Special features in spinning cuprammonium fibres into aqueous-organic baths

Conclusions A number of aqueous—organic baths which are usable in spinning cuprammonium fibres have been studied.It has been shown that the composition, precipitating power of the precipitation bath, and spinning conditions predetermine the physicomechanical properties of cuprammonium fibres.Translated from Khimicheskie Volokna, No. 5, pp. 18–20, September–October, 1984.     

Some features of spinning viscose fibre and yarns into zinc-free precipitation baths

Conclusions The use of low-acid, bicomponent precipitation baths with additions of urea to the viscose, or also of baths containing such polyvalent metals as aluminum or magnesium, which permits one to obtain a fibre with improved physico-mechanical indices and fatigue properties at the spinning speeds which have been adopted in manufacturing is very promising in spinning viscose fibres and yarns into zinc-free precipitation baths.Replacement of the expensive zinc sulfate by cheaper reagents and the reduction in sulfuric acid consumption upon use of less concentrated precipitation baths permit one to obtain an economical advantage and eliminate the possibility of contaminating the water basin with toxic zinc.Translated from Khimicheskie Volokna, No. 2, pp. 51–53, March–April, 1988.     

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.     

Effect of stretching conditions on the properties of cuprammonium fibres spun into aqueous-organic baths

Conclusions The effects of jet stretch, stretching in air, and stretching in a plasticizing bath medium on the physicomechanical properties of cuprammonium fibres spun into aqueous-organic systems have been investigated.The roles of jet stretch and orientation stretch have been demonstrated, and conditions for carrying out these operations have been refined.Translated from Khimicheskie Volokna, No. 5, pp. 20–22, September–October, 1984.     

Some special features in the precipitation of hydrocellulose from cuprammonium solutions

Conclusions The effect of precipitation baths with varying precipitation power on the composition and swelling of gels precipitated from a cuprammonium cellulose solution has been examined.The degree of decomposition of the cellulose cuprammonium complex in aqueous-organic systems depends but little on the nature of the organic compound, but the degree of swelling of the freshly spun gel in aqueous-organic systems decreases with increase in the proportion of the organic component in the precipitation bath.Translated from Khimicheskie Volokna, No. 3, pp. 37–39, May–June, 1983.     

Interaction of a cuprammonium cellulose solution with aqueous-organic precipitation baths

Conclusions The effect of the composition and properties of aqueous solutions of nonelectrolytes on the thermodynamics of formation of a polymer phase during the process of spinning a cuprammonium fibre by the wet method has been investigated on the basis of contemporary concepts about aqueous solutions of nonelectrolytes.It has been shown that stabilization of the water structure by the nonelectrolyte and increase in H-bonding between the water molecules and the nonelectrolyte aids in the formation of fibres with higher physicomechanical properties.The suggestion has been made that it is possible to predict the composition of the aqueous-organic precipitation bath on the basis of contemporary concepts about the structure of aqueous solutions of nonelectrolytes.Translated from Khimicheskie Volokna, No. 2, pp. 44–46, March–April, 1985.     

Some features of spinning hollow fibres from polycarbonatesiloxane melts

Conclusions The following parameters have been determined as a result of calculations: fibre tension, solidification path length, and the change along the spinning path of the following: stretching stresses, speed, radius, wall thickness, and fibre temperature.It has been shown that, with increase in take-up speed, the length of the section of fibre deformation is reduced, varying practically proportionally to the flow rate of the polymer system.Stability of the process of spinning hollow fibres from polycarbonatesiloxane melts is assured within a narrow range of stretching force.Translated from Khimicheskie Volokna, No. 3, pp. 41–43, May–June, 1989.     

Kinetics of the decomposition of cellulose xanthate in spinning viscose films into sulfuric acid precipitation baths

Conclusions Rate constants for the decomposition reactions of cellulose xanthate have been determined in spinning viscose films into sulfuric acid baths having acid concentrations of 100–1100 g/liter.The data obtained can be used to determine technological parameters in spinning fibres with assigned physico-mechanical characteristics.Translated from Khimicheskie Volokna, No. 5, pp. 37–38, September–October, 1987.     

