Effect of proton-donors on the structure and properties of polybenzimidazoleterephthalamide fibres

Conclusions -- The effect of proton donors on molecular mobility, structure, and properties of PBITA fibres has been studied.-- It has been shown that protonation of the imidazole rings in PBITA is accompanied by a retardation in local molecular mobility and by changes in structure and properties of fibres, which should be taken into account in the preparation, processing, and use of these fibres.Translated from Khimicheskie Volokna, No. 6, pp. 18–20, November–December, 1990.     

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.     

Activity of water in some aqueous-salt and aoueous-organic solutions

Conclusions Values for the thermodynamic activity of water in aqueous salt solutions corresponding in composition to the polycomponent precipitation baths in the viscose method of preparing fibres, and also in aqueous solutions of N-methylmorpholine-N-oxide and diethylene glycol have been obtained experimentally.It has been shown that the activity of water in aqueous salt solutions changes only slightly on change in composition within ranges which are analogous to the compositions of precipitation baths or with change in temperature up to 60°C. A considerable change in water activity as a function of composition is observed for aqueous-organic solutions.Clear breaks have been discovered on the curves which describe the dependence of the water activity of aqueous-organic solutions on content of the organic component; these have been interpreted as evidence of a considerable change in the structure and properties of the solution at definite concentrations and they deserve attention in choosing a precipitation bath composition.Translated from Khimicheskie Volokna, No. 6, pp. 42–44, November–December, 1988.     

Morphological and structural features of polyacrylonitrile fibres spun by the dry-wet method

Conclusions -- A technological regime for the preparation of polyacrylonitrile fibres from binary and ternary copolymers has been chosen; these differ from known specimens in having a more uniform cross-sectional structure and a smoother elementary filament surface.-- A considerable difference in crystalline structure of fibres from binary and ternary copolymers which have been spun into a dimethyl sulfoxide—water bath has been shown.-- Fibres from the binary or ternary copolymer which have been spun into a precipitation bath having a large dimethyl sulfoxide content in water are characterized by a lower degree of swelling.-- Shrinkage of fibres from the binary copolymer in the temperature range 200–220°C is twice as small as the shrinkage of fibres from the ternary copolymer.Deceased.VNIIPV. Translated from Khimicheskie Volokna, No. 3, pp. 19–22, May–June, 1991.     

Adsorption of resorcinol and catechol on granular activated carbon: Equilibrium and kinetics

Investigations were conducted in the batch mode for studying the adsorption behavior of resorcinol and catechol on granular activated carbon from a basic salt medium (BSM) at pH≈7.1 and temperature≈30 °C. The isotherm data were correlated with six isotherm models, namely Langmuir, Freundlich, Redlich–Peterson, Radke–Prausnitz, Toth, and Fritz–Schlunder’s using a nonlinear regression technique. It is observed that the catechol isotherm data may be represented by Redlich–Peterson, Radke–Prausnitz, Toth, and Fritz–Schlunder models with similar accuracy (max. dev. 12%). And the resorcinol data may be represented by Freundlich, Redlich–Peterson, Radke–Prausnitz, and Fritz–Schlunder models equally well (max. dev. 15%). Freudlich being a simple model is recommended for resorcinol. At the conditions investigated in this study, catechol is adsorbed to a greater extent than resorcinol. This is due to the compound’s solubility and position of the –OH group on the benzene aromatic ring. The kinetics of adsorption have been found to be diffusion controlled and the value of effective particle diffusion coefficients is of the order of 10⁻¹³ m²/s. Three distinct phases of kinetics—rapid, medium, and slow—have been observed. These results should be useful for the design of adsorbers for removing these pollutants.     

Mechanisms of breakdown of the structure of glass cloth during impregnation with polymer binders

The basic sources of worsening of the quality indexes of insulating glass cloth and the requirements for the properties of the cloth and binder during impregnation were determined: short pile, gas inclusions, thermodynamic characteristics of binder and monofilament on the binder—monofilament, binder—air, and air—monofilament interface, internal stresses in the structure of the cloth, weave geometry, and position of monofilaments in the complex fibre.Stekloplastik—Sertifikat Co., Moscow. Translated from Khimicheskie Volokna, No. 3, pp. 43–46, May–June, 1994.     

