大容量粘胶长丝连续纺丝机的特点与发展趋势

介绍了粘胶长丝连续纺丝机的现状,并以KR/HD340型大容量粘胶长丝连续纺丝机为例,对该机型的结构、技术特点和发展趋势进行了分析。指出实现自动换筒、提高纺丝速度和降低丝条的沸水收缩率,是粘胶长丝连续纺丝机的发展趋势;国产大容量粘胶长丝连续纺丝机与国外先进的同类装备相比,在性能上还存在一定的差距,需进一步提高国产装备的性能和国内外市场占有率。     

Increasing the dyeing uniformity of viscose textile yarn

Conclusions The possibility of significantly raising the dyeing uniformity of viscose textile yarn by activating the cellulose and by selecting technological spinning parameters which ensure maximum yarn shrinkage before its arrival at the centrifuge has been shown.It has been found that, with increase in the ability of the freshly spun yarn to shrink, its dyeing uniformity is reduced.The dyeing uniformity of viscose yarn prepared by the centrifugal method can be raised by changing its shrinkage on the spinning machine during the spinning process, by activation of the cellulose, and by choosing a precipitation bath which is very suitable for spinning viscose yarns from activated celluloses.Translated from Khimicheskie Volokna, No. 2, pp. 41–42, March–April, 1984.     

Light scattering studies on the ripening of viscose solution

Investigations were made on cellulose xanthate molecular weights by light scattering during the ripening of the solutions of (a) viscose-containing colored thio salts and (b) pure cellulose xanthate separated from viscose. Though an apparent reduction in molecular weight was recorded with time of ripening for the viscose solution, no such fall was observed with pure cellulose xanthate. The apparent fall of molecular weight in the case of viscose has been shown to be due to the increasing absorption of the incident beam and to the change in the value of dn/dc with progressive color formation. Reproducible results can be obtained for cellulose xanthate solutions freed from color. Intrinsic viscosity of the viscoses and the degree of polymerization (D.P.) of the regenerated cellulose from viscoses during ripening were also measured and found to be constant. The results indicate that no degradation of alkali cellulose molecule takes place during the ripening process, irrespective of the state of degradation of alkali cellulose from which the viscose is made.     

Study on the Coagulation Mechanism of Wet-Spinning PAN Fibers

The mechanism of coagulation process of polyarylonitrile (PAN) wet-spinning was studied based on the numerical analysis of the coagulation of viscous polymer solution by diffusional interchange with a bath. Experiments were performed in order to determine the diffusion coefficient of solvent and non-solvent. The numerical solutions of Fick’s second law equations for diffusion were obtained by using the MOL method. The microstructure of nascent fibers is investigated by Transmission Electron Microscope (TEM) and Electron Probe Microanalyser (EPMA). It is found that the speed of outflow solvent is more rapid than that of influent non-solvent. The speed of concentration change of solvent and non-solvent is rapid in outside layers of filament (0.2R) and slow in inner layers. The solvent concentration is keeping a high value at the center of filament. TEM and EPMA show that the microstructure is a typical layered structure. The thickness of dense skin is about 0.2R. The core region of fiber is very loose.     

Polarographic studies of ion binding,II. Zinc-carboxymethylcellulose

The polarographic method of analysis was applied to study zinc ion binding in carboxymethyl cellulose (CMC) solutions. The CMC samples of average degree of substitution 1.14 and 1.35 were selected. The degree of free ions virtually remains constant in wide range of concentrations of CMC solutions and decreases with degree of neutralization. The results are interpreted according to Oosawa's two phase model of polyelectrolytes.     

