Scientific Research Institute of Synthetic Fibers

Tver, Russia

Scientific Research Institute of Synthetic Fibers

Tver, Russia
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Vinogradov Y.A.,Scientific Research Institute of Synthetic Fibers
Fibre Chemistry | Year: 2017

The effect of the precipitation-bath concentration on the viscoelastic properties of wet-spun polyacrylonitrile fiber was studied. The polymer system to be deformed was modeled structurally as a network of intermolecular linkages that consisted of viscous and elastic nodes and could be used to explain many physical phenomena occurring during the deformation, in particular, the known phenomenon of forming voids and vacuoles in the spun fiber. It was shown that the jet-fiber during spinning into mild baths transitioned sequentially from the viscoelastic state, initiating a pathway that formed a viscous (Newtonian) state at its end. The effect of the precipitant composition on the structure-fixation length and time for a jet in the viscous and viscoelastic states was examined. © 2017 Springer Science+Business Media New York


Vinogradov Y.A.,Scientific Research Institute of Synthetic Fibers | Kuz'min N.I.,Scientific Research Institute of Synthetic Fibers | Koval' Y.S.,Scientific Research Institute of Synthetic Fibers
Fibre Chemistry | Year: 2017

The rheological characteristics (complex viscosity, equilibrium relaxation time, equilibrium shear modulus) of a viscoelastic spinning solution obtained in a viscometer and under actual fiber-spinning conditions are examined. It is shown that the optimal regimes for spinning stronger fibers could be predicted by using the spinning-solution rheological characteristics and correlation coefficients obtained in a viscometer. © 2017 Springer Science+Business Media New York


Machalaba N.N.,Scientific Research Institute of Synthetic Fibers
Fibre Chemistry | Year: 2011

We have conducted rheological studies of polymer solutions synthesized using solvents having different dielectric constants. We have determined the effect of this characteristic on the rheological properties of the spin dopes. Estimation of the strength indices of aramid fibers obtained from solutions based on solvents with different dielectric constants made it possible to identify the benchmark value for the dielectric constant. © 2011 Springer Science+Business Media, Inc.


Koval' Y.S.,Scientific Research Institute of Synthetic Fibers
Fibre Chemistry | Year: 2011

Systems of differential equations in cartesian and cylindrical coordinates are obtained to describe a flexible filament rotating in a resisting medium. The concept of the unit aerodynamic drag coefficient of the filament is introduced in addition to the assumptions used in previous studies. The systems of differential equations that were obtained are solved in analytical form using the assumptions that were made. A value is found for the new concept of unit aerodynamic drag coefficient, and ways are described to study it and determine its value for different filaments in practical applications. Complete mathematical expressions are obtained to calculate parameters that are of practical importance in the twisting of a filament - its tension, the maximum radius (diameter) of the torsion balloon, and the conditions under which multiple balloons are formed. It is established that the problem of the form and tension of a filament during its twisting cannot be solved in final form without allowance for the resistance of the medium. © 2011 Springer Science+Business Media, Inc.


Vinogradov Y.A.,Scientific Research Institute of Synthetic Fibers
Fibre Chemistry | Year: 2016

Rheological studies of wet-spinning of fibers were carried out. A solution (18%) of acrylonitrile (60%) and vinylchloride (40%, SKhN-60) in DMF was used. The main rheological characteristics of fiber-jet tension were the apparent longitudinal viscosity and the fiber structuring time; the shear characteristics, the complex (Newtonian) viscosity and equilibrium relaxation time. An attempt was made to relate these rheological tensile and shear characteristics to each other. Two methods were used to calculate the longitudinal viscosity. The first used the segment structuring time (length) to calculate the tensile strains and; correspondingly, the longitudinal viscosity. The apparent viscosity was λa = 1.2.105 Pa.s for a spinning solution Newtonian viscosity of 5.15 Pa.s and spinneret extrusion of unity. This was approximately equal to values for spinning solutions that were obtained by other researchers. The second method was used for the first time to determine the longitudinal viscosity. The equilibrium relaxation time was used to calculate tensile strains and; correspondingly, the longitudinal viscosity. The obtained longitudinal viscosity was called the equilibrium value (6.81 Pa.s). Equations determining the length of the structured fiber-jet segment were obtained theoretically and validated in practice. © 2016 Springer Science+Business Media New York