System for automated design of equipment for the manufacture of nonwoven materials from polymer melts

Conclusions A system for automated design of equipment for the manufacture of filamentary nonwoven materials has been developed — the SNM SAD. The system has been realized on an SM 1420 computer.An interactive regime of the SAD operation is used; and theoretical and empirical mathematical models have been employed for the basic technological processes in the preparation of nonwoven material; imitative modeling and optimization based on mathematical methods of experiment planning have also been used.Translated from Khimicheskie Volokna, No. 4, pp. 10–12, July–August, 1989.     

Thermodynamic activity of some aqueous-organic solutions

Conclusions It has been found that the concentration dependences of the thermodynamic activity of water in aqueous-dimethylacetamide and aqueous-dimethylformamide solutions have breaks in the concentration regions of organic component of 40, 60, and 85% by wt.A comparison of the data obtained with the structure of two types of fibres for which the investigated solutions are used as precipitants indicates a parallel course for the radical changes in structure of mixed solvents of definite compositions and of fibres which are obtained under precipitation conditions.Translated from Khimicheskie Volokna, No. 2, pp. 16–17, March–April, 1990.     

Investigation of the properties of a mixture based on the rigid-chain polyamidobenzimidazole and a flexible-chain thermoplastic polymer in dimethylacetamide by the sedimentation method

Conclusions -- The sedimentation character of PABI-S—thermoplastic polymer mixtures has been studied where these differ in molecular weight and in the thermodynamic stiffness of the chain; studies were in dimethylacetamide containing 3% by wt. lithium chloride.-- The character of the gradient curve shows that the stiff chain PABI-S fills the role of a matrix in change in polydispersity of the mixed system at PABI-S—thermoplastic ratios of 99:1, 95:5; 90:10; or 80:20%.-- The bimodality on the sedimentation curve for a PABI-S—thermoplastic mixture at a weight ratio of 50:50 indicates compositional nonuniformity.Translated from Khimicheskie Volokna, No. 4, pp. 16–17, July–August, 1991.     

Melting of binary mixtures of low-density polyethylene and alkylbenzenes

Regardless of the dependence on the thermal history and structure of the alkylbenzene the melting point of the LDPE—alkylbenzene binary system is a linear function of the composition for a concentration of the lowmolecular-weight component of up to 0.9–0.95 mass fraction. Annealing of LDPE — alkylbenzene binary systems at temperatures below their melting point leads to differentiation of solvents with respect to the level of thermodynamic affinity. The heat of fusion of LDPE crystals is 293±15 J/g.Ivanovo State Academy of Chemical Engineering. Institute of Chemistry of Nonaqueous Solutions, Russian Academy of Sciences. Translated from Khimicheskie Volokna, No. 4, pp. 18–21, July–August, 1996.     

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

Conclusions -- 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.The authors express their thanks to V. I. Klenin for participating in discussion of the results and for valuable remarks.Translated from Khimicheskie Volokna, No. 6, pp. 35–36, November–December, 1990.     

Polarization-optical methods of investigating structure-formation kinetics in polymer systems

Conclusions Contemporary rapid optical methods have been developed for investigating structural transformations in the precipitation of polymers from solutions, structure study and monitoring during thermal and deformational actions on polymer solutions, films, and fibres.Application of these methods makes it possible to determine basic structural parameters — anisotropy, orientation, size and morphology of supermolecular structures; these characterize operational properties of fibres and films.The experimental assemblies devised on the basis of optical methods with photographic or photoelectric recording of the transmitted and scattered light have improved metrological characteristics; they are universal, and are used to monitor fast-occurring processes of structure-formation in spinning fibres and films without interference into the investigated system.Translated from Khimicheskie Volokna, No. 4, pp. 6–10, July–August, 1986.     

Modification of polyacrylonitrile fibres with halogen-containing polymers

Conclusions The physicomechanical and relaxation properties of fibres based on mixtures of polyacrylonitrile with halogen-containing polymers — polyvinyl chloride, chlorinated polyvinyl chloride, and Ftorlon — have been studied.It has been found that on introducing small additions of HCP, the physicomechanical properties of the fibres rise in an extreme fashion.Translated from Khimicheskie Volokna, No. 2, pp. 44–45, March–April, 1984.     