The influence of the stretch ratio on the rate of diffusion in a wet-spinning process

This article describes diffusion experiments on a single filament spinning set. The aim was to find phenomena which may occur in any wet-spinning process. An alkaline poly(vinyl alcohol) solution containing an indicator was spun out into a coagulation bath containing Na₂SO₄, after which the filament was guided into an acidic second bath. The first bath served to deswell the filament in order to avoid contamination in the diffusion study. In the second bath the diffusion of H⁺ and OH^? ions was studied by measuring the distance which had to be covered by the filament in order to produce a color change of the indicator at the center of the filament. The equation for cylindrical diffusion was tested at various mechanical adjustments of the spinning set. It was found that the rate of diffusion decreases with increasing stretch ratio. Moreover, the relevant diffusion equation is qualitatively very well applicable to the phenomena considered, provided the applied stretch ratio is taken into account.     

X-ray studies of regenerated cellulose fibers wet spun from cotton linter pulp in NaOH/thiourea aqueous solutions

Regenerated cellulose fibers were fabricated by dissolution of cotton linter pulp in NaOH (9.5 wt%) and thiourea (4.5 wt%) aqueous solution followed by wet-spinning and multi-roller drawing. The multi-roller drawing process involved three stages: coagulation (I), coagulation (II) and post-treatment (III). The crystalline structure and morphology of regenerated cellulose fiber was investigated by synchrotron wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) techniques. Results indicated that only the cellulose II crystal structure was found in regenerated cellulose fibers, proving that the cellulose crystals were completely transformed from cellulose I to II structure during spinning from NaOH/thiourea aqueous solution. The crystallinity, orientation and crystal size at each stage were determined from the WAXD analysis. Drawing of cellulose fibers in the coagulation (II) bath (H₂SO₄/H₂O) was found to generate higher orientation and crystallinity than drawing in the post-treatment (III). Although the post-treatment process also increased crystal orientation, it led to a decrease in crystallinity with notable reduction in the anisotropic fraction. Compared with commercial rayon fibers fabricated by the viscose process, the regenerated cellulose fibers exhibited higher crystallinity but lower crystal orientation. SAXS results revealed a clear scattering maximum along the meridian direction in all regenerated cellulose fibers, indicating the formation of lamellar structure during spinning.     

蔗渣浆制造黏液纤维的研究

<正>在黏液纤维制造中,用蔗渣浆代替木浆作原料,常被人怀疑甚至否定其可能性,其主要根据为草类纤维的形态结构不同於木材纤维,而以天然纤维的形态结构作为对原料适合与否的判断标准。我们认为:黏液丝浆的良好制备条件均应最大限度地破坏了天然纤维的形态结构,主要是细胞壁的组织。後者的存在影响丝光化与黄酸化的反应     

Spinning hydrocellulose fibres into zinc-free precipitation baths

Conclusions -- It has been found that the introduction of sodium vinyl sulfonate into the solvent alkali does not exert any important effect on the properties of the viscose, with the exception of stabilizing the cellulose xanthate and retarding its coagulation under the conditions of viscose ripening.-- Sodium vinyl sulfonate added to the dissolving alkali reacts with groups in the cellulose xanthate and to a very slight degree with hydroxyl groups in the cellulose.-- Fibres have been spun from the viscose containing sodium vinyl sulfonate, in the preparation of which it was possible to carry out a higher orientation stretch and to attain better physico-mechanical indices as compared with fibres from viscose containing no sodium vinyl sulfonate.Translated from Khimicheskie Volokna, No. 1, pp. 38–40, January–February, 1991.     

扫描电镜和能谱仪联用检测黏胶长丝污染丝

以黏胶长丝中出现的黑点丝和锈点丝作为研究对象,用扫描电镜和能谱仪联用对其进行表面形貌、截面结构观察及元素分析。结果表明:出现黑点丝和锈点丝的丝条结构没有变化,但是表面有明显杂质,分析杂质成分主要是铁锈、机械油、碳素笔笔油及灰尘等物质。从截面观察可见污染丝与正常黏胶长丝截面无明显差别,均光滑平整,无折点,说明丝的表面受到污染,但其内部结构并未发生变化。     

