Viscose Staple Fiber Research Articles

The corrected H/G factors for accurately describing the delignification and depolymerization of industrial hemp stalks

Establishment of precise kinetic models is beneficial for the control of the degree of delignification and carbohydrate degradation in the pulping process. However, most kinetic models judge the degree of delignification and depolymerization only by holding time or fluctuating temperature, ignoring the effects of temperature and heating-up stage. Thus, this study explored in depth the delignification and depolymerization kinetic behaviors of the kraft pulping process of alkali-extracted hemp stalk material (HSM-AE). The chemical composition characteristics of the HSM-AE were firstly studied, followed by the investigation of the HSM-AE kraft pulping under different conditions. The H/G factor of the wood raw material was not suitable to describe the delignification and depolymerization behaviors during HSM-AE kraft pulping and needs to be corrected. Based on the corrected H/G factors, kinetic models of delignification and depolymerization were established. The parameter fitting results showed that the delignification and depolymerization were mainly dominated by sulfide cleavage and alkaline hydrolysis respectively. The activation energies of delignification caused by alkaline- and sulfide- cleavages were 66.8 and 72.7 kJ/mol; and the activation energies of cellulose depolymerization caused by peeling reaction and alkaline hydrolysis were 111.7 and 120.5 kJ/mol, respectively. Compared with eucalyptus kraft pulping, the activation energy ratio of delignification to cellulose depolymerization decreased, indicating that under the same delignification degree, the cellulose in HSM-AE was easier to alkaline degrade. At present, the process described in this experiment was more suitable to prepare dissolving-grade pulp for further production of viscose staple fiber.

Carbon disulphide and hydrogen sulphide emissions from viscose fibre manufacturing industry: A case study in India

CS 2 and H 2 S emissions are the most prominent environmental footprint of viscose fibre manufacturing industry and this necessitates periodical assessment of their emission load from this sector. Emission factors of CS 2 and H 2 S from viscose fibre manufacturing were determined by conducting in-plant emission assessments in three viscose fibre manufacturing plants (one viscose filament yarn and two viscose staple fibre plants) in India. The CS 2 and H 2 S emission factors were estimated to be 284.03 and 20.9 kg MT -1 (i.e. metric ton or tonne) of viscose fibre (viscose filament yarn or VFY) and 99.64 and 33.15 kg MT -1 of viscose fibre (viscose staple fibre or VSF), respectively. Indian and global CS 2 and H 2 S emission estimates from viscose fibre manufacturing sector were prepared by incorporating these newly developed emission factors. Annual emissions from Indian VSF sector in 2020 were estimated to be 78.32 Gg CS 2 and 26.06 Gg H 2 S while from VFY sector, the same were 15.30 Gg and 1.13 Gg. This signifies an upward revision of the 2001 estimate of 26.8 Gg CS 2 emitted from the entire Indian industrial sector, including viscose fibre manufacturing sector. Further, using the newly developed emission factors for VSF and available global viscose fibre production data of 2017, global annual CS 2 and H 2 S emissions were estimated to be 577.9 Gg and 192.3 Gg, respectively, in 2017 that were predominantly contributed by China and India due to their dominant share in global viscose fibre production, followed by Thailand, Indonesia and Austria. • Emission factors of CS 2 and H 2 S from viscose fibre manufacturing are developed. • In 2020, Indian viscose staple fibre sector emitted 78.32 Gg CS 2 & 26.06 Gg H 2 S. • In 2020, Indian viscose fibre yarn sector emitted 15.30 Gg CS 2 & 1.13 Gg H 2 S. • In 2017, Global CS 2 and H 2 S emissions were estimated to be 577.9 Gg and 192.3 Gg. • China (65.74%) & India (11.11%) had maximum share in global CS 2 & H 2 S emissions.

