Structural features and properties of composite and ultrathin fibres from melts of polymer mixtures

Kiev Technological Institute of Ligh Industry. Translated from Khimicheskie Volokna, No. 3, pp. 45–47, May–June, 1992.     

Structural features of fibre-plastics based on profiled fibres

Conclusions The basic structure features of MRFP based on jointly profiled fibres consist of a diversity of cross-sectional fibre forms with predominance of an irregular pentagonal form, and the presence of principally fine pores having a size which is 0.1 to 0.3 times the diameter of the original fibres.The strength of MRFP in extension depends on the cross-sectional form of the profiled fibres and is greater, the less the degree of change in fibre form during profiling.Hygroscopicity and the extent of change in strength on moistening are approximately twice as small in MRFP as they are in the starting fibres.Translated from Khimicheskie Volokna, No. 6, pp. 36–38, November–December, 1986.     

Structural features and strength of carbon fibres

Conclusions -- Dimensions, orientation of the ordered regions, and also the heterogeneous structure parameters have been determined for a number of foreign and domestic high-strength and high-modulus carbon fibres (CF). Characteristic features of the behavior of the heterogeneous structure of CF with change in dimensions of the ordered regions have been noted.-- It has been shown that small dimensions of the ordered and unordered regions are characteristic of high-strength CF together with an increased mean density of the unordered and porous phases.-- An attempt has been made to establish correlations between the ultimate strength of CF in extension and the heterogeneous structure parameters of the fibre.Translated from Khimicheskie Volokna, No. 1, pp. 47–49, January–February, 1991.     

Modified chemisorptive fibres based on a copolymer of acrylonitrile with 5-vinyl-2-methylpyridine

Conclusions Conditions for the preparation of salt forms of a chemisorptive fibre based on a copolymer of acrylonitrile and 5-vinyl-2-methylpyridine have been worked out.It has been found that the formation of stable salt forms of the copolymer is determined by the basicity of the pyridine groups.The effect of the basicity of the functional groups and salt forms of the polymer on the equilibrium and kinetic characteristics of fibres in the sorption of gases of acid or basic character has been shown.Translated from Khimicheskie Volokna, No. 1, pp. 22–24, January–February, 1988.     

The rheological properties of molten mixtures of polyoxymethylene and copolyamide: Their fibrillation and microstructure

The rheological properties of molten mixtures of polyoxymethylene and copolyamide have been investigated by the methods of capillary viscometry over a wide range of shear stresses. It has been found that at relatively close values of the melt viscosity polyoxymethylene (POM) and copolyamide (CPA) form mixtures which differ markedly in viscosity and elastic properties from the original polymers. Depending on the magnitude of the shear stress, the viscosity of mixtures of definite composition may be either higher or lower than the viscosity of the components. Three- to tenfold swelling of the stream emerging from the capillary is observed for such mixtures, whereas at the same temperatures and stresses no swelling of the POM and CPA extrudates is practically observed. The data obtained are accounted for by the fact that the flow of mixtures through the capillary involves the formation of hundreds of thousands of ultrathin fibres of POM in the matrix of CPA, which are oriented along the flow axis.     

Structure and properties of polymer–wood composites based on an aliphatic copolyamide and secondary polyethylenes

Composite materials based on an aliphatic copolyamide and a secondary polyethylene, as thermoplastic matrices, and wood chips as filler were obtained and characterized. The influence of different factors (polymeric matrix type, fractional composition and geometrical characteristics of wood filler, processing parameters and ratio polymer/wood) on the properties of polymer–wood composites (PWCs) was studied. It was demonstrated that the packing factor F has an essential influence on the properties of PWCs: increasing F values determines an improvement in mechanical properties of these materials. Mechanical properties, thermal behaviour, morphological and diffusion characteristics of the analyzed composites were evaluated through specific methods and reported herein. Morphological and DSC data confirmed the presence of strong interface interactions between polymer and wood. The diffusion characteristics of PWCs showed that the diffusion coefficient D essentially depends on filler content in composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1700–1710, 2006     

Structural features of fibres from mixtures of rigid- and flexible-chain polymers from data of electron microscope and sorption methods

Conclusions The structure of fibres from mixtures of rigid- and flexible-chain polymers may vary from low-porosity to significantly porous on change in content of the flexible-chain polymer as a result of the structure of the flexible-chain polymer and the peculiar structural fibrillation which arises on separation of the polymers from solution.The ability of fibres based on CPA and 10% PCA to sorb water vapor is reduced as compared with that of the original fibres, which indicates the existence of rather strong intermolecular, interpolymer interactions.Translated from Khimicheskie Volokna, No. 4, pp. 34–36, July–August, 1987.     

