Vol 50, No 4 (2018)

Changes in the chemical composition of the solvent (Vaseline oil) as a result of its thermooxidative destruction were detected and investigated by UV and IR spectroscopy. It was found that an absorption band at ~270 nm, corresponding to the chromophoric C=O and C=C groups, appears in the electronic spectrum and increases in intensity during thermal destruction of Vaseline oil while absorption bands at 1720 and 1740 cm^-1, due to the appearance of terminal acid and aldehyde groups respectively, appear in the IR spectrum. The kinetics of the accumulation of chromophoric groups in relation to the experimental temperature was investigated, and a correlation was established between the intensity of the color of the solvent and the concentration of chromophoric groups.

The basic principles of information modeling are examined as systems engineering technology for producing carbon fibers (CFs) with given properties. The concept of a fiber system is introduced based on general system theory. The fundamental systems of the polymer fiber precursors and CFs based on them are represented as composites. The properties of the produced CFs can be controlled in two ways, i.e., by performing technological transitions during CF preparation as composites and by affecting each of the materials of the technological procedure, including use of the observed effect to change the properties of the polymer fiber—precursor system during its subsequent heat treatment. Information modeling is found to be highly efficient in practice for producing CFs with high electrical conductivity from poly(para-phenylene-1,3,4-oxadiazole).

Light scattering, turbidimetry, and viscosimetry have been used to study aqueous solutions of poly-2-isopropyl-2-oxazolines differing in the structure of their hydrophobic terminal groups. The phase separation temperature was determined. A complex temperature dependence was found for the viscosity of these solutions featuring an inflection point near the phase separation temperature. The addition of polyacrylic acid to a solution of poly-2-isopropyl-2-oxazoline has only a weak effect on the phase transition temperature but has a considerable effect on the viscosity of the system.

The results are presented from investigations into the effect of oxidative treatment of carbon nanotubes on the physicochemical and catalytic characteristics of gold, ruthenium, and platinum catalysts deposited on them. The surface of multiwalled carbon nanotubes was functionalized in an acidified solution of potassium permanganate. The physicochemical characteristics of the carbon nanotubes and deposited catalysts were studied by the following methods: BET (the Brunauer–Emmet–Teller method), TPR-H (temperature-programmed reduction with hydrogen), XPA (x-ray diffraction), Fourier IRS (infrared spectroscopy with Fourier transformation), TGA (thermogravimetric analysis), scanning electron microscopy (SEM), and chemisorptions of CO and H₂. The catalytic activity was determined in a flow-type quartz reactor in the range of 250-300°C at atmospheric pressure.

The main approaches to designing environmentally friendly technologies for the preparation, coloring and finishing of textile materials are shown, which can be implemented in production of ecotextiles.

Samples of composites based on epoxy resin and sunken-loop knit fabric with satin and lasting 1+1 interlocking are investigated. It is shown that the strength anisotropy coefficient of the composite can be counted as a double ratio of the knit fabric density along the course to the knit fabric density along the wale. The extensibility of the knit fabric does not have a significant effect on the strength of the composite reinforced by it. The maximum strength of the composite is attained when the loop modulus is above 50. In mechanical properties, composites with a knit fabric filler are close to composites with quasi-continuous reinforcement, for example, with individual unidirectional threads.

We consider targeted variation of the relaxation state for polymer components of wood in stages of the life cycle of corrugated cardboard. From the standpoint of the structural physicochemistry of wood, we present a mechanism for the processes occurring in traditional corrugated cardboard production technology. Our thesis is that cellulose and hemicellulose can go from the glassy state to the rubbery (highly elastic) state at 220°C, but under real conditions this transition occurs at room temperature and even at negative temperatures in the case of plasticization by a sufficient amount of water. Transition of lignin from the glassy state to the rubbery state occurs at a temperature above 130°C, and at 70°C-120°C under conditions of sufficient hydration. Formation of strong interfiber bonds is possible only when the polymers forming the contact are in the rubbery or viscous-flow state.

Hydroxyethyl cellulose is modified with organobentonite particles using mechanical dispersion to produce polymer films. The effect of filler concentration on the structure, strength, and biological activity of the polymer composites was studied.

The processes of thermal oxidation and carbonization of copolyamide benzimidazole (CPB) fibers were investigated, structural and chemical transformations were characterized by thermogravimetry, IR spectroscopy, elemental analysis, atomic force microscopy, and physicomechanical and electrophysical properties. Fiber hardening was found to occur on treatment at low-temperatures in air. It was shown that the preliminary oxidation of CPB fibers has practically no effect on the carbonization of the polymer. Impedance studies have confirmed that structural chemical modification leads to a decrease in the active resistance of the polymer fiber.

The effect of talc and various polymer additives on the basic mechanical properties of polyphenylene sulfone was studied. It was found that with an increase in the concentration of the filler, there is an increase in the elastic strength and a decrease in the plastic properties of polyphenylene sulfone. The physicomechanical properties of various polymer-polymer composites based on polyphenylene sulfone are considered. High efficiency of polycarbonate as a modifier of toughness is revealed. An efficient method has been developed for producing a composite with high values of impact strength and modulus of elasticity, based on the characteristics of the distribution of the filler in the polyphenylene sulfone polycarbonate binary system. It is shown that the concentration of the filler in the polycarbonate phase reduces the impact strength, whereas its concentration in the polyphenylene sulfone phase followed by the introduction of polycarbonate results in an impact-resistant and high modulus composite. Samples obtained by the 3D printing method exhibit high mechanical characteristics.