Viscose Research Articles

Numerical Study of the Optimum Fiber Content of Sealing Grease Using Discrete Element Method.

A sealing grease plays a crucial role in the sealing of shield tails. Its pumpability and pressure sealing resistant sealing performance are greatly affected by the fiber content. In this study, discrete element method models were used to simulate the pressure-resistant tests of sealing grease in order to investigate the influence of viscosity grade and fiber’s aspect ratio on the optimum fiber content of sealing grease. Meanwhile, the rationality of the optimum fiber number determined based on the sealing performance was verified with the unbalanced force and fiber area proportion obtained in the simulation, of which the variation curves with the increasing fiber number were practically identical. The simulation results elucidated that the viscosity of grease had little effect on the optimum fiber content for sealing grease. However, the increase in viscosity can improve the sealing effect, and increasing the fiber’s aspect ratio can reduce the fiber number to reach a specific seal state. Based on the analysis of the total number of fiber spheres for the models with different fiber’s respect ratios, it can be concluded that the sealing grease sample made of the same fiber material and quality can reach the same seal state and seal effect, independent on fiber’s aspect ratio.

Functional Finishing of Viscose Fiber

Functional Finishing of Viscose Fiber

Process of Incorporation of Cerium Oxide in Viscose to Spin Infrared Reflecting Viscose Fibers

The concept of leveraging the optical properties of cerium oxide into viscose fibers was demonstrated in this study. The process of dispersing cerium oxide particles uniformly into viscose dope prior to viscose fiber spinning was studied in detail. Cerium oxide powder was dispersed in the chosen media using mechanical treatments such as ball milling and ultrasonication. These experiments were carried out at two extreme pH values to replicate the viscose spinning bath (acidic pH 5) and viscose dope (alkaline pH 13). The dispersion was characterized for particle size and surface charge properties. A combination of the mechanical treatments synergistically reduced the cerium oxide particle size in acidic and alkaline pH from 1300 to 290 nm and from 1040 to 280 nm, respectively. Three surfactants of different ionic natures were evaluated for stabilizing the cerium oxide dispersions. The effects on the particle size of cerium oxide in two dispersion environments, that is, aqueous and polymeric media, were studied through conventional as well as novel visual characterization techniques. The phosphate ether-based anionic surfactant was found to significantly reduce the dispersed particle size and effectively stabilize the dispersion better, which was validated through a pressure buildup monitoring system during viscose fiber spinning. The surfactant-stabilized cerium oxide dispersion was used to get functional infrared reflecting viscose fibers. To characterize this effect, a direct visual evaluation was done through an infrared camera which indicated a significant improvement of infrared reflectivity and a 2.5–3°C surface temperature buildup of the cerium-oxide viscose fibers in comparison to regular viscose fibers. The infrared reflective property of cerium oxide imparts a thermal insulation effect which was found to increase to a thermal insulating value of 90 in the case of cerium oxide viscose fibers compared with a thermal insulating value of 79 in regular viscose fibers, as measured by the KESF Thermolabo II instrument. This study can very well be extended to many fiber-making processes where an understanding of interfacial interactions of additives with cellulose is critical to impart functionality to viscose fibers.

Exclusive formation of poly(lactide) stereocomplexes with enhanced melt stability via regenerated cellulose assisted Pickering emulsion approach

