Powder Injection Molding (PIM) is a versatile manufacturing technology widely used for fabricating components with complex geometries from metals and ceramics, yet its application to high-performance thermoplastics remains underutilized. This study explores the feasibility of manufacturing products from Polyphenylene Sulfide (PPS)-a promising linear aromatic polymer synthesized in powder form-using PIM technology and investigates the development of PE-based feedstocks with PPS and solid fillers. Regarding the matrix formulation, it was found that using pure paraffin as a binder limited the maximum PPS content to 20%. Consequently, a modified binder system consisting of Low-Density Polyethylene (LDPE) and paraffin in a 70:30 wt.% ratio was utilized, which successfully increased the PPS loading in the feedstock to 50% and enabled stable molding. Following matrix optimization, the study examined composites incorporating various fillers, including chalk, talc, and carbon fibers. Systematic rheological analysis confirmed that these composite suspensions possess characteristics necessary for molding products with complex geometries. Key results indicate that optimal sintering conditions were established to achieve the required mechanical properties. Among the tested fillers, carbon fibers were the most effective reinforcement, increasing the elastic modulus by 33% and flexural strength by 20%. Representative examples of samples successfully manufactured via this approach are presented.

The use of polymers in radiation zones of reactors and particle accelerators is rather limited due to the established opinion about the relatively low radiation resistance inherent in organic materials. However, the development of a new class of aromatic polymers, polyetheretherketone and its relatives, has decisively changed this opinion. They retain unique high mechanical and thermal stability up to absorbed doses of γ-irradiation of several MGy. This paper compares the effects of γ-radiation and high-intensity electron beams. As shown, both types of radiation lead predominantly to cross-linking of polyetheretherketone (PEEK), polyphenylene sulfone (PPS), and polyetherimide (PEI) macromolecules. This is manifested in changes in both the rheological and thermal properties of plastics. The total yields of extracted degradation products do not exceed 1 nmol J−1. Although the electron beam delivers a dose rate 8.1 × 10⁵ times higher than gamma radiation, both types of radiation have only a minor effect on the strength of PEEK and PPSU. The mechanism of key radiolytic transformations is discussed. The main reasons for the high radiation resistance of PEEK and PPSU are the cage effect, the high protective properties of aromatic units and bond conjugation systems, as well as extremely low gas permeability. Cross-linking is initiated primarily by intramolecular and intermolecular redistribution of H atoms. The high radiation resistance of the studied polymers confirms their potential for use in nuclear and radiation technologies, in radiation zones of charged particle accelerators, and in spacecraft operating in high-intensity radiation fields.

The influence of the molecular weight and chemical structure of polyphenylene sulfone (PPSU) end groups on the formation of the porous structure of ultrafiltration (UF) hollow fiber membranes was investigated. Polymers with a molecular weight ranging from 67 to 81 kg/mol and with a hydroxyl-to-chlorine end group ratio ranging from 0.43 to 17.0 were synthesized. The excess of end groups was achieved during polymer synthesis by adding one of the following monomers: hydroxyl (excess DHBP) or chlorine (excess DCDPS). For the first time, it was found that the stability of PPSU solutions is determined not by the molecular weight of the polymer, but by the chemical structure of its end groups. The stability of polymer solutions increases with the increasing proportion of chlorine groups. The SEM method showed that with the increasing molar fraction of chlorine end groups in the polymer, a more open porous structure forms on the outer surface of the hollow fiber membranes derived from it. The maximum UF permeance of the hollow fiber membranes for water was achieved with the PPSU sample containing the highest chlorine end group content, amounting to 136 L/(m2·h·bar), with a high rejection of the model substance Blue Dextran (at 94.7%). This represents the best result currently reported among unmodified PPSU hollow fiber membranes.

Polymer–polymer composites based on poly(ether ketone ketone) and polyphenylenesulfone have been investigated for the first time. It has been shown that the blends exhibit a single relaxation vitrification transition up to the 50 : 50 composition, which evidences good compatibility of poly(ether ketone ketone) and polyphenylenesulfone in the amorphous phase. Slight phase separation has been observed at the 50 : 50 and 30 : 70 ratios, reflected in significant broadening of the glass transition regions in the differential scanning calorimetry and dynamic mechanical analysis curves. It has been shown that an increase in the content of polyphenylenesulfone leads to an increase in the glass transition temperature and the heat deflection temperature. Furthermore, polyphenylenesulfone has prevented the crystallization of poly(ether ketone ketone), which has been accompanied by an increase in the crystallization temperature and a decrease in the degree of crystallinity. It has been revealed that the introduction of polyphenylenesulfone leads to a gradual decrease in the mechanical parameters measured at low strain, the changes of which have followed the additivity rule. On the contrary, the strain has been more sensitive to the phase structure; it has been significantly decreased upon the appearance of the phase separation, more pronounced at the 50 : 50 composition.