Effect of radiation cross-linking on the thermomechanical properties of fibres from a tetrafluoroethyleneethylene copolymer

Conclusions The effect of radiation dose on the heat-resistance of fibres from a tetrafluoroethyleneethylene copolymer has been investigated.It has been shown that, as a result of irradiation, the use temperature of the fibres can be raised by 80°C.Translated from Khimicheskie Volokna, No. 1, pp. 37–38, January–February, 1988.     

Fabrication of sorption-active fibres based on hydrated cellulose-polyglycidyl methacrylate graft copolymer

Interpolation equations describing the depth of polymer-analog transformations of a graft copolymer as a function of the conditions of conducting the process were obtained using mathematical methods of design of experiments. The optimum parameters of polymer-analog transformations of HC—PGMA graft copolymer under the effect of thiourea and potassium thiocyanate were determined. The sorption-active fibres obtained in the optimum conditions have a RDC of 2.0–4.5 mmole/g. Translated fromKhimicheskie Volokna, No. 6, pp. 41–43,November–December, 1998.     

Spectrophotometric analysis of polymer mixtures based on a copolymer of acrylonitrile and a polyamido acid in dimethylacetamide

Conclusions An instrumental method of analysis of the composition and concentration of polymer compositions from mixtures of a copolymer based on acrylonitrile and a polyamido acid in dimethyl acetamide from their IR spectra has been proposed.The rapidity and selectivity of the method, and the possibility of carrying out the analysis directly on the object without use of auxiliary operations, made it possible to recommend it for serial analyses.Translated from Khimicheskie Volokna, No. 6, pp. 55–56, November–December, 1986.     

Rheological properties of melts and structure formation in polyoxymethylene-ethylene-propylene copolymer mixtures

Conclusions It has been shown that the conclusion of the Van Oene theory that the polymer with the greater melt elasticity should form a disperse type of structure and the polymer with the lower elasticity should form a stratified (laminar) structure is not fulfilled for polyoxymethylene-ethylene-propylene copolymer mixtures at ratios of 80:20 and 20:80. This means that at low content of the disperse phase polymer a disperse morphology is the most typical, regardless of the degree of elasticity of the melt.It has been found that an elevated elasticity of the disperse phase polymer does not aid specific fibre-formation.A disperse state of the polymer in a mixture and the formation of an interfacial layer lead to a decrease in the temperature (by tens of degrees) and heat effect (several-fold) of phase transitions.The interconnection between structure-formation processes and the rheological properties of the polymer mixture melt is manifested in a decrease in viscosity, an intensification of the viscosity anomaly, and an increase in the elasticity of the melt mixture as compared with these same characteristics of the starting polymers.Translated from Khimicheskie Volokna, No. 3, pp. 8–10, May–June, 1988.     

Synthesis and electro-optical properties of a new copolymer based on EDOT and carbazole

A new copolymer of 3,4-ethylenedioxythiophene (EDOT) and 5-(2-ethylhexyl)-1,3-bis(9-methyl-9H-carbazol-3-yl)-5H-thieno[3,4-c]pyrrole-4,6-dione (CzPDICz) was electrochemically synthesized using different monomer feed ratios. The resulting copolymer films were investigated in terms of their electrochemical and electro-optical behaviors. Properties of the obtained copolymer films through different monomer feed ratios were compared to each other and to individual poly(ethylenedioxythiophene; PEDOT) and homopolymer of CzPDICz in order to observe the differences in the properties with respect to PEDOT and P(CzPDICz). Copolymers exhibited well adherence on the electrode surface with having non-diffusional redox process. The monomer feed ratios were prepared as 9:1; 4:1, and 1:1 (EDOT:CzPDICz) and changes in the electrochemical and spectroelectrochemical behavior were noted with increasing CzPDICz ratio in the monomer mixture. Although no appreciable change in the optical band gap values of the copolymers was noted as compared to PEDOT, the neutral blue copolymers exhibited grayish color in their semi-oxidized states and transparent green in their fully oxidized states.