Viscose Manufacturing Research Articles

Continuous and sustainable cellulose filaments from ionic liquid dissolved paper sludge nanofibres

The textile industry is resource-intensive, which has a significant impact on global emissions and waste pollution. To meet the demand of textiles over a third of fibres used in manufacturing are sourced from fossil fuels. As the global demand for textiles continues to grow, manufacturers are having to seek innovative approaches to providing sustainable and regenerative cellulose fibres. However, the latest climate change pressures on the textile industry have uncovered grave environmental issues associated with traditional regenerative cellulose production, such as the viscose manufacturing process. The viscose process requires intensive use of hazardous chemicals which leads to water pollution and ecotoxicity. In addition, if forestry products are unsustainably sourced for this process, this can lead to resource scarcity and deforestation. To provide a holistic solution for mitigating these challenges this study uses the by-products of paper manufacturing dissolved in an ionic liquid to produce regenerated cellulose filaments. Paper mill sludge (PMS) is a cellulosic by-product typically used on animal bedding and land spreading. The material has been dissolved in an ionic liquid - 1-ethyl-3-methylimidazolium diethyl phosphate - with the aid of a co-solvent dimethyl sulfoxide (DMSO) - and spun into continuous filaments for textile production. The mechanical properties of paper sludge filaments are found to be competitive with commercial viscose, which is promising for their drop-in replacement. It is also demonstrated that by increasing the concentration of the PMS from 9% to 12.4%, an improvement of the filament properties can be achieved; an increase in modulus from ∼19 GPa to ∼26 GPa and strength from ∼223 MPa to ∼282 MPa. These values are shown to be competitive with other commercial, less sustainable, regenerated cellulose fibres.

New sulfur control solution has cut cost and supported environmental compliance in viscose manufacturing

New sulfur control solution has cut cost and supported environmental compliance in viscose manufacturing

An enzyme-catalysed bleaching treatment to meet dissolving pulp characteristics for cellulose derivatives applications

Bleached cellulose with good end-properties (≈ 90% ISO brightness and 62% cellulose preservation) was obtained by using a totally chlorine-free biobleaching process (TCF). Unbleached sulphite cellulose was treated with Trametes villosa laccase in combination with violuric acid. This enzymatic stage (L) was followed by a chelating stage (Q) and then by a hydrogen peroxide stage reinforced with pressurized oxygen (Po), resulting to an overall LQPo sequence. The use of violuric acid was dictated by the results of a preliminary study, where the bleaching efficiency of various natural (syringaldehyde and p-coumaric acid) and synthetic mediators (violuric acid and 1-hydroxybenzotriazole) were assessed. The outstanding results obtained with laccase-violuric acid system fulfil most of the characteristics of commercial dissolving pulp, totally acceptable for viscose manufacturing or CMC derivatives, with the added advantage that the enzymatic treatment saved 2h of reaction time and about 70% of hydrogen peroxide consumption, relative to a conventional sequence (Po).

Properties of cellulose pulps and their influence on the production of a cellulose ether

Abstract Several grades of cellulose pulps were investigated for their influence on the product quality of a cellulose ether, ethyl-hydroxy-ethyl cellulose (EHEC). The selection of the pulps was based on pulping process, original wood type and intrinsic viscosity. In total, five sulfite pulps and four sulfate pulps were chosen, of which all but one sulfate pulp were of dissolving grade. The physical and chemical properties of the pulps were analyzed as well as important qualitative parameters of the final product EHEC. The influence of pulp properties on EHEC quality was investigated by multivariate data analyses. Principal component analysis showed that due to the influence of all variables, the pulps aligned in groups in accordance to the selection criteria pulping process and wood type. Partial least square regression revealed that high gel formation in EHEC is explained by the pulp properties high intrinsic viscosity and high Mw in combination with high caustic absorption rate and high total caustic absorption. The amount of hemicelluloses, in particular xylose, also contributed to gel formation. High cloud point for an EHEC solution was explained by a high MSEO and low DSEt of the EHEC molecules, where in turn a high MSEO could be predicted by a high pore area, high PD and a low caustic absorption rate. A low DSEt could on the other hand be predicted by a low hemicellulose content and hence a high R18. In a separate model, the same pulp properties explaining MSEO and DSEt also predicted cloud point directly. Fock reactivity and viscose dope filterability, both test methods originating from the viscose manufacturing, were shown to predict cloud point but have low predictability on other EHEC quality parameters. The models achieved can thus be utilized to predict final EHEC product qualities for new pulps within the design set of the chosen pulps.