Stereocomplexation of enantiomeric poly(L-lactide)/poly(D-lactide) (PLLA/PDLA) endows the Polylactide (PLA) with outstanding heat resistance and durability. However, PLA with exclusive stereo-complexation (sc-PLA) is difficult to achieve. Both stereo-complexation PLA and homo-crystallization PLA (hc-PLA) often formed together when PLLA and PDLA blended. In this research, a new strategy was proposed to prepare the PLA with exclusive stereo-complexation (without homo-crystallization) by Pickering emulsion approach, where regenerated cellulose (RC) was used to stabilize the PLLA/PDLA blends and form RC/sc-PLA microsphere. The DSC result shows that the PLA composites prepared in this method presents single melt peak around 220 °C, which is the characteristics of sc-PLA. Most important, this 0.5%RC/sc-PLA possesses excellent melt stability. It does not divide into stereo-complexation and homo-crystallization during the 3 heating cycles. The results indicate that Pickering emulsion approach firstly provide the limited space to limit the diffusion of macromolecular chains and fully combine PLLA and PDLA chains and form complete RC/sc-PLA microspheres. Then the microspheres were hot pressed into films and homogeneous distribution of RC as heterogeneous nucleation agent provides nucleation sites. The intermolecular hydrogen bonding between RC and PLA improves crystallization property and stabilizes the stereo-complexation. This study provides a strategy to prepare the PLA materials with exclusive stereo-complexed crystal and excellent melt stability, which determines the heat resistance and repeated processing.

Flammability and Thermoregulation Properties of Knitted Fabrics as a Potential Candidate for Protective Undergarments.

The most important functional purpose of knitted fabrics used for the protective non-flammable underwear worn in contact with the skin is to ensure wearing comfort by creating and maintaining a constant and pleasant microclimate at the skin surface independently from the environmental conditions. Protective non-flammable underwear may be used by firefighters or sportsmen, e.g., racing (Formula) sportsmen, where a risk of burn injuries (when the car is on fire after a car crash) is present. In order to investigate the flammability and thermal comfort properties of two-layer knitted fabrics, two groups of aramids and flame-retardant (FR) viscose fiber fabrics of different combined patterns and surface structures (porosity and flatness) were designed and manufactured for this research. Aramid fiber spun yarns (METAFINE.X.95®) formed the inner layer (contacting with human skin) of fabrics and aramid/viscose FR fiber spun yarns (METALEN®) formed the outer layer. For the evaluation of the functional characteristics of the manufactured fabrics, the flammability and thermoregulating properties, such as liquid moisture management, water vapor and air permeability, and thermal resistance were investigated. The results show that all tested fabrics are non-flammable, breathable, permeable to air, and can be assigned to moisture management fabrics. Their obtained overall moisture management capacity (OMMC) values are in the range 0.59–0.88. The knitted fabrics with an embossed porous surface to skin had a higher OMMC (0.75–0.88). The thermoregulation comfort properties were mostly influenced by the structure of the fabrics, while the burning behavior was found to be independent from the structure, and the non-flammability properties were imparted by the fiber content of the knits.

Research on the degradation behaviors of wood pulp cellulose in ionic liquids

Utilizing phosphate-based ionic liquids (ILs) solvents for dissolving cellulose to prepare cellulose fibers has attracted much attention for its convenience, high yield, stability and sustainability. However, the degradation behavior during dissolving of cellulose in ILs, which is an important factor for fabricating cellulose fiber, is still unclear. In this work, the degradation of wood pulped cellulose (WPC) in three kinds of phosphate-based ILs: 1-ethyl-3-methylimidazolium dimethyl phosphate ([Emim]DMP), 1-ethyl-3-methylimidazolium diethyl phosphate ([Emim]DEP) and 1-butyl-3-ethylimidazolium diethyl phosphate ([Beim]DEP), were systematically investigated at different dissolution temperatures and dissolution times. The results indicated that the degradation degree of WPC in three ILs follows the order of [Emim]DEP > [Beim]DEP > [Emim]DMP, which is consistent with interaction results obtained by quantum chemical calculation, and degradation degree increases follows the rising of dissolution temperature and the accumulation of dissolution time. Moreover, no reducing sugar (RS) was found in any recycled ILs even when the degree of polymerization (DP) of regenerated cellulose (RC) decreased by 30.4%. In addition, according to the Fourier transform infrared and X-ray diffraction data, the results further proved that the crystallization type of RC changed from type Ⅰ to type Ⅱ. Here, preferable dissolving parameters and experiments data of multiple conditions are provided, which may provide practical reference and guidance for both scientific research and industrial.

