Key Engineering Materials Vol. 899

Abstract: The article discusses the influence of the presence of polyurethane (elastomeric) threads in the composition of a textile material on the effect of plasma modification of hygroscopic properties. The objects of the study were textile (knitted) fabrics based on cotton fibers with the addition of Dorlastan threads. The samples were processed in the plasma of a high-frequency capacitive discharge at a reduced pressure, as the plasma-forming gas was used air. Experiments have shown that the water absorption of the samples after plasma treatment is increased by an average of 1.5 times. The presence of Dorlastan thread does not significantly affect the result of the plasma modification, since the samples are completely immersed in water and the elastomeric threads do not limit the water absorption of its cotton component. The degree of capillary rise, on the contrary, depends on the presence of polyurethane threads. In samples made of 100% cotton, the increase occurs up to 190-. According to these samples, polyurethane threads prevent the capillarity of water by about 4 times. Kinetic curves of water absorption are given. The results suggest that other processing treatments are required to render the polyurethane threads hydrophilicity by plasma treatment. This should be considered in the development of plasma methods for treating textile materials, including in terms of matrix for composite materials.

Abstract: The paper presents a comparison of the techniques for polydecylmethylsiloxane selective layer coating to the inner and outer sides of a polysulfone hollow fiber support. It has been shown that coating to the outer side allows one to obtain a composite membrane with a higher selectivity for CO₂/N₂ vapor. A decrease in the number of defects in the selective layer is achieved by increasing the viscosity of the polydecylmethylsiloxane solution. The resulting membrane was characterized in the separation of a model mixture of hydrocarbons, and a high separation selectivity was shown - 12.4 with respect to the n-butane / methane gas pair.

Abstract: The effect of blocked diisocyanates on the elastic-strength properties of elastomeric compositions based on SKI-3 isoprene rubber has been investigated. The synthesized additives are 2-isocyanato-4-phenylcarbamidotoluene (IPCT) and 2,4-diphenylcarbamidotoluene (DPCT). Tests were carried out to determine the physical and mechanical (conditional tensile strength, elongation at break, hardness) properties depending on the type and dosage of additives. It was found that samples with synthesized additives have strength and elongation at break higher than those of a sample without additives by 30 % and 200 %, respectively. There was also an increase in the tear resistance of all samples compared to the control (from 49.9 to 81.9 kN/m). An assumption is made about the formation of a network of physical connections, which provides an increase in these indicators. TMA analysis results showed a wider temperature range for reversible deformations (up to 180 °С).

Abstract: The article presents information on the synthesis of epoxy oligomers based on 2,2-di-(4-hydroxyphenyl) sulfone (DODPS) and hexachloroethane (HCE). We showed the results of a study of the adhesive properties and fire resistance of epoxy polymers. The synthesized sulfur-containing epoxy oligomers have a reasonably low viscosity and high fire resistance. Casting compounds obtained on their basis have improved performance characteristics.

Abstract: The work considers the main elements of the magneto-dimensional transformation properties in the ultradispersed metallic media (UDM) as a nanomodifier in the process of the formation of nanocompositional polymeric materials (NCPM) based on polyolefins () from a melt. It has been shown that UDM nanoparticles in a melt under the influence and interaction with a thermoplastic matrix are capable of transforming their magnetic properties (to the level of superparamagnetic), structural-dimensional parameters, and chemical potential. With this mutual influence, the nanomodifier has an active effect on the thermoplastic melt at all stages of the formation of the structure-property relationship: structureless ensembles of macromolecules → formation of clusters (domains), lamellas, crystallites → formation of a network of intermolecular entanglements → crystallization of the thermoplastic matrix → transition to a condensed state. An important component of the formation of a fine-crystalline anisotropic NCPM structure is the intramatrix orientation of the structural elements of the thermoplastic in the melt under the influence of the magneto-dimensional transformable manifestations of the nanomodifier. A consequence of the formation of a fine-crystalline anisotropic structure of the NCPM is an increased level of a complex of physicochemical properties (such as deformation-strength, rheological, etc.). An assumption is made about the possibility of the formation of coherent wave packets from clusters (domains) and lamellas of crystallites of matrix thermoplastic with a minimum three-dimensional geometry under the action of superparamagnetic forces of nanoparticles of the nanomodifier.

Abstract: Novel amphiphlic four-arm star-shaped poly (2-alkyl-2-oxazoline) s with calix [4] arene core were synthesized using the “grafting from” approach. The chlorosulfonated calix [4] arene derivative was synthesized and successfully applied as a multifunctional initiator for the cationic ring-opening polymerization of 2-alkyl-2-oxazolines. Obtained star-shaped poly (2-alkyl-2-oxazoline) s were characterized by means of NMR, UV-Vis spectroscopy and gel-permeation chromatography. It was shown that star-shaped poly (2-isopropyl-2-oxazoline) perform thermosensitivity in aqueous solutions.

Abstract: The influence of the multiplicity of extrusion and melt viscosity on the residual length of discrete carbon fibers in composites based on polyetherimide for 3D-printing is estimated. A technique for measuring the residual length of carbon fibers in composites is proposed. The residual length of carbon fibers in composites containing from 10 to 40% fibrous filler with different initial linear dimensions has been determined. It was found that the addition of a melt viscosity modifier to a carbon-filled composite helps to maintain the linear dimensions of the fiber filler particles, thereby increasing the physical and mechanical properties of the material.

Abstract: The article shows that synthetic wollastonite, obtained on the basis of a mixture of calcium oxide and silicon oxide, as well as calcium carbonate and silicon dioxide, increases the thermal stability of epoxy materials filled with it. The chemical and atmospheric resistance of epoxy films filled with wollastonite is on average 0.2 – 0.3% lower than that of the base composition, which is probably due to the porosity of both synthetic and natural wollastonite. The phase composition of synthetic wollastonite does not significantly affect chemical resistance of epoxy materials filled with it. The chemical resistance of epoxy compositions, regardless of their composition, is lower in weakly acidic solutions and water, in comparison with weakly alkaline and saline solutions.

Abstract: The wettability of reinforcing fillers such as glass and carbon fibers is a significant factor influencing the mechanical properties of the composite. This study focuses on the effect of finishing glass fiber surfaces with different concentrations of oligophenylene sulfide sulfone solution on fiber wettability, which is determined by contact angle and wetting time. The Adam-Schütte method was chosen as a method for determining the contact angle. According to the study results a 1.5% solution of oligophenylene sulfide sulfone in N, N'-dimethylacetamide gives a contact angle of 45°, forming over time a thin film on the fiber surface, which indicates a sufficiently high sizing ability.

Abstract: A new composite material based on fish gelatin (FG) was obtained by graft copolymerization of methylmethacrylate (MMA) onto fish gelatin. The process was initiated by radicals formed by the RbTe_1.5W_0.5O₆ photocatalyst under visible light (λ=400-700 nm) irradiation at room temperature. The characteristics of the new polymer material were obtained by the methods of elemental and physico-chemical analyses.