In this study, we employed fused deposition modeling (FDM) to fabricate polylactide (PLA) composites with 5 wt% and 10 wt% of CoFe2O4 (CFO) magnetic nanoparticles. The structural, mechanical, and magnetic properties of these nanocomposites were studied. Tensile testing revealed that as the concentration of CFO increased, both the tensile strength, from 26 MPa to 7 MPa, and deformation limits, from 4 % to 1 %, decreased. However, atomic force microscopy analysis showed an increase in the average Young's modulus of the surface. The results of magnetic measurements demonstrated that 3D technique enables one to controllably print the patterns which serve as the sources of local magnetic fields of complex geometries.

The rheological properties of suspensions based on paraffin and LDPE, in which polyphenylene sulfone powder is dispersed, intended for powder injection molding and 3D printing were studied. Compositions with a polymer content of up to 50 vol

Systematic studies of the influence of the basic powder characteristics and its sintering conditions on the physical and mechanical properties of samples intended for the implementation of the technology of powder injection molding of products from typical heat-resistant high performance engineering polymers - crystallizing polyetheretherketone (PEEK) and amorphous polyphenylene sulfone (PPSu) - were carried out. Polymers with different MW were synthesized as initial materials and powders with different sizes and bulk density were obtained. The influence of these parameters on the nature of powder sinterability and, as a consequence, on their elastic modulus and tensile strength was shown. Optimum characteristics for bulk density and sintering temperature were established, which provide maximum values of mechanical characteristics of the molded samples. The results of the fundamental research conducted allowed us to produce two typical products for biomedicine - an intervertebral cage (an implant replacing a removed vertebra) and a blood dialyzer part.

In order to study the influence of the nature of the catalyst on the production process and the physicochemical properties of polyethylene terephthalate, samples were synthesized using catalysts based on antimony and titanium. Optimal catalyst concentrations were established for the production of polyethylene terephthalate with values close to those of industrial designs EKOPET samples: the characteristic viscosity (0.55-0.75 dl/g), melting temperature (max. 256°С), color number (L* ≥ 82.0; b * -1.5 ± 2.0) and acetaldehyde content (max. 1.0 ppm). The structure and properties of synthesized polyethylene terephthalate samples were studied using the methods of infrared spectroscopy and differential scanning calorimetry; transparency (L*) and color (b*) indicators, intrinsic viscosity, the amount of diethylene glycol, acetaldehyde and the content of terminal carboxyl groups were determined. Questions about the influence of nature, as well as the quantitative ratio of the catalyst on the indicators of color, transparency, intrinsic viscosity and the content of terminal carboxyl groups were discussed. It was revealed that titanium-containing compounds, in comparison with antimony catalysts, increase catalytic activity, which helps reduce the duration of the production process and produce polyethylene terephthalate with high molecular weight characteristics.

High-performance aromatic heterochain polymers are engineering thermoplastics with exceptional mechanical and thermal properties that have attracted great interest in various areas ranging from aerospace to biomedicine. However, there have been a number of difficulties to 3D-print materials based on such polymers with new promising performance characteristics. Herein, a number of new photosensitive compositions (PSCs) based on high-performance polyetherimide (PEI) or polysulfone (PSU), reactive functional monomer (N,N-dimethylacrylamide) and oligomer (bisphenol A ethoxylate diacrylate) has been developed. It has been shown that the use of the developed PSCs allows the formation of 3D-structures with high printing resolution by LCD 3D-printing. Subsequent thermal post-curing of 3D-printed green-state samples at 250 degrees & Scy; for 1 h led to the fabrication of materials with the highest tensile strength (up to 41.9 +/- 3.1 MPa), glass transition temperature (141 degrees C) and thermal stability (above 350 degrees C). In addition, 3D-printed structures demonstrate high-temperature shape memory effect with shape fixity ratio > 99% and shape recovery ratio up to 97.1%.