Kuz'min N.I.,Scientific Research Institute of Synthetic Fibers | Makarov A.V.,Scientific Research Institute of Synthetic Fibers | Podol'skaya T.I.,Scientific Research Institute of Synthetic Fibers | Rogova E.A.,Scientific Research Institute of Synthetic Fibers
Fibre Chemistry | Year: 2011

The rheological properties of concentrated solutions of polyacrylonitrile in dimethyl sulfoxide are studied in steady and dynamic regimes of shear flow as a function of the molecular-mass characteristics of the polymer. It is found that as the molecular mass of PAN increases, the elastic component of the solution viscosity increases more rapidly than the viscous component; this is one of the main reasons for the instability of the formation and structural nonuniformity of fibers. © 2011 Springer Science+Business Media, Inc.


Mitchenko Y.I.,Scientific Research Institute of Synthetic Fibers | D'yachkov A.N.,Scientific Research Institute of Synthetic Fibers | Rudneva L.D.,Scientific Research Institute of Synthetic Fibers
Fibre Chemistry | Year: 2011

Aspects of a gel technology for obtaining polyvinyl alcohol fibers from the high-molecular-weight polymer are examined, and studies are made of the rheological and morphological characteristics of fibers formed from solutions of different concentrations. It is shown that the use of a dry-wet forming method instead of the competing methods of thermotropic transformation and wet precipitation makes it possible to obtain fibers having a strength of 2. 2 GPa and an elastic modulus of up to 32 GPa. © 2011 Springer Science+Business Media, Inc.


Volkov V.Z.,Scientific Research Institute of Synthetic Fibers | Neverov A.P.,Scientific Research Institute of Synthetic Fibers | Valetkin Y.V.,Scientific Research Institute of Synthetic Fibers
Fibre Chemistry | Year: 2011

We present comparative results of tests on commercial and experimental platinum/palladium spinnerets in forming polyacrylonitrile filament yarn of 50 tex. The experimental spinnerets were made with holes of high precision diameter (0. 08 ± 0. 001 mm). The spinnerets were characterized by their integrated throughput (the flow-through time for distilled water) while the filament yarns were characterized by their linear density. We demonstrate a correlation between the filament linear density and the flow-through time. In this case, the criteria for uniformity of the filament with respect to linear density (variance, range, mean-square deviation, coefficient of variation) are statistically significantly smaller for the experimental spinnerets than for the commercial spinnerets. © 2011 Springer Science+Business Media, Inc.


Vinogradov Y.A.,Scientific Research Institute of Synthetic Fibers | Neverov A.P.,Scientific Research Institute of Synthetic Fibers
Fibre Chemistry | Year: 2011

Swelling of the jet during the formation of chemical fibers by the wet method is studied. The swelling of a jet is investigated in the shear regime during extrusion of the spinning solution through a capillary with free efflux and with stretching of a freshly formed jet in the spinning bath. It is shown that the magnitude of the swelling is determined by the viscoelastic properties of the polymer system (equilibrium relaxation time and power-law exponent) and by the conditions of extrusion of the polymer system through a capillary. Relations for determining the magnitude of the swelling and the equilibrium relaxation time are presented. © 2011 Springer Science+Business Media, Inc.


Vinogradov Y.A.,Scientific Research Institute of Synthetic Fibers | Neverov A.P.,Scientific Research Institute of Synthetic Fibers
Fibre Chemistry | Year: 2011

The strain properties of polymer systems under shear and tension have been investigated with chemical fibers formed by the wet method. The main methods of expressing the stresses and strains are examined. It is shown that the stretching of freshly prepared fiber during the formation process is related less with the section of steady flow in a capillary and more with the sections of entry and exit from the spinneret (capillary). It is shown that the method of forming chemical fibers can be used to determine the entry and exit end corrections. © 2011 Springer Science+Business Media, Inc.

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