Chemical Pulping: The influence of properties in cellulose pulps on the reactivity in viscose manufacturing

This paper describes properties in cellulose pulps to adress the increased quality demands on pulps for viscose production. Several grades of cellulose pulps were selected to investigate their chem ...

Accessibility, reactivity and supramolecular structure of E. globulus pulps with reduced xylan content

The correlation of structural assembly on a molecular level with macroscale properties such as accessibility and reactivity was investigated. A series of TCF-bleached E. globulus kraft dissolving pulps was prepared aiming at a specification suitable for viscose application. The removal of xylan to a comparable level was achieved by different pre- and post-treatments. Solid-state CP-MAS 13C NMR was used to determine the degree of order and the lateral fibril dimensions of cellulose fibrils. The results of the NMR measurements were related to the processability of these pulps during viscose manufacture, expressed in terms of filterability of the viscose dope and its amount of undissolved particles. The cellulose crystallinity did not affect the pulp reactivity. It was noticed that the cold caustic extracted (CCE) pulps revealed both large fibril aggregate width as determined from NMR data and low reactivity toward xanthation at the same time. These pulps exhibited significantly higher amounts of alkali-resistant xylan than those prepared by prehydrolysis kraft cooking.

Optimization of the Enzymatic Activation of a Dissolving Pulp Before Viscose Manufacture

As a continuation of an earlier enzymatic study on a dissolving pulp before viscose manufacturing, a new set of experiments were carried out with the best-performing enzyme from that study, Carezyme(R). The intention was to optimize the enzyme treatment so that the subsequent viscose process could be carried out with the lowest possible demand for chemicals in the etherification stage. The study focuses on pulp yield, reactivity, viscose viscosity (measured as ball-fall time), and the filter clogging value of the viscose.

TCF bleaching of hardwood pulps obtained in organic acid media: Production of viscose-grade pulps

High-purity, viscose-grade pulps have been produced by means of delignification (in media containing formic or acetic acid) and TCF bleaching (using a E(O)ZP sequence). Aspen or Eucalyptus globuluswood chips were treated in media made up of either acetic acid, water and HCl or formic acid, water and hydrogen peroxide (Acetosolv and Milox technologies). Under selected conditions, unbleached pulps with kappa numbers in the range 14.0–28.5 were obtained at 50.0–53.7% pulp yield. These samples were subjected to E(O)ZP bleaching to reach the viscose-grade target values for chemical and physicochemical properties. Among the pulps tested, the bleached Milox pulp from Eucalyptus wood showed the best properties to be used for viscose manufacture (pentosan content of 1.4%, SCAN viscosity of 598 mL/g, ISO brightness of 89.9% and alkaline resistances of 90.1% and 97.0% in the R-10 and R-18 tests).

Improved sampling and analytical method for airborne carbon disulfide measurement in the workplace

An improved sampling and analytical method for airborne carbon disulfide (CS2) both in the laboratory and in a rayon viscose manufacturing plant is described. A tube-type diffusive sampler (ATD) packed with solid Spherocarb was used for airborne CS2 collection. The ATD was then thermally desorbed and analyzed by (GC-MS). A standard curve range of 0.69 to 103.4 μg was established with correlation coefficient (r)>0.998. Desorption efficiency was 100% mean recovery 97.8% and coefficient of variation 0.97) between the proposed method and the current method for fixed-point samples. The proposed method can provide a specific, sensitive, convenient, and reliable tool for assessment of occupational exposure to CS2. Using this method to assess CS2 exposures gives findings comparable to those of the traditional method with respect to accuracy, precision, and effects of environmental interference.