Single fiber swelling behavior for natural and man-made cellulose fibers under alkaline treatment

Swelling behavior of cotton, dissolving wood pulp (DWP), viscose staple fiber, and Tencel staple fiber in varying sodium hydroxide (NaOH) concentration were investigated by means of optical microscopy and were characterized by molecular mass distribution, X-ray diffractometer, and dynamic vapor sorption. The effect of temperature (20–45 °C) and duration (0–120 min) was studied. The results reveal that the swelling ratio of fiber in alkali solution depends on fiber accessibility and NaOH concentration. Viscose staple fiber exhibited the highest swelling ratio and lowest swelling ratio observed for dissolving wood pulp fiber among all the materials. The cotton or DWP fibers provide maximum swelling during alkaline steeping (18wt % lye) at higher temperatures, i.e., 45 °C. As for viscose staple fiber and Tencel staple fiber, using 12 wt% lye concentration and steeping at lower temperatures, i.e., 20 °C maximum swelling behavior.

Research on Hemicellulose Maleate to Disperse Carbon Black Water Slurries and its Application on Dyed Viscose Staple Fiber

Research on Hemicellulose Maleate to Disperse Carbon Black Water Slurries and its Application on Dyed Viscose Staple Fiber

Incorporating polyacrylamide-functionalized graphene nano-additive enables pilot-scale preparation of mechanically reinforced viscose staple fiber

Herein, we communicate an effective method for pilot-scale preparation of graphene reinforced viscose staple fiber. Via an in-situ polymerization approach, the polyacrylamide (PAM) was firstly grafted on the surface of graphene oxide (PAM-GO). It was then reduced by ascorbic acid into the PAM-rGO nanosheets, featuring good dispersibility and compatibility with the viscose matrix. Subsequently, using the viscous process, the viscous/PAM-rGO composite fiber on the pilot scale. When compared to the pure viscous fiber, the tensile strength and Young’'s modulus of the viscose/PAM-rGO composite fiber that loaded with 1.0 wt% PAM-rGO demonstrated a significant by 170% and 314%. Comparing the experimental results and the Halpin-Tsai theoretical simulation indicated that most of the incorporated PAM-rGO nanosheets aligned along the fiber axis direction. It was further evidenced by calculating Herman's orientation factor (f) of the viscous/PAM-rGO fibers. Additionally, strong non-covalent interactions dominated by hydrogen bonding between the cellulose and PAM-rGO were demonstrated by Raman and FTIR analysis. Furthermore, incorporating PAM-rGO into the cellulose matrix has also improved the thermal stability of the composite fiber. Therefore, we assume that this study will open a new pathway for the scale-up preparation of -incorporated multifunctional polymer fibers.

Water footprint assessment of viscose staple fiber garments

Abstract The viscose fiber industry forms a large part of the textile industry and is a typical water consumption and wastewater discharge industry. As a tool to quantify environmental impacts in terms of water resources, the water footprint assessment (WFA) is a control method for the textile and apparel industry to measure water consumption and wastewater discharge. In this study, the water footprints of viscose staple fiber blouses and blended men's suits were comprehensively evaluated based on the ISO 14046 standard and the life cycle assessment (LCA) polygon method. The WFA results from our study indicate that the production stage of viscose staple fiber garments has the most significant water resource environmental load. Specifically, the water footprint related to the production of viscose staple fiber for three types of clothing accounted for more than 50% of the total water footprint, with men's 100% viscose staple fiber suits having the largest impact on water resources and the environment. Furthermore, our results indicate that the water alkaline footprint is primarily influenced by the viscose staple fiber production as well as the dyeing and finishing processes. NaOH and Na2CO3 are the main pollutants that caused the water alkaline footprint. In addition, the water ecotoxicity footprint was the major driving factor of water resource environmental load. Zn2+ is the main pollutant that caused the water ecotoxicity footprint.

Adsorption behavior and mechanism of Au(III) on caffeic acid functionalized viscose staple fibers

A novel fibrous adsorbent (DAVSF-CA) was synthesized via grafting caffeic acid (CA) onto dialdehyde viscose staple fiber (DAVSF), and used to selectively adsorb Au(III) from simulated wastewater. Fourier Transform Infrared (FTIR), X-ray Photoelectron (XPS) and Nuclear Magnetic Resonance (NMR) spectra confirmed that caffeic acid was successfully grafted on DAVSF through condensation reaction. Adsorption experiments revealed that the adsorption of Au(III) on DAVSF-CA was extremely dependent on pH values and temperatures, and the maximum adsorption capacity of 3.71 mmol/g for Au(III) was obtained at pH 3.0 and 333 K according to the Langmuir fitting. High temperature was favorable for Au(III) adsorption because the adsorption of Au(III) on the DAVSF-CA was endothermic. The competitive adsorption demonstrated that DAVSF-CA had a good preference to Au(III) adsorption in the presence of some coexisting pollutants. The adsorption isotherm data of Au(III) were well-described by the Langmuir model, while the kinetic data were fitted well by the Pseudo-second-order equation. The major reaction involving the reduction of Au(III) to Au(0) was identified by XPS and XRD analysis. Namely, Au(III) was first captured on protonated functional groups via electrostatic adsorption, and then reduced to its elemental form and formed the nano-particles on the adsorbent surfaces.