Special features in spinning viscose fibre and yarns into a precipitation bath containing sulfuric acid and sodium sulfate

Conclusions The possibility of obtaining a viscose fibre with increased strength up to 25–28 cN/tex, and improved fatigue properties, a low-shrinkage fibre, or a fibre with less loss of strength in the wet state has been demonstrated under experimental conditions. The process of preparing a crimped viscose fibre has been checked out under manufacturing conditions.Eliminating zinc sulfate from the technological process and reducing the specific norms for consumption of sulfuric acid (thanks to the use of precipitation baths which are less concentrated in sulfuric acid) and for neutralizing agents affords an opportunity to reduce contamination of wastewater and to obtain ecological and economic benefits.Translated from Khimicheskie Volokna, No. 6, pp. 16–18, November–December, 1986.     

Preparation of polyacrylonitrile fibre by spinning into organic baths

Conclusions -- The spinning of polyacrylonitrile copolymers into organic baths containing dimethyl sulfoxide and isopropyl alcohol has been investigated. It has been found that the optimum DMSO:IPA ratio in the precipitation bath is 60:40% by wt..-- It has been discovered that the strength of the spun yarn is higher the lower the jet stretch.-- The effect of temperature on orientation stretch ratio has been studied. It has been shown that the optimum temperature for heat stretching of PAN yarn lies in the range 155–160°C.-- The dimethyl sulfoxide content of yarn has been determined by technological transitions. In the final yarn it does not exceed 0.3–1.2% by wt.VNIIPV. Translated from Khimicheskie Volokna, No. 3, pp. 15–16, May–June, 1991.     

Spinning hollow fibres from polyacrylonitrile into degassed baths

Conclusions Changes in the properties of water as a result of degassing by heating have been examined.Degassing the water which is used as a precipitant in spinning hollow fibres of PAN permits one to exert a directed action on their properties.Translated from Khimicheskie Volokna, No. 1, pp. 15–17, January–February, 1989.     

Some special features in spinning fibres from solutions of stiff-chain polymers through an air gap

Conclusions -- A comparison of experimental data with existing theoretical analyses of the stretching stability of jets shows that the model of a generalized Maxwellian liquid is applicable to the process of spinning through an air gap of either isotropic solutions of poly-p-phenylene-1,3,4-oxadiazole and also of liquid crystal solutions of poly-p-phenylene terephthalamide; this takes into consideration the highly elastic reaction of the medium during the stretching process and the dependence of the relaxation time of the medium on the rate of deformation.Comparison of experimental results with theoretical predictions.Translated from Khimicheskie Volokna, No. 1, pp. 34–36, January–February, 1991.     

Preferential precipitation of calcium hydroxide on alkali-resistant glass fibres

Carbon discs 12.5 mm diameter were coated with roughly equal areas of Portland cement (PC) and Alkali Resistant Glass (ARG); PC and Blastfurnace slag; PC and Fly Ash (FA): and with combinations of PC, ARG and BFS and PC, ARG and FA. The dry materials were separated by blank strips of carbon. The reaction was started by wetting the dry components with water. The discs were then stored at 100 percent relative humidity until they were examined in the SEM.

Calcium Hydroxide (CH) released into solution by hydration of PC could thus precipitate on ARG or BFS or FA or on the blank areas of carbon.

In all cases CH displayed a remarkable affinity for ARG in distinct preference to BFS and FA which are also known to attract deposits of CH.

Further the morphology of CH deposited on glass suggested that any tendency of the fibre to move relative to the matrix would result in principal compressive stress perpendicular to the fibre axis. This would reduce the longitudinal strength.

Embrittlement of Glass Reinforced Concrete with age is attributed to the affinity of CH with ARG and the morphology of CH precipitate.     

Some special features of spinning of polyethylene gel-fibre

Slow heating of the polymer powder in the solvent with intense stirring in an apparatus with self-cleaning surfaces is required for obtaining a homogeneous solution of ultrahigh-molecular-weight polyethylene (UHMPE). In spinning UHMPE gel-fibre by the dry-wet method, it is necessary to use a liquid with a low surface tension coefficient in the cooling bath. When ultrastrong, high-modulus UHMPE fibre is fabricated by the gel technology method, spinning the gel-fibre from a 3–4% solution of the polymer with a weight-average molecular weight of (6–7) · 10⁶ at 180–190°C is the optimum version.Tver' State University. Translated from Khimicheskie Volokna, No. 2, pp. 18–21, March–April, 1995.