Effect of xylan on viscose properties

Conclusions The effect of xylan on viscose quality has been studied.An adverse effect of both alkali-soluble and alkali-insoluble xylan fractions on viscose quality (turbidity, CS₂ distribution) has been found. This forms a basis for requirements on pentosan content of celluloses.It is suggested that evaluation of viscose fromleafy wood cellulose use the turbidity character istic.Translated from Khimicheskie Volokna, No. 1, pp. 43–44, January–February, 1987.     

Ion exchange properties of zirconium phosphate phosphite with alkaline earth metal ions.

The ion exchange properties of zirconium phosphate phosphite, a layered compound with asymmetrical layers, towards alkaline earth cations were investigated and compared with those of a-zirconium hydrogenphosphate.

It was found that these cations were easily taken up in the phosphate regionsof_ a-Zr(HPO₄)_{0 7}(HPO₃),.O.5H₂O whereas only Ca²⁺ and Sr²⁺ are directly exchanged from a-Zr(HP0₄)₂.H₂O. The ion exchange mechanism involves a single pnase transition and the solubility of the exchanging cations in the already formed phases. A wide solubility range was found for barium exchange. The interlayer distances and water content of the exchanged forms of zirconium phosphate-phosphite and those of the corresponding phases of zirconium phosphate were compared and discussed on the basis of the structural features of the two hosts.

Zirconium phosphate-phosphite has a relatively low ion exchange capacity (2.5 meq/g) compared to that of the zirconium phosphate (6.64 meq/g)but it is a more facile exchanger for large and hydrated cations.     

Effect of urea on the properties of viscose

Conclusions Additions of urea to viscose lead to a small increase in density and ripeness index, and to a decrease in its viscosity.Urea in viscose does not enter into specific interactions with the components of the viscose and is not decomposed.The change in properties of viscose on increasing the urea content is explained principally by an effect of dilution of the polymer solution.The authors express their thanks to V. G. Kulichikhin for help in this work and for participation in discussing the results.Translated from Khimicheski Volokna, No. 1, pp. 24–26, January–February, 1986.     

钒钛基SCR脱硝催化剂碱土金属中毒

分别制备了钒钨体系和钒钼体系的新鲜催化剂,并通过浸渍法、固态扩散法与干混法分别制备了碱土金属中毒的催化剂,比较了中毒方法、碱土金属以及催化助剂种类等因素对催化剂脱硝活性的影响,并利用程序升温脱附（NH₃-TPD）、程序升温还原（H₂-TPR）和X射线光电子能谱分析（XPS）等表征手段进行分析。结果表明,3种中毒方法中,浸渍法碱土金属中毒对催化剂毒害作用最大;Ca对催化剂的毒性大于Mg,且钒钼体系催化剂比钒钨体系催化剂具有更强的抗碱土金属中毒性能。碱土金属的存在会降低催化剂表面的总酸量与酸位点的强度,提高催化剂的还原温度,改变活性组分的价态并降低催化剂上表面活性氧的比例。     

Effect of intensive drying of viscose fibres on their properties

Conclusions Experimental data are given on the effect of moisture evaporation rate in drying viscose yarns on the strength and elongation, sorptive capacity for water vapor from the air, swelling, shrinkage, and wear resistance of yarns.It has been found that, by regulating the drying temperature, it is possible to affect the capillary-porous structure of a yarn to a considerable degree. Raising the temperature and the drying rate leads to an improvement in wear resistance and yarn elasticity. However, due to the decrease in internal surface area, one may expect a decrease in the sorptive capacity of the yarn in dyeing. A decrease in drying temperature helps increase the degree of swelling, and helps improve the absorption of dye by the yarn.Translated from Khimicheskie Volokna, No. 2, pp. 46–47, March–April, 1984.     

Effect of di-substituted oxides of alkaline earth metals on opacified glazes

Translated from Steklo i Keramika, No. 4, pp. 20–22, April, 1992.     

Effect of 1,2-dimethyl-5-vinylpyridinium methylsulfate on properties of viscose

Conclusions Addition of 1,2-dimethyl-5-vinylpyridinium methylsulfate to viscose in an amount of 5–50% based on the weight of -cellulose does not lead to a specific interaction of it with sulfur-containing components of the viscose and does not exert any important effect on the technological properties of the viscose or its ability to form fibres.In the spinning stage, the additive introduced behaves as a modifier which retards neutralization of the fibre being spun.Trasnlated from Khimicheskie Volokna, No. 2, pp. 15–16, March–April, 1989.     

Effect of defects in high-modulus viscose fibres on their physicomechanical properties

Conclusions -- As a result of microscopic investigation of high-modulus viscose fibres, it has been found that the various types of defectiveness in them amounts to 90%.-- Four characteristic groups of fibre defects have been determined: breakdown in morphological structure - 25%; gas-bubble content - 20%; mechanical contaminants from the viscose - 25%; and mechanical contaminants from the precipitation bath - 20%.-- It has been shown that the presence of defects in the fibre reduces its strength characteristics from 7.7 to 33%, depending on the form of defect and increases nonuniformity in these figures.Translated from Khimicheskie Volokna, No. 4, pp. 49–51, July–August, 1991.     