Optimization of Water Network in a Viscose Fiber Plant

In the production process of viscose staple fiber, a large amount of freshwater, steam and desalinated water will be consumed, and a large amount of acidic and alkaline wastewater will be generated, bringing great pressure on water resource and environmental protection. In this paper, the water using system of a viscose staple fiber plant in northwestern China is studied. The key constraints for water using in this system are pH, oxygen demand (COD) and suspended solid (SS). Since pH and COD are non-conserved quantities, their constraints are property-based. So, the optimization of the water network needs to be carried out from both conventional water system integration and property integration. In this paper, the Mathematical Programming method is used to solve the optimization problem. By analyzing the various constraints and taking the corresponding integration methods, the mathematical model is constructed to target the minimum freshwater flowrate, the minimum regenerated water flowrate and relevant parameters. The optimized network can reduce the freshwater consumption 93.1 m³/h and the wastewater discharge 131 m³/h, achieving obvious water-saving and emission reduction effects.

Use of electron beam irradiation for improving reactivity of dissolving pulp in viscose process

Viscose staple fibres are produced by multi-stage chemical intensive unit operations. Low pulp reactivity is the main reason for higher consumption of chemicals, especially CS2 and NaOH. Electron beam irradiation (EBI) is one potential way to reduce chemical consumption by improving the pulp reactivity. In the present study, pulp reactivity improves from 28.73 to 33.87 and 39.85 for pulp irradiated at 2 kGy and 5 kGy, respectively, as compared to non-irradiated pulp. The viscose dope prepared from the irradiated pulp shows improvement in filterability (kw) and ripening index. This indicates improved mass transfer through EBI treatment by providing pulp accessibility towards NaOH and CS2.

Situation in Russian Chemical Fibre Market

In 2014, chemical fibre demand and consumption in Russia stayed practically at the level of the preceding year. Production (capacity utilization factor 59%) and import rose respectively by 1.9 and 3.5%, export declined by 9.1%. Demand and consumption of viscose staple fibres grew respectively by 21.4 and 29.9% and their import, in consequence, shot up by 25.3%. Demand and consumption of polyester (PE) staple fibres increased a little and production, more noticeably (by 11.5%), import fell slightly and export, quite substantially (by 44.2%). Demand and consumption of polyacrylonitrile (PAN) fibres, primarily as tow procured mostly by import, went up by more than 40%. Progress in polypropylene (PP) staple fibre market was marked. Compared to 2013, demand, consumption, production, and import of polyamide (PA) textile yarns improved with forced reduction of their export by 17%. The results with regard to PE textile yarns were negative in 2014 when their demand, consumption, production, import, and export dropped by 16, 17, 40, 12, and 50%, respectively. On the contrary, demand and consumption of PP textile yarns rose steeply (by 68 and 79%, respectively). Rise of all indicators, except import, to the 3-5% level was noted for PA technical and cord yarns. Import of PE technical and cord yarns is continuing unabated. The year under report was a fiasco in the domestic market of PP film yarns that were being actively introduced into the national economy until recently. The problems of chemical fibre development in Russia are being solved for the most part pretentiously without definite involvement of power structures. The strategy until 2030, even in the case of its realization, is characterized by a twofold drop in the output of this product against the pre-restructuring level and continuation of import by no less than 40% of the total volume of their consumption.