Electron-processing technology: A promising application for the viscose industry

In marketing its IMPELA ® line of high power, high-throughput industrial accelerators, Atomic Energy of Canada Limited (AECL) is working with viscose (rayon) companies world-wide to integrate electron-processing technology as part of the viscose manufacturing process. The viscose industry converts cellulose wood pulp into products such as staple fiber, filament, cord, film, packaging, and non-edible sausage casings. This multibillion dollar industry is currently suffering from high production costs, and is facing increasingly stringent environmental regulations. The use of electron-treated pulp can significantly lower production costs and can provide equally significant environmental benefits. This paper describes our current understanding of the benefits of using electron-treated pulp in this process, and AECL's efforts in developing this technology.

Cardiovascular disease and occupational exposure to environmental tobacco smoke.

Results of chemical analysis, animal experiments, and human studies are reviewed, criticized, and found not to support claims of an association between workers exposed to environmental tobacco smoke (ETS) and occupational coronary heart disease. This review also recommends refinement of the use of dose surrogates, as presently practiced by the Occupational Safety and Health Administration (OSHA), for regulating indoor emissions from combustion engines, coal furnaces, tobacco leaf processing, rayon viscose manufacturing, and rubber curing. The work standards OSHA uses for regulation of these complex mixtures could also be used in evaluating ETS and relate to the following constituents of ETS: nicotine, carbon monoxide, benzo[a]pyrene, and carbon disulfide. The data indicate that the levels of these substances potentially arising from ETS are many orders of magnitude below their respective PELs. Thus, based on the standards for exposure surrogates for other complex mixtures, the potential worker exposure from ETS does not require further regulation by OSHA, based on cardiovascular disease.

Energy-saving technologies in viscose manufacture

-- Results of the realization of energy-economical technologies in the processes of continuous deaeration and two-stage vacuum crystallization of sodium sulfate from technological solutions in viscose manufacturing have been given.

Sorption and desorption of carbon disulfide by cellulose for viscose manufacture

-- The results of a study of the sorption and desorption of carbon disulfide may be used to characterize the structure of cellulose, particularly its accessibility to reagents during viscose manufacture.

Connection between the supermolecular structure of viscose with characteristics of the cellulose and with the properties of fibres and films obtained

-- The supermolecular structure of spinning solutions from viscose manufacturing operations in the Balakovskii “Khimvolokno” PO has been studied by the turbidity spectrum method.

Photometric determination of aluminum sulfate in a zinc-aluminum-containing bath in viscose manufacturing

A procecure has been developed for the photometric determination of the aluminum sulfate content of a mixed zinc-aluminum-containing precipitation bath in viscose manufacturing, using the bifunctional organic reagent chromazo-BRZ.

The use of electrodialysis to desalinate waste water in low-waste viscose manufacturing technology

The advisability of using electrodialysis to desalinate and concentrate waste water from viscose manufacturing has been shown.

Chemical resistance of glass-filled polypropylene in the aggressive media of viscose manufacturing

The introduction of fiberglass somewhat increases the swelling of polypropylene in acidic media, but due to the preservation of a high level of mechanical properties, it permits one to increase the operational lifetime of parts and to reduce warping.

Construction of a phase diagram for the cellulose xanthate-solvent system

-- A fragment of the phase diagram for the system cellulose xanthate—aqueous alkali solution has been obtained, corresponding to a liquid-phase (amorphous) separation with a lower critical mixing temperature. -- The importance of determining the thermodynamic nature and temperature region for metastability of viscose solutions for optimizing the technological process of viscose manufacturing has been demonstrated.

Clean-up of industrial wastewater from viscose manufacturing on filters having a foamed polystyrene charge

Basic technological parameters of the process of filtering industrial wastewater from viscose manufacturing on filters having a polystyrene charge have been determined.

Technological modeling of clarification of wastewater from viscose manufacturing

The kinetics of precipitation of suspended substances has been determined on real wastewater from viscose manufacturing at definite properties of the suspension.