Development of Antimicrobial Wound Dressing Bandage using Chromolaena Odorata Leaf Extract

A bandage is a standard of biomaterial used on wounds to protect from infections and to cure wounds. The adhesive bandage also known as sticking plaster protects the wound from friction, bacteria, damage, and dirt. In this study, the leaf extracts of plant (Chromolaena odorata) coated on textiles are being used as a potential drug to promote wound healing. The phytochemical screening and antimicrobial activities of the ethanolic plant leaf extracts was carried out. The leaf extracts were coated on non-woven viscose rayon fabric using Pad-dry cure method. The physical and biological parameters of the coated fabric were analyzed to determine the process of wound healing. The parameters of pH and absorbency were evaluated using the standard protocols obtained from medical textiles. The antimicrobial efficiency (standard protocol AATCC 100), cytotoxicity (MTT assay) and in vitro scratch wound assay using cell lines was studied. The results showed that developed herbal coated bio-bandage featured all the characteristics for ideal dressing. Therefore, it can be promoted as novel bio-bandage for the healing of wounds.

A Study of the Mechanism and Separation of Structurally Similar Phenolic Acids by Commercial Polymeric Ultrafiltration Membranes.

This study examined the behavior and penetration mechanisms of typical phenolic (benzoic) acids, which determine their observed penetration rates during membrane separation, focusing on the influence of electrostatic and hydrophobic solute/membrane interactions. To understand the effects of hydrophobicity and electrostatic interaction on membrane filtration, the observed penetration of five structurally similar phenolic acids was compared with regenerated cellulose (RC) and polyamide (PA) membranes at different solute concentrations and solution pHs. Variation partitioning analysis (VPA) was performed to calculate the relative contributions of electrostatic and hydrophobic effects. The penetration of phenolic acids was mainly influenced by the electrostatic interaction, with salicylic acid having the highest penetration. Penetration of phenolic acids through the PA membrane decreased from 98% at pH 3.0 to 30–50% at pH 7.4, indicating the dominance of the electrostatic interaction. Moreover, based on its hydrophobicity and greater surface charge, the PA membrane could separate binary mixtures of protocatechuic/salicylic acid and 4-hydroxybenzoic/salicylic acid at pH 9.0, with separation factors of 1.81 and 1.78, respectively. These results provide a greater understanding of solute/membrane interactions and their effect on the penetration of phenolic acids through polymeric ultrafiltration membranes.

Synergistic flame retardant weft-knitted alginate/viscose fabrics with MXene coating for multifunctional wearable heaters

Flexible wearable heaters have received increasing attention in energy-saving, diverse personal thermal requirements, and healthcare management. Herein, considering the fire safety application of wearable heaters, the biodegradable alginate fibers and flame retardant (FR) viscose fibers are attempted to mix and weft-knit into the fabric, which interestingly exhibits synergetic flame retardancy with low afterflame time, afterglow time, and peak heat release rate. Further, assisted by the highly conductive Ti3C2Tx (MXene) nanosheets on the surface of the fabric and the periodic nested loops of the knitted fabric, the integrated fabrics possess excellent electrical performance (2Ω sq−1) with the MXene content of 9.13 wt%, electromagnetic interference (EMI) shielding efficiency of 55 dB in the X band, preferable Joule heating performance under safe low voltage (123 °C at 3.5 V) and sunlight/far-infrared heating performance. The superior flame retardancy and multifunctional properties arose from the high-temperature induced well-constructed char layer, unique functionality of interconnected MXene network and multiple scattering of light or wave. Combined with the superior flame retardancy and multifunctional properties, the weft-knitted alginate/FR viscose fabrics with MXene coating become the ideal candidate materials in the fields of wearable heaters with high safety.

Study on the Structure and Skin Moisturizing Properties of Hyaluronic Acid Viscose Fiber Seamless Knitted Fabric for Autumn and Winter.