For the first time, copolymers of polyphenylene sulfone (PPSU) with cardo fragments of phenolphthalein (PP) were synthesized to develop highly permeable flat-sheet ultrafiltration membranes. By introducing cardo fragments into the polymer chain, we achieved a mechanical strength 1.3 times higher than the strength of commercial PPSU. It is shown that the introduction of the cardo monomer significantly increases the solubility of the polymer in aprotic solvents. The highest solubility is observed at the concentration of PP 50 mol.%. It is found that reduced viscosity of cardo polymer solutions leads to an increase in the coagulation rate. The permeance of asymmetric ultrafiltration membranes increases with PP concentration from 17.5 L/(m2·h·bar) (10 mol.% PP) to 85.2 L/(m2·h·bar) (90 mol.% PP). These data are in agreement with the results of a study of the coagulation rate of polymer solutions. Thus, for ultrafiltration membranes with 1.5–8 times higher permeance in comparison with PPSU due to the introduction of cardo fragments in the polymer chain, possessing high rejection of the model dye Blue Dextran (MW = 70,000 g/mol), more than 99.2%, as well as high strength characteristics, were achieved.

The main goal of the work was to use rheological methods for assessing the properties of a composition based on polyether ether ketone (PEEK) to determine the concentration limits of the polymer in the composition and select the optimal content of this composition for powder molding. The rheological properties of highly filled suspensions based on PEEK and paraffin, as well as in paraffin–polyethylene mixtures at various component ratios, were studied. These materials are designed for powder injection molding and 3D printing. Suspensions with a PEEK powder content above 50% are not capable of flow and, with increasing pressure, slide along the surface of the channel. For compositions with a higher content (60 and 70 vol.%) PEEK, independence of the storage modulus from frequency is observed, which is typical for solids and confirms the assignment of such suspensions to elastic–plastic media. The introduction of high-density polyethylene into the composition helps improve the technological properties of suspensions, expanding the range of fluidity, although it leads to an increase in viscosity. In suspensions with a mixed composition of the liquid phase, with increasing temperature, a decrease in the storage modulus is observed at 120 °C and, on the contrary, an increase at 180 °C. The latter may be a consequence of the evaporation of paraffin and the softening of PEEK due to the approach to the glass transition temperature of the polymer. Suspensions with 40% PEEK content have an optimal set of rheological properties for powder injection molding. A 3D printing filament was also obtained from a composition with 40% PEEK, which had good technological properties for FDM 3D printing. Products of satisfactory quality from suspensions with 50% PEEK can be produced by powder injection molding, but not by 3D printing. The selected compositions were used to obtain real PEEK products for practical applications.

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For the first time, poly(phenylene sulfones) (PPSFs) with chlorine and hydroxyl terminal groups are synthesized and tested for casting high-performance flat-sheet ultrafiltration membranes. The synthesis of PPSFs is carried out in dimethylacetamide at various ratios of 4,4'-dihydroxydiphenyl and 4,4-dichlorodiphenyl sulfone monomers. Two samples with the predominant content of hydroxyl (PPSF-ОН) and chlorine (PPSF-Cl) terminal groups are studied by NMR spectroscopy, GPC, and DSC methods. The coagulation values of polymer solutions in N-methyl-2-pyrrolidone (NMP) and the mechanical properties and hydrophilicity of polymer materials are determined. Both PPSF samples exhibit high tensile strength values at a level of 16 MPa. Using the method of precipitation of PPSF solutions in NMP with PEG-400 additives into water flat-sheet porous asymmetric membranes with a mesoporous (a pore diameter of about 7 nm) thin outer layer and fingerlike macropores in the substrate layer are obtained. An increase in the proportion of hydroxyl terminal groups enhances the hydrophilicity of the polymer. This, in turn, allows for the preparation of flat-sheet membranes from PPSF-ОН with a water permeability of 66 L/(m2 h bar), which is 1.5 times higher than the water permeability of the PPSF-Cl membrane. Meanwhile, both membranes demonstrate a Blue Dextran (Mw = 70 000 g mol–1) rejection of 99.9

