Key Engineering Materials Vol. 869

Abstract: Dense membranes made of polybenzodioxane (PIM-1) were developed for pervaporation of toluene/TEG mixtures. The effect of experiment time on membrane characteristics such as flux and separation factor was investigated. The neat PIM-1 membranes showed high toluene flux of 2.45 kg/m²∙h, but low separation factor of 4. The cross-linking of PIM-1 using AlCl₃ leads to an increase in the separation factor up to 20, with some compromise of toluene flux down to 0.76 kg/m²∙h.

Abstract: A highly corrosion resistant and conductive polymer coating for polymer electrolyte membrane fuel cells bipolar plates have been successfully prepared from renewable plant biomass sources. The coating is based on the 5-hydroxymethylfurfural synthesis by-product resin that consists of complex furanic oligomers and polymers. The corrosion resistance and conductivity of coated titanium plates have been studied. As-prepared coated Ti samples are shown 0.083 μA/cm² and 0.32 μA/cm² corrosion current in the simulated PEMFCs cathode and anode environment respectively. In addition, the polymer coating are reduced the interfacial contact resistance of bare titanium up to 40 %. The Ti plates coated with by-products of 5-HMF synthesis are shown a great potential application as bipolar plates for PEMFCs.

Abstract: Polymer composite materials (PCМ) based on low molecular weight siloxane rubber SKTN-A have been developed, which are supposed to be used as osteoplastic materials in maxillofacial surgery. The following materials were used as fillers for the creation of PCM: bentonite, sepiolite, wollastanite. The effect of the type and content of filler on the curing process and the properties of the resulting compositions was investigated.

Abstract: The effect of new adhesion promoters on the bond strength of rubber compounds with rubber cord based on synthetic isoprene rubber SKI-3, as well as on the structure of their vulcanizates, is investigated. The synthesized additives were taken as adhesion promoters: 2,4-diphenylcarbamidotoluene (DPKT); 2-isocyanatophenylcarbamidotoluene (IPCT) and the industrial promoter is Manobond 680C. Tests were conducted to determine the adhesion strength to the metal cord and the density of the cross-linking of the obtained rubber compounds by the dosage of additives. It is determined that the maximum value of adhesion had mixture containing 1.2 parts by weight of 2-isocyanato-phenylcarbamidotoluene and Manobond 680C. It was found that the introduction of additives DPCT and IPCT leads to the formation of additional cross-links in the vulcanizates. Rubbers containing additives in an amount of 0.4-1.2 parts by weight have the highest density of crosslinking. The studies made it possible to hypothesize the relationship between the particle size and the electrokinetic potential of blocked urea-based isocyanates with the strength of brass-metal cord-rubber bonding. The results obtained indicate that the greater the electrokinetic potential of the synthesized additives and the lower the average particle size, the better the additive is distributed in the rubber compound and affects the formation of the adhesive layer at the brass-metal cord-rubber interface.

Abstract: Composite membranes were prepared for nanofiltration of aromatic solvents. Cross-linking with AlCl₃ was used to improve the stability of the PIM-1 selective layer in aromatic solvents like toluene, benzene and xylene. Nanofiltration performances of obtained membranes were tested with 4 different aromatic hydrocarbons and with 3 solvents from other classes of solvents. Obtained permeability for aromatic hydrocarbons was above 8,5 kg/m²·h·bar and retention of Remazol brilliant blue R dye with molecular mass 626 was up to 96 %. It was shown that permeability results correlated with Hansen solubility parameter and distance parameter between polymer and solvent. PIM-1 has higher permeability for non-polar hydrocarbons due to higher affinity between polymer and solvent.

Abstract: PAN membranes were prepared from mixture of good and weak solvents by two different methods. Immersion precipitation method with and without volatile component evaporation used for membrane preparation. From analysis of Hansen solubility parameters DMSO chosen as good solvent and acetone chosen as weak solvent. The effect of volatile weak solvent investigated on pore size and filtration performance. By evaporation of acetone, it was possible to increase polymer concentration on casting solution and obtain smaller pore size in comparison to membrane prepared from DMSO. Membranes prepared from DMSO/acetone without solvent evaporation had even lower pore size and higher filtration performances. It was shown, that presence of acetone creates more pronounced effect on pore size than increase of polymer concentration. As a result membranes with pore size 3.7 nm obtained from Acetone/DMSO mixture with composition 50:50 and polymer concentration 50 % by immersion precipitation Resulted membranes have permeance 23 kg/m²·h·bar and retention of Lysozime 99 %.

Abstract: The spinning solution properties (viscosity, chemical composition) can be varied depending on the method of its preparation. These variations might cause changes in the thermodynamics and kinetics of the phase separation process during the membrane formation. In this work, the influence of various modes of spinning solution preparation on the morphology, geometric and gas transport properties of the resulting polysulfone (PSf) hollow fiber membranes was investigated. The differences in methods of solution preparation were the temperature and time of stirring. It was found that with the transition to the lower-temperature stirring of the spinning solution the outer diameter and wall thickness of the fiber increase, and the thickness of the selective layer decreases. The highest ideal selectivity values are observed with the solution stirring for 5 hours at temperature 120 °С (3.1 for pair He/CO2). The maximum values of the gas permeability are achieved in the mode of the solution stirring for 24 hours at temperature 50 °C (P/l (He) = 201 m3/( m2∙h∙atm); P/l (CO2) = 83 m3/( m2∙h∙atm)).

Abstract: The paper uses waste from the production of synthetic rubbers, industry, various clays for effective ways to solve the socio-economic and environmental problems of preserving natural resources and preventing environmental pollution. The construction materials industry faces the most important task-the search for non-deficit raw materials that allow partially or completely eliminate expensive conditioned polymers, rubbers and obtain cheaper mastic roofing materials while maintaining their high physical, mechanical and operational properties. Thermomechanical curves of composite materials based on synthetic rubbers with additives were studied. It is shown that the softening of samples of roofing materials No. 325 and No. 326 begins at , 20 % deformation is achieved, respectively, at – (No. 325) and + (No. 326), a sharp increase in deformation is observed, respectively, with a loss of strength: 40 % (No. 325) and 20 % (No. 326). Based on these materials, reinforced mastic roofs have been developed, which have low values of crack resistance. The coefficient of water resistance depends on the base, i.e. the reinforcing materials.

Abstract: This article presents a scientific review of the literature on the production of polyether ketones and copolymers of various structures with a complex of valuable properties. Particular attention is paid to the synthesis of polyether ketones by electrophilic substitution by the Friedel-Crafts reaction mechanism.

Abstract: The article is a literature review on 3D-printing of crystalline polyether ether ketone by the methods of layer-by-layer deposition of molten polymer filament (FDM) and selective laser sintering (SLS). The influence of printing technological modes and material properties (fluidity, morphology, etc.) on the quality of the products is considered.