In autumn and winter, the climate is dry and human skin tends to become dry as a result. The application of hyaluronic acid to a fabric has a certain moisturizing effect, which can further improve the wearing comfort of the fabric. In this study, three knitted fabric structures including weft plain stitch, 1 + 1 mock rib, and 1 + 3 mock rib were designed. The face yarn adopted hyaluronic acid viscose fiber, graphene viscose fiber, nylon, and viscose with different interweaving ratios, and the inner yarn adopted nylon/spandex-coated wire. A total of 18 sample knitted fabrics were woven according to the experimental method of the full test. The effects of the fabric structure and fabric raw materials on skin moisturizing properties were studied and analyzed by testing the skin water content and trans-epidermal water loss before and after coating the fabric on the human skin. The results show that the most significant factor affecting the skin moisture content is the raw material used in the fabric. When the interweaving ratio of hyaluronic acid viscose fiber in the fabric decreases, the moisturizing performance of the fabric on human skin is weakened. The second is the fabric structure. In terms of structure, 1 + 1 mock rib fabric has better moisturizing performance for human skin. When the material adopts hyaluronic acid viscose fiber/graphene viscose fiber (100:0) and the structure adopts 1 + 1 mock rib, the moisturizing effect on human skin is better.

Dual-recognition membrane Adsorbers combining hydrophobic charge-induction chromatography with surface imprinting via multicomponent reaction

The combination of mixed-mode chromatography (MMC) and molecular imprinting technology (MIT) has been proven to be successful for protein separation, but suffered from cumbersome material preparation and limited performance. In this work, a new modification method marrying atom transfer radical polymerization (ATRP) and multicomponent reaction was proposed to simplify the preparation process. Using regenerated cellulose (RC) membrane as the substrate, immunoglobulin G (IgG) as the template protein and tryptamine as the ligand, a dual-recognition membrane adsorbers (MIM) was prepared by mild Ugi four-component reaction (Ugi-4CR) and surface initiated ATRP. Control the ATRP time is the key for surface imprinting. The static IgG uptake and selectivity of UGI membrane were 45 mg/mL and 1.8, respectively, while those of MIM-0.5 were 42.5 mg/mL and 14, indicating that the introduction of molecular imprinting technology significantly improved the selectivity of the membrane to IgG. The MIM-0.5 membrane retains the pH-dependent and salt-tolerant of HCIC. The dynamic flow-through results showed that the MIM-0.5 membrane could effectively separate IgG from IgG/BSA mixed solution with the purity of 88% and retained its bioactivity. This work demonstrated the feasibility of bonding HCIC and MIT to the membrane surface by Ugi-4CR and ATRP.

Viscose-Derived Activated Carbons Fibers as Highly Efficient Adsorbents for Dimethoate Removal from Water.

Extensive use of pesticides resulting in their accumulation in the environment presents a hazard for their non-target species, including humans. Hence, efficient remediation strategies are needed, and, in this sense, adsorption is seen as the most straightforward approach. We have studied activated carbon fibers (ACFs) derived from viscose fibers impregnated with diammonium hydrogen phosphate (DAHP). By changing the amount of DAHP in the impregnation step, the chemical composition and textural properties of ACFs are effectively tuned, affecting their performance for dimethoate removal from water. The prepared ACFs effectively reduced the toxicity of treated water samples, both deionized water solutions and spiked tap water samples, under batch conditions and in dynamic filtration experiments. Using the results of physicochemical characterization and dimethoate adsorption measurements, multiple linear regression models were made to reliably predict performance towards dimethoate removal from water. These models can be used to quickly screen among larger sets of possible adsorbents and guide the development of novel, highly efficient adsorbents for dimethoate removal from water.

Comparative Behavior of Viscose-Based Supercapacitor Electrodes Activated by KOH, H2O, and CO2.