Chemical Fibres in Global and Russian Markets in 2012

The global textile fibre market in 2012 reached 85.8 million tons, surpassing the 2011 level by 4.5%. The output of chemical fibres rose by 6% to 56 million tons, including synthetic fibres by 5.6%. Amongst the latter, polyester fibres (PEF) occupy the leading place. Their production in 2012 reached 41.4 million tons, rising above the preceding year by 6.1%, including textile and technical yarns by 9 and 2%, respectively. The output of cellulose fibres grew for the first time by 10.2% to the 5.2 million ton level, including viscose staple fibre by 13%. The global chemical fibre production structure is dominated by PEF (74%), followed by cellulose (9%), polyamide (7%), polypropylene (5%), and polyacrylonitrile (4%). Spandex, aramid, carbon, and others constitute 1%. In regional term, China is the unchallenged ruler – 65% of global chemical fibre production is concentrated in this country, followed far behind by India and the USA (5% each), Taiwan (4%), and South Korea (3%). The remaining countries account for 18%. The situation with chemical fibres in Russia is as gloomy as before. The demand for them exceeds consumption on average by 6% and production by 62% and is made good by import. On the whole, chemical fibre production in the country rose by 2.7% to 140,000 tons, which is extremely low compared to the pre-restructuring time. The demand and import fell relative to 2011 by 3.0 and 3.5%, respectively. The growth of production of acetate tow, PEF staple fibre, spunbond, and a whole range of polypropylene products in this period can be considered positive.

A Study on the Structure and Properties of Pineapple Leaf Viscose Fiber

To develop a new kind of functional textile material, viscose fiber was prepared from natural and antibacterial pineapple leaf fiber and its structures and properties were explored with analyzing methods of sensory evaluation, SEM, FT-IR, TG, DTG and DSC. The results showed that the prepared pineapple leaf viscose fiber was white, shiny, fine, smooth, soft, and somewhat curly with even fineness. Its arrangement was verticall y parallel with some obvious grooves. Irregular zigzaging and the skin-core structure were observed in cross section. The fiber had characteristic groups of cellulose and absorption peaks at 1737.74, 1506.23 and 1431.82 cm-1 almost disappeared, and it showed high purity. The pyrogenation mechanism of pineapple leaf viscose fiber was similar to that of pineapple leaf fiber, but thermal stability of pineapple leaf viscose fiber was slightly lower than that of pineapple leaf fiber. Pineapple leaf viscose fiber belonged to cotton-type viscose staple fiber. The basic properties met the requirements of the first grade of viscose fiber. The mechanical properties reached top standard. It was a good kind of antibacterial textile material with strong bacteriostatic and bactericidal action against Staphylococcus aureus, Escherichia coli and Candida albicans.

Grey-box modelling of a viscose-fibre drying process

A dynamic model of a through-air-drying process for viscose staple fibres is presented in this article. In this process fibres formed to a porous web are transported through a convective dryer that consists of numerous rotating drum sieves. Finally, the fibres pass through two remoistening drums. The structure of the model is modular and scalable. On applying spatial discretization the originally partial differential system equations (conservation of mass and energy) turn into a system of ordinary differential equations. Drying rates and heat transfer rates are calculated using phenomenological equations for heat and mass transfer. Kinetics of drying is separated into three phases, where viscose fibres are hygroscopic. The process model is able to simulate transient behaviour of the dryer like changes of the incoming fibre moisture, changes of the drying air temperature and humidity and changes of the thickness of fibre layer on the drums. Stationary validation of the longitudinal fibre moisture distribution along the dryer shows good accordance with measurement data at different operating points, for example, different temperature profiles. Dynamic data like temperature transients are utilized for both model fitting and validation of the dynamic model. For the remoistening process and disturbance behaviour concerning the thickness of the fibre web, black box models have been identified. Results of a successful application of the model in a predictive control algorithm are shown.

Study on spliced yarns of different spinning technologies. Part I: tensile characteristics

The details of a study on splicing behavior of viscose staple fiber yarns, prepared by ring, rotor, and air-jet spinning technologies, are reported in this paper. All the yarns had six different color tracers with each having 0.3% of total fibers. The mechanical and structural properties of splices were studied. A three-variable three-level factorial design approach proposed by Box and Behnken was used to study the interactive effect of splicing parameters. The splicing parameters such as splicing length, duration of splicing air blast, and splicing air pressure were varied to prepare spliced yarn samples. Splices were introduced at all these levels for the three different technologies. The present paper (Part I) deals with the mechanical characteristics of splice portions, i.e. retained splice strength (RSS) and retained splice elongation (RSE). It has been observed that there are significant effects of all these parameters on the tensile characteristics of spliced yarns. However, the trends are different for different spinning technologies. Part II of this paper deals with the internal structural characteristics of splices.

