Three-dimensional printing is one of the most promising areas of additive manufacturing with a constantly growing range of applications. One of the current tasks is the development of new functional materials that would allow the manufacture of objects with defined magnetic, electrical, and other properties. In this work, composite magnetic filaments for 3D printing with tunable magnetic properties were produced from polylactic acid thermoplastic polymer with the addition of magnetic ferrite particles of different size and chemical composition. The used magnetic particles were cobalt ferrite CoFe2O4 nanoparticles, a mixture of CoFe2O4 and zinc-substituted cobalt ferrite Zn0.3Co0.7Fe2O4 nanoparticles (~20 nm), and barium hexaferrite BaFe12O19 microparticles (<40 µm). The maximum coercivity field HC = 1.6 ± 0.1 kOe was found for the filament sample with the inclusion of 5 wt.% barium hexaferrite microparticles, and the minimum HC was for a filament with a mixture of cobalt and zinc–cobalt spinel ferrites. Capabilities of the FDM 3D printing method to produce parts having simple (ring) and complex geometric shapes (honeycomb structures) with the magnetic composite filament were demonstrated.

The effect of oligophenylene sulfone (OPSU) and polycarbonate (PC) on the rheological, mechanical and thermal properties of polyetherimide (PEI) and a carbon-filled composite based on it was studied. It is shown that the introduction of OPSU and PC leads to a decrease in the melt viscosity of PEI and a carbon-filled composite based on it with the preservation of their mechanical properties and heat resistance at a sufficiently high level. It was found that composites with OPSU have higher mechanical and thermal properties compared with composites with PC. Samples from modified carbon-filled PEI were printed by the fused deposit modeling (FDM) method. Three-dimensionally printed samples from carbon-filled PEI modified by OPSU showed significantly higher mechanical properties than composites with PC.

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The effect of glass (GF) and carbon (CF) fibers of various linear sizes (0.2 and 3 mm) and concentrations on the properties of polyetherimide (PEI) has been studied. It is shown that the introduction of fibrous fillers leads to a decrease in the melt flow index, and to a greater extent in the case of fibers with a length of 3 mm. Also, it was found that both GF and CF lead to a decrease in toughness and an increase in the elastic-strength properties with a slight advantage of composites containing fibers of a length of 3 mm. In this case, GF composites have significantly higher properties. The study of heat resistance shows a slight decrease for composites with CF and the absence of influence of the filler for composites with HC, regardless of the size of the fibers.

Polyphenylene sulfones (PPSU) blends with different viscosities have been studied. It is shown that the blends have a single-phase structure, regardless of the viscosities of the mixed polymers. It was found that blends having close values of the melt flow index (MFR) are also characterized by a similar melt viscosity in a wide range of shear rates, regardless of the viscosities of its constituent components. It has been found that PPSU blends with smaller MFR differences exhibit higher heat resistance and stability of mechanical properties, while blends with similar viscosity containing oligomers exhibit a broader molecular weight distribution (MWD) and have lower thermal and mechanical properties.