfer. Adding GO improved the flame-retardant properties of both fabrics, although their flame-retardant mechanisms were different. GO has promising potential as a flame retarding nano-additive in composite fabrics.

Synergistic demulsification of oil-in-water emulsion using bidirectional pulse electric field and fiber coalescence

The methods of demulsification using bidirectional pulsed electric field (BPEF) and fiber coalescence exhibit limited effectiveness under conditions of high emulsification degree of oil-in-water (O/W) mixture or low oil content. However, there is an urgent requirement for efficient O/W emulsion separation. This study investigated the synergistic demulsification of oil-in-water emulsion using BPEF combined with fiber coalescence. It explored the impact of coalesced fiber parameters, output parameters of bidirectional pulse power supply, and water quality parameters on the demulsification performance of O/W emulsion. The demulsification performance of BPEF coupled with viscose fiber was superior to that of coupling polytetrafluoroethylene (PTFE) fiber, and the 10 % fiber filling rate exhibited a better synergistic demulsification effect than the 5 % fiber filling rate. The optimal synergistic demulsification performance was achieved with a 10 % viscose fiber filling ratio, 400 V pulse voltage, 50 Hz frequency and 30 % duty ratio. The O/W emulsion with an oil content of 4100 mg/L could be reduced to 9.28 mg/L, resulting in a demulsification efficiency of 99.77 %, which was 55.98 % higher than that of BPEF. The study showed that utilizing BPEF in conjunction with fiber coalescence could be a promising approach for synergistic demulsification of O/W emulsions.

Degradation of Biodegradable Nonwoven Mulches in the Winter Period.

An open field experiment from November 2022 to May 2023 in Croatia, which is characterized by a continental humid climate, evaluated nonwoven mulches made from viscose, jute, and hemp fibres blended with PLA fibres. The blends of viscose and jute fibres (90:10, 80:20, and 70:30 ratios) were produced using mechanical web formation on cards with needle punching for bonding webs. Additionally, hemp fibres were blended with PLA fibres in a ratio of 80:20. Winter conditions caused significant structural changes in the mulches, including shrinkage, increased mass per unit area, thickness, and reduced air permeability. The amount of PLA fibre in the nonwoven mulch blends significantly affected nonwoven fabric structure change during exposure to winter conditions. After 180 days, the breaking force of all mulches increased by 30% to 277%. The soil beneath jute and hemp mulches maintained higher temperatures and moisture levels compared to viscose mulches. Soil organic carbon content varied with fibre type and was higher under jute and hemp mulches. K2O content was significantly higher in soils covered by mulches. All mulches effectively suppressed weeds. The experiment results showed that the newly produced nonwoven mulches could replace the conventional agro foil. Results also suggest that choosing biodegradable nonwoven mulches produced from fibres obtained from natural and renewable sources can influence soil fertility and the availability of nutrients, ultimately affecting plant growth and agricultural productivity.