Acceleration of zinc corrosion in alkaline suspensions containing iron oxides or iron hydroxides

Fast zinc dissolution is of industrial interest in recycling galvanised steel scraps. An acceleration of zinc corrosion in alkaline solutions was observed in the presence of various iron oxides or iron hydroxides. This corrosion was investigated by weight loss, measurements of hydrogen evolution and variation of current in a galvanic cell. The mechanism of this fast zinc corrosion was investigated by electrochemical means and by X-ray diffraction and scanning electron microscopy observations of zinc surface after immersion in alkaline suspensions of iron oxides or iron hydroxides. These insoluble iron compounds were involved in a reduction step leading to iron containing microparticles characterised by a low hydrogen overpotential and which acted as cathodic areas in a galvanic corrosion of zinc.     

Effect of the conditions of spinning viscose textile fibres on their properties

Rigorous respect of the standard character and purity of the spinning solution, spinning bath parameters, and orientation draw ratio ensures obtaining a complex fibre homogeneous over the length. By varying the flow rate of viscose from the spinneret and disk rotation, it is possible to vary the fibre tension, strength, elongation, and shrinkage within wide limits and ensure a high capacity for uniform dyeing. The limits of the overall draw ratio of viscose textile fibres of varying assortment without elementary fibre breakage and formation of nap were established. __________ Translated from Khimicheskie Volokna, No. 6, pp. 28–31, November–December, 2005.     

Alkali and earth alkaline metal contents in the aluminium cathode in aluminium electrolysis

The contents of sodium, lithium, calcium and magnesium in aluminium in contact with NaF–AlF₃-based melts in laboratory and in industrial aluminium cells were investigated in the temperature range 950–1030 C. The experimental data were compared with a thermodynamic model. It was found that the addition of alumina or CaF₂ to the NaF–AlF₃ melts has only a minor effect on the equilibrium content of sodium in aluminium. Cathodic polarization enhances the content of sodium in aluminium. However, polarization has a smaller effect on the concentrations of lithium, calcium and magnesium in aluminium in industrial cells.     

First-principles study of phase-transition temperature and optical properties of alkaline earth metal (Be,Mg, Ca,Sr or Ba)-doped VO2

Vanadium dioxide (VO₂) is an attractive material for energy-saving smart windows due to its metal-to-insulator reversible phase transition near ambient temperature, accompanied by large changes in its optical properties. We conducted first-principles calculations to study the phase-transition temperature and optical properties of alkaline earth metal (Be, Mg, Ca, Sr or Ba)-doped VO₂. The results show that the Be atom prefers to locate at the octahedral interstitial site, while Mg, Ca, Sr and Ba atoms prefer to substitute for the V atom in VO₂. Be, Mg, Ca, Sr and Ba doping reduces the phase-transition temperature of VO₂ 0by 51.4, 59.7, 61.5, 58.4 and 58.3?K, respectively, when the doping concentration is set at one atomic percentage. In addition, the introduction of alkaline earth metal scales the band structures of VO₂, which enhances the ability to block the infrared light (in the order of Be > Mg > Ca > Sr > Ba) and promotes the transmission of visible light (in the order of Be > Mg ≈ Ca > Sr > Ba).     

The curing behavior of resol. III. Effect of alkali metal hydroxides and alkaline earth metal hydroxides as catalyst for the cure of resol

The effect of the addition of cure catalysts on the cure acceleration of ammonia free resol was investigated by means of Curelastometer. The resol which was prepared by the reaction between phenol and formaldehyde with molar ratio 1:1.2 in the presence of NaOH (0.02 mol to phenol) was neutralized with HCI. Catalyst selected from LiOH, NaOH, KOH, Mg(OH)₂, Ca(OH)₂, Sr(OH)₂, and Ba(OH)₂ was added to the resol, and curing behavior of the resol was examined. Both alkali metal hydroxides and alkaline earth metal hydroxides accelerate the curing of resol. The cure acceleration effect of barium hydroxide is the largest. In the relation between the kinds of catalysts and the cure acceleration effect, the larger the ion radius of catalyst the faster the cure of resol. Cure speed of the resol containing either sodium hydroxide or barium hydroxide as a curing catalyst increases with an increase in the amount of catalyst. Apparent activation energies of curing behavior of the resols containing the cure catalysts were in the range 17.0–21.3 kcal/mol.     

Effect of the composition of flame retardant systems on the properties of viscose fibres

The possibility of modifying viscose fibre with hybrid systems containing flame retardants was demonstrated. The effect of the flame retardants on the physicomechanical properties of the fibres was determined. Bath compositions and modification parameters that ensure the sorption-diffusion reaction of the flame retardant and fibre and production of material with a high oxygen index (greater than 70%) were developed. Translated from Khimicheskie Volokna, No. 6, pp. 19–21, November–December, 2008.