Study on spliced yarns of different spinning technologies. Part II: structural characteristics

A detailed study on structural parameters of splices of viscose staple fiber yarns made from ring, rotor, and air-jet spinning technologies are reported in this paper. All the yarns each had six different color tracers with 0.3% of total fibers. A three variable three-level factorial design approach proposed by Box and Behnken has been used to study the interactive effect of splicing parameters. The splicing parameters, such as splicing length, duration of splicing air blast, and splicing air pressure were varied to prepared spliced yarn samples. Splices were introduced at all these levels for the three different technologies. This paper deals with the structural characteristics of splice portions, i.e. splice diameter, helix angle, splicing coefficient of fiber (SCF), and fiber overlapping coefficient (FOC). The structural characteristics, such as splice diameter, helix angle, SCF, and FOC, are significantly affected by the different splicing parameters (i.e. splice length, duration of the opening air blast, and splicing air pressure). Different types of yarns (ring-, rotor-, and air-jet-spun) show different trends of structural characteristics with splicing parameters. Part I of this paper deals with the mechanical characteristics of spliced portion.

Study on splicing performance of different types of staple yarns

The present paper reports the detailed study on the splicing behavior of viscose staple fiber yarns made from ring, rotor, friction and air-jet spinning technologies. The linear density of all the yearns was kept constant at 29.5 tex. The splicing parameters like splicing pressure and duration of the splicing were taken as variables. Three levels of splicing pressure at constant splicing duration and three levels of splicing durations at constant splicing pressure were considered. Splices were introduced at all these levels for the four different technologies. These splices were tested for their tensile properties and the properties of splices were evaluated in terms of retained splice strength (RSS) and splice break ratio (SBR). The splice photographs were taken and splices were analyzed for their structure and for diameter profile along the length of the splice.

Drying and conditioning viscose staple fibre

With respect to the mechanism of moisture removal, the process of drying viscose staple fibre is divided into two stages. The first stage takes place at a constant rate. Removal of moisture takes place by the mechanism of evaporation from a free surface. In the second stage, mainly solvated bound water is removed, by a desorption mechanism, which is described by an equation for a first order chemical reaction.

Properties of Viscose Fibres Modified in an As-spun State by Cross-linking

An investigation is reported in which as-spun (just before drying) viscose staple fibres were modified by means of cross-linking with dimethyloldihydroxyethyleneurea (DMDHEU), dodecylbenzolsulphonic acid/MgCl2.6H2O being used as a catalytic system. Their physico-mechanical properties and their most important textile properties are compared with those of conventional (standard) viscose fibres and of polynosic fibres. It is established that, for a range of their properties, the cross-linked fibres are superior to the standard viscose fibres and, in some of these properties, they are close to the polynosic fibres or are even superior to them. Some of the properties of the cross-linked fibres indicate that they can be successfully used in all applications where the fibres must be intensively treated in the wet state or in the presence of strong swelling agents or solvents.

4—THE MECHANICS OF THE BENDING OF NON-WOVEN FABRICS PART IV: PRINT-BONDED FABRIC WITH A PATTERN OF ELLIPTICAL HOLES (KEYBAK)

A study is reported of a commercial print-bonded non-woven fabric (Keybak), made of viscose staple fibres arranged to contain a pattern of elliptical holes and print-bonded by acrylic latex in strips. An analytical model based on the structural features and using a composite-materials approach was employed to interpret the experimental measurements of the bending stiffness of the fabric. The grouping of the fibres in the fabric into straight and severely curved ones permits freedom of relative fibre motion among curved fibres and requires only the straight fibres to resist the bending moment.

Jute-Viscose Blending: Some Optimum Conditions

The practicalities of blending viscose staple fiber with Tossa jute were investigated. A critical tossa jute :viscose blend proportion was found to exist at which yarn tenacity was minimum. For blended yams the optimum twist factor was practically constant at 25.0 (turns per cm × √tex), and irregularity was reduced as rayon proportion increased. Weaving efficiency and fabric quality showed improvements even with 10% viscose in the blend. The used of bleached jute in the blend increased whiteness at the loss of strength.