Production of high-strength cellulose-hydrate fibres

Conclusions The physicomechanical properties of a fibre, particularly its strength, are governed by its structure and by the orientation of the structural elements. Structure formation in precipitation of xanthate from viscose occurs in accordance with the general kinetic laws of phase transitions (formation of supersaturated solutions, formation of centres of the new phase, growth of particles of the new phase according to a linear law (if the substance is in excess) or according to a quadratic law (in the case of diffusion limitation around the centres), formation of oriented structures, and an extremal dependence of the process rate on the temperature).Increase of the zinc sulphate concentration in the coagulation bath leads to an increase in the number of structure-formation centres. The fibre formed possesses a fine fibrillar structure and good mechanical properties. The capacity of this fibre for orientation stretching depends on the structure of the freshly-formed fibre, the degree of plasticisation, and the temperature of the plasticising medium. In ordinary conditions, viscose fibre is stretched by elastic forced deformation. The authors show that in principle it is possible for freshly-formed fibre to be stretched by plastic flow at 165–170°C in an atmosphere of saturated vapor.All-Union Scientific-Research Institute for Synthetic Fibres (VNIIV). Translated from Khimicheskie Volokna, No. 4, pp. 40–45, July–August, 1969.     

Sorption and desorption of carbon disulfide by cellulose for viscose manufacture

Conclusions -- 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.-- After high-temperature mercerization, the accessibility of cellulose with respect to carbon disulfide is increased.-- The reverse method of viscose preparation makes it possible to intensify the penetration of carbon disulfide into the cellulose fibres to a considerable extent, particularly into the most inaccessible portions of its structure.Higher Chemical Engineering Institute, Bulgaria. Translated from Khimicheskie Volokna, No. 3, pp. 17–19, May–June, 1992.     

Process of preparing hydrocellulose fibres and films from aqueous solutions of cellulose in zinc chloride

Conclusions The possibility of preparing concentrated solutions of cellulose in zinc chloride and the properties of the concentrated solutions have been investigated.Experimental hydrocellulose fibres and films have been spun on laboratory and experimental units; these had properties close to those of ordinary viscose fibres and films, and excelled them in a number of characteristics (elastic modulus, knot strength).Translated from Khimicheskie Volokna, No. 6, pp. 6–9, November–December, 1988.     

Kinetic aspects of the mechanism of action of modifiers in spinning viscose fibres

Conclusions -- The kinetics of formation and decomposition of the complex compound which consists of the modifier (EOA or PEG-35), zinc ion, and trithiocarbonate, which is observed in spinning viscose fibre has been studied under model conditions.-- The suggestion of a dependence of the efficiency of action of modifiers on the rate of the reactions for formation and decomposition of a complex compound has been given an experimental foundation. The efficiency of action of a modifier has proved to be directly proportional to the rate of the reactions of formation and decomposition of the complex compound.-- The previously drawn conclusion about a maximum effect of modifier action in neutral or weakly acidic medium has been confirmed.Translated from Khimicheskie Volokna, No. 5, pp. 13–15, September–October, 1990.     

Diffusion dynamics of ionic liquids during the coagulation of solution spinning for acrylic fibers

The coagulation dynamics of acrylic polymer (PAN) with 1‐butyl‐3‐methylimidazolium chloride [BMIM]Cl as solvent for PAN and H₂O as nonsolvent was investigated in detail. On the basis of Fick's second law of diffusion, a mass‐transfer model of [BMIM]Cl from concentrated PAN/[BMIM]Cl solution was established as verified with the experimental data. The established model has a good fit with the experimental data and the diffusion coefficient D of [BMIM]Cl was calculated according to the model. The diffusion coefficient D decreased a little when the concentration of solution increased. As increasing the coagulation bath concentration, the diffusion coefficient D initially increased and then decreased, reaching a maximum of 5 wt% in the coagulation bath. The diffusion coefficient D decreased with the coagulation bath temperature. From the diffusion coefficient and the structure of the coagulated filament, it can be concluded that the diffusion rate of [BMIM]Cl from PAN concentrate solutions is relatively slow, which is prospective to prepare uniform‐structure fibers. POLYM. ENG. SCI., 48:184–190, 2008. © 2007 Society of Plastics Engineers     