For the first time, for the problem of high-performance ultrafiltration flat-sheet membranes casting, polyphenylene sulfones (PPSF) with chlorine and hydroxyl terminal groups were synthesized and studied. The synthesis of PPSF was carried out in dimethylacetamide at different ratios of 4,4′-dihydroxydiphenyl and 4,4-dichlorodiphenylsulfone monomers. Two samples with a predominant content of hydroxyl and chlorine terminal groups, PPSF-OH and PPSF-Cl, were studied using NMR, GPC and DSC methods. The coagulation values of polymer solutions in N-methyl-2-pyrrolidone (NMP), the mechanical properties and hydrophilicity of the materials were also determined. Both PPSF samples have high strength modulus (16.0–16.6 MPa). Using the method of deposition in water of PPSF solutions in NMP with PEG-400 additives, flat-sheet porous asymmetric m embranes with a mesoporous (diameter of about 7 nm) thin outer layer and finger-like macropores in the substrate were obtained. An increase in the proportion of –OH terminal groups increases the hydrophilicity of the polymer. This, in turn, made it possible to obtain flat-sheet membranes based on PPSF-OH with a water permeability of 66.1 l/m2 h bar, which is 1.5 times higher than the water permeability of the PFSF-Cl membrane. At the same time, both membranes demonstrate the Blue Dextran (Mw = 70,000 g mol–1) rejection of 99.9%.

Polyetheretherketones with various molecular weights were obtained by high-temperature polycondensation using the nucleophilic substitution reaction by varying the temperature-time mode of synthesis. The thermal, physico-mechanical properties, bulk density, shape and size of particles were studied. The polyetheretherketone synthesis conditions, which make it possible to obtain a polymer powder with a set of properties necessary for high-quality 3D printing using selective laser sintering technology, were determined.

3D printing of polyolefins, such as polyethylene (PE) and polypropylene (PP), is of great practical interest due to the combination of high properties of these materials. However, the use of these materials in 3D printing is associated with many problems due to their high rate of crystallization, which causes shrinkage and warpage of the printed object. In this regard, blends of PE and ethylene-vinyl acetate copolymer (EVA) of various compositions were investigated for 3D printing. It was found that with an increase in the concentration of EVA, an increase in the pseudoplastic effect and amorphization of PE occurs. It has been shown that with an increase in the EVA content, the degree of crystallinity of PE decreases slightly (by 11% at a content of 80% EVA); however, a significant decrease in the rate of crystallization of PE is observed (by 87.5% at the same EVA concentration). It was found that PE and EVA are completely compatible in the amorphous phase and partially compatible in the crystalline phase, which leads to a slight decrease in the melting point of PE. The introduction of EVA also leads to a significant increase in impact strength: the maximum value is achieved at a 50/50 ratio, which is five times the value of the initial PE and two times the value of the initial EVA. At the same time, it was revealed that EVA leads to a gradual decrease in the elastic modulus and strength of PE, the change of which generally obeys the additivity rule. The resulting printing filaments are characterized by a certain ovality due to their shrinkage, which decreases with increasing EVA content and reaches a minimum value at a PE/EVA ratio of 30/70. This composition also demonstrates the lowest shrinkage of the printed sample and higher processability during printing.

For the first time, the effect of the solvent and monomer ratio on molecular weight, chemical structure, and mechanical, thermal, and rheological characteristics of polyphenylene sulfone has been studied. When dimethylsulfoxide (DMSO) is used as a solvent, cross-linking occurs during the processing of the polymer, which is accompanied by an increase in melt viscosity. This fact sets a pressing need for the complete removal of DMSO from the polymer. The best solvent used for the production of PPSU is N,N-dimethylacetamide. This study of the molecular weight characteristics of polymers by gel permeation chromatography showed the stability of the polymers practically does not change with a decrease in molecular weight. The synthesized polymers correspond in tensile modulus to the commercial analog Ultrason-P, while exceeding it in terms of tensile strength and relative elongation at break. Thus, the developed polymers are promising for spinning hollow fiber membranes with a thin selective layer.

For the first time, for the problem of hollow fiber membranes spinning, polysulfones in a wide range of molecular weights (42 000–184 000 g/mol) were synthesized in such aprotic dipolar solvents as dimethylacetamide, N-methyl-2-pyrollidone, and dimethyl sulfoxide. The dependence of the thermal and mechanical properties of polysulfones on molecular weight characteristics has been studied. A comparison of the mechanical properties of the synthesized PSF, commercial PSF Ultrason S 6010 (BASF, Germany) and PSF-150 (JSC Institute of Plastics, Russia) showed that the synthesized polymers are not inferior to commercial analogues. Some synthesized polymers surpass commercial PSF in terms of elasticity and strength modulus. Based on the study of the spinning solutions dynamic viscosity, promising PSF samples were selected for the formation of porous hollow fiber supports. It was found that hollow-fiber porous support from a PSF sample with a molecular weight of 110 000 g/mol have a high nitrogen permeability of 47.5 m3/m2 · h · bar. Such supports are promising for casting highly permeable composite membranes with a thin selective layer.