Cuticular hydrocarbons of gregarious and solitary locustsLocusta migratoria cinerascens

The cuticular hydrocarbons ofLocusta migratoria cinerascens—larvae and adults, males and females, gregarious and solitaries—have been investigated by combined gas chromatography-mass spectrometry. The hydrocarbons comprise 52–78% of the cuticular lipids and are divided inton-alkanes (28.7–47.3%), 3-, 4-, and 5-methylalkanes (11.3–15.8%), internally branched monomethylalkanes (13.7–19.9%), and internally branched dimethylalkanes (19.8–35.9%) with seven or nine methylenes between the two branch points. While the sexual dimorphism does not seem to be reflected in the cuticular hydrocarbon composition, clear quantitative variations favoring the longest chain alkanes have been observed between gregarious and solitary locusts, thus revealing a new phase character in these insects.     

Equation of state of the detonation products of RDX

Summary Experimental data and theoretical ideas concerning the detonation adiabat and the thermodynamic properties of real gases have been used to find the equation of state of the detonation products of RDX in the density range 0–2.3 g/cm³. The equation of state relates mainly to the region of thermodynamic parameters corresponding to adiabatic expansion of the explosion mines the pressure at given values of the density and energy in this region correct to 5–10%.Fizika Goreniya i Vzryva, Vol. 2, No. 4, pp. 85–96, 1966     

Effect of plasticized stretch on the properties of carbon black filled halogenated carbo-chain fibres

Conclusions The effect of plasticized stretch on the physicomechanical and electrophysical properties of yarns based on carbon black filled polymers — 42V fluororesin and chlorinated polyvinyl chloride — has been examined.A number of features of these polymers have been discovered, and recommendations are made on choosing an optimum regime of plasticized stretch of carbon black filled yarns.Translated from Khimicheskie Volokna, No. 6, pp. 8–10, November–December, 1983.     

Processes of formation of coagulation structures in vibrocast coarse-grained thixotropic mixtures

Investigations have been carried out on the effects of various process factors on the formation of coagulation structures in vibrocast coarse-grained thixotropic corundum, mullite — corundum — zircon, and chamotte mixtures. The general regularities and mechanisms of formation of coagulation structures in these mixtures have been established. The results obtained have been used in technological developments of the Ukrainian State Research Institute of Refractories.Translated from Ogneupory, No. 5, pp. 2 – 5, May, 1994.     

Origins of cross-sectional heterogeneity in wet-spun fibres

Conclusions 1. Phase changes have been studied in the polymer — solvent — precipitant system.2. It has been shown that, depending on the concentration and type of precipitant, three different methods of separation of polymer from solution are observed. The phenomena can be used to explain the origin of non-uniformity in the cross-section of wet-spun fibres.Leningrad Branch of the All-Union Scientific-Research Institute for Synthetic Fibres (VNIIV). Translated from Khimicheskie Volokna, No. 4, pp. 52–55, July–August, 1969.     

Generic Phenomenological Theory of Vitrification

In the framework of the thermodynamics of irreversible processes and using a graphical approach based on the simple theorems of differential geometry, a generic phenomenological treatment of the glass transition is developed. A thermodynamic derivation of the basic kinetic condition for vitrification—the Frenkel–Kobeko–Reiner equation—is given in a new generalized form. The temperature course of the thermodynamic functions and the kinetic characteristics of vitrifying systems are constructed using one of the general principles of irreversible thermodynamics. The results thus obtained underline the substantial differences and formal similarities between vitrification, considered as a diffuse kinetic transition and thermodynamic phase transformations. A general reconsideration of the axiomatics of the thermodynamics and kinetics and kinetics of glass transition and relaxation is attempted.     

Deformation properties of yarns spun from solutions of cellulose in N-methylmorpholine-N-oxide and selection of spinning conditions

Conclusions The dynamic and kinematic characteristics of yarns spun from solutions of cellulose in N-methylmorpholine-N-oxide have been studied as a function of the composition of the precipitation mixture and the spinning regime selected.It has been shown that in selecting spinning conditions it is necessary to take into account both the kinetics of precipitation and also the character of gel-formation during the precipitation process.Translated from Khimicheskie Volokna, No. 1, pp. 29–30. January–February, 1989.