Activated carbons derived from viscose fibers were prepared using potassium hydroxide, carbon dioxide, or water vapor as activation agents. The produced activated carbon fibers were analyzed via scanning electron microscopy and energy dispersive X-ray spectroscopy, and their porosity (specific surface area, total pore volume, and pore size distribution) was calculated employing physisorption experiments. Activated carbon fibers with a specific surface area of more than 2500 m2 g−1 were obtained by each of the three methods. Afterwards, the suitability of these materials as electrodes for electrochemical double-layer capacitors (supercapacitors) was investigated using cyclic voltammetry, galvanostatic measurements, and electrochemical impedance spectroscopy. By combining CO2 and H2O activation, activated carbon fibers of high purity and excellent electrochemical performance could be obtained. A specific capacitance per electrode of up to 180 F g−1 was found. In addition, an energy density per double-layer capacitor of 42 W h kg−1 was achieved. These results demonstrate the outstanding electrochemical properties of viscose-based activated carbon fibers for use as electrode materials in energy storage devices such as supercapacitors.

Thermally conductive poly(lactic acid)/boron nitride composites via regenerated cellulose assisted Pickering emulsion approach

Polymer-based thermally conductive composites have attracted tremendous interest in thermal management of electronics. However, it remains challenging to achieve high thermal conductivity partly because the difficulty to obtain favorable distribution and orientation of conductive fillers within the polymer matrix. Herein, networked boron nitride (BN) conductive pathway was realized within the poly (lactic acid) (PLA) matrix, via regenerated cellulose (RC)-assisted assembly of BN on Pickering emulsion interface based on the noncovalent interaction, followed by solvent evaporation and hot-compressing. The strong noncovalent interactions between BN and RC were found critical to enhance the wettability and stability of BN in aqueous media with a lowest mass ratio of 1:40 of RC and BN. The obtained PLA/BN composites feature a thermal conductivity of 1.06 W/(m K) at 28.4 wt% BN loading, representing an enhancement of 430% comparing to neat PLA, and the crystallinity of the composites could increase significantly from 11.7% (neat PLA) to 43.7%. This simple, environmentally friendly and effective strategy could be easily extended for effective construction of thermally conductive composites.

Tough and electrically conductive Ti3C2T MXene–based core–shell fibers for high–performance electromagnetic interference shielding and heating application

Although transition metal carbide (MXene) fibers are highly electrically conductive, the poor spinnability of neat MXene dispersion and the brittleness of the conductive fibers limit their applications. Herein, a coaxial wet spinning assembly strategy is adopted to fabricate mechanically strong and electrically conductive Ti3C2Tx MXene-based core–shell fibers with regenerated cellulose (RC) as the tough component and graphene oxide/MXene (GM) as the conductive components. By an optimal structure design, the hollow [email protected]90 fiber with the RC shell exhibits an increased strength of 134.7 MPa, a high toughness of 14.1 MJ m−3, a large elongation at break of 13%, and a high conductivity of 2.37×103 S m−1. By sewing on a textile substrate, the hollow [email protected] fibers with a high conductivity of 3.68×104 S m−1 provide an extraordinary electromagnetic interference shielding efficiency of over 90 dB and outstanding solar-thermal energy conversion performances. Similarly, by improving spinnability of the MXene spinning dope with an aqueous dispersion of GO, solid core–shell [email protected] fibers with conductive GM shells are fabricated by the coaxial spinning, and the chemically reduced [email protected] fibers exhibit a high conductivity of 9.90×104 S m−1 and excellent electro-thermal energy conversion performances.

Towards “Business Accountability” Framework: A Comparative Case Study of Global Viscose Fiber Manufacturers

Corporate social responsibility (CSR) is largely on a volunteer basis and sometimes compulsive, irrespective of the tangible social cost. The present study attempts to explore a corporate social accountability model where environment and cost to society (after adjusting the volunteer/stipulated mitigation measures by the industry and capturing the just expectations of the stakeholders) are balanced by the push and pull forces like a lever. The study has significance in making shareholders, partners, and stakeholders more satisfied than the traditional approach of corporate responsibility. The study explores that the social costs of industrial activities may be much more than what is being charged through mandatory commitment on ethical terms. A policy delineating the lines of ethical commitment and commitment originating from compliance may be more effective and can promote competitiveness among the corporations to minimize social costs without compromising cleaner production and industrial efficiency.