纤维素氨基甲酸酯溶液的流变性能

研究了纤维素氨基甲酸酯溶液的流变性能,并与粘胶溶液进行了比较。结果表明,纤维素氨基甲酸酯溶液为切力变稀型流体,与粘胶溶液相比,非牛顿指数小,结构粘度指数大,可纺性差;随温度的升高,表观粘度降低．到25℃以后发生凝固,粘度急剧增大;随着纤维素氨基甲酸酯溶液浓度的增加,表观粘度显著上升,曲线呈指数关系,得到了表观粘度与浓度的经验公式。     

Properties and structure of precipitation baths in viscose manufacture

Conclusions To spin viscose fibre, it is necessary to choose such a composition of the precipitation bath solutions that the water structure in them is broken up; that is, in electrolyte concentration they are above the transition region.In a bicomponent bath, that is, in solutions of the H₂SO₄-Na₂SO₄-H₂O system, it is not possible to improve viscose fibre spinning conditions by changing the composition and concentrations of the components (without additions of other ions or large quantities of organic substances).To select the optimum precipitation bath composition and replace scarce zinc, it is recommended to use magnesium sulfate or aluminum sulfate.Translated from Khimicheskie Volokna, No. 4, pp. 10–13, July–August, 1986.     

Crystalline Structure of Microbial Cellulose Compared with Native and Regenerated Cellulose

Microbial cellulose is a chemically pure form of plant cellulose with an ultrafine reticulated structure. In this study, microbial cellulose was biosynthesized in a static condition by acetobacter xylinium (Gluconacetobacter xylinus) of three different mono- and disaccharides, and its crystallinity structure was investigated and compared with each other and also with the crystalline structure of cellulose existing in cotton and ordinary viscose rayon fibers. According to the results, the cellulose production efficiency of monosaccharide (glucose) was higher than that of disaccharides (lactose and sucrose). The crystalline structures of all biosynthesized cellulose were cell I and their dominant allomorphs were I(alpha), contrary to native cellulose, which was I(beta). The crystallinity amount of microbial cellulose was less than 10-15% of cotton and greater than 9% of viscose.     

Effect of coagulation temperature on the properties of poly(acrylonitrile- itaconic acid) fibers in wet spinning

A dimethyl sulfoxide (DMSO)-water system was used as the coagulation bath in the wet-spun process for poly(acrylonitrile-itaconic acid) fibers. The coagulation bath concentration of DMSO was kept constant at 65%, and the jet stretch ratio was 1. The coagulation bath temperature was varied from 40 to 70 °C. The properties of the fibers so obtained were investigated. The diffusion coefficient of solvent was calculated and the concentration profiles of solvent in a moving filament were computed by using a MOL (method of lines) method. The nascent fibers coagulated at 50 °C obtained a circular symmetrical cross section with high density and strength. The diffusion coefficients of solvent (DMSO) increase with the bath temperature increase. Simulation results show that the noncircular cross section form was the response of the rapid diffusion rate and the loose structure in the core of nascent fibers was caused by the overmuch remained solvent.     

Preparation and properties of transparent cellulose hydrogels

Highly transparent cellulose hydrogels with physical crosslinkage were prepared from nonaqueous organic cellulose solutions and viscose by coagulating and regenerating cellulose in an aqueous solution containing a water‐miscible organic solvent. Nonaqueous organic cellulose solutions used were LiCl/dimethylacetamide, paraformaldehyde/dimethyl sulfoxide, and triethylammonium chloride/dimethyl sulfoxide. Preparation conditions and physical properties of the transparent cellulose hydrogels were studied. The transparency of the cellulose hydrogels depended on the composition of the aqueous solution containing the organic solvent. Furthermore, transparent cellulose hydrogels from viscose showed high tensile strength. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3020–3025, 2003