Acrylonitrile-butadiene-styrene-based composites derived from “fish-net”-inspired Pickering emulsion for high-performance electromagnetic interference shielding and thermal management

Conductive polymer composites (CPCs) are highly desirable to address the electromagnetic radiation and heat accumulation issue associated with highly integrated electronics. Herein, we report an effective and adaptive strategy to construct a conductive pathway within the acrylonitrile-butadiene-styrene (ABS) matrix using Pickering emulsion as a designer platform. The non-covalently driven “fish-net” assembly of regenerated cellulose (RC) and graphene nanoplatelets (GNPs)/carbon nanotubes (CNTs) at the emulsion interface results in a continuous three-dimensional (3D) conductive network. As expected, the resultant composites exhibit high electrical conductivity of 261.1 S/m, excellent EMI SE of 73.5 dB and thermal conductivity of 4.17 W/mK at 27.8 wt% GNPs and 3 wt% CNTs loadings. Therefore, the Pickering emulsion interfacial assembly strategy exhibits great potential in fabricating high-performance dually-conductive EMI shielding materials.

Investigation on the reaction kinetics, thermodynamics and synergistic effects in co-pyrolysis of polyester and viscose fibers

Investigation on the reaction kinetics, thermodynamics and synergistic effects in co-pyrolysis of polyester and viscose fibers

Optical and Physicochemical Characterizations of a Cellulosic/CdSe-QDs@S-DAB5 Film.

CdSe quantum dots nanoparticles were coated with the thiolated (DiAminoButane based dendrimer) DAB dendrimer of fifth generation (S-DAB5) and embedded in a highly hydrophilic regenerated cellulose (RC) film by simple dip-coating method (immersion in QD-dendrimer aqueous solution) as a way to get a flexible nano-engineered film (RC-4/CdSe-QDs@S-DAB5) with high transparency and photoluminescence properties for different applications. Optical changes in the RC film associated with QDs inclusion were determined by spectroscopic ellipsometry (SE) measurements, which provide information on changes caused in the refraction index and the extinction coefficients of the film, as well as by light transmittance/reflectance curves and photoluminescence (PL) spectra. Impedance spectroscopy (IS) and other typical physicochemical techniques for material characterization (TEM, SEM and XPS) have also been used in order to have more complete information on film characteristics. A comparison of RC-4/CdSe-QDs@S-DAB5 film optical characteristics with those exhibited by other RC-modified films depending on the type of dendrimer was also carried out.

Multifunctional sodium Alginate@ urushiol fiber with targeted Antibacterial, acid corrosion resistance and flame retardant properties for personal protection based on wet spinning

The protective clothing may face acid, high temperature, and bacterial attack in the process of use, affecting its protection efficiency, and multifunctional protective clothing that can meet a variety of needs appear more potential applications. However, multifunctional personal protection clothing has remained an unmet challenge. Here we report a new type of multifunctional clothing via a simple, environmentally friendly wet spinning method to load the urushiol with acid corrosion and antibacterial functions on sodium alginate fiber. This structure uniformly disperses a certain content of urushiol in sodium alginate solution, allowing alginate fibers to have flame retardant properties while having high acid resistance and excellent targeted antibacterial properties. Compared to alginate fibers, the fabricated fibers were treated with different concentrations of sulfuric acid, although the strength was reduced to a certain extent, the fibers retained their original shape and were not dissolved. The thermal analysis showed the fiber also has good flame retardant better than viscose fiber. In addition, the fabricated fiber has targeted antibacterial properties, with an efficiency of 99.99% against Staphylococcus aureus (S. aureus) and bacteriostatic effect on Escherichia coli (E. coli), and good biocompatibility under low concentration conditions. Our work may provide new insights for the development of “green” multifunctional protective clothing. It also provides a research possibility for absorbable surgical sutures.