The aim of this study was to optimize a set of technological parameters (travel speed, extruder temperature, and extrusion rate) for 3D printing with a PEEK-based composite reinforced with 30 wt.% glass fibers (GFs). For this purpose, both Taguchi and finite element methods (FEM) were utilized. The artificial neural networks (ANNs) were implemented for computer simulation of full-scale experiments. Computed tomography of the additively manufactured (AM) samples showed that the optimal 3D printing parameters were the extruder temperature of 460 °C, the travel speed of 20 mm/min, and the extrusion rate of 4 rpm (the microextruder screw rotation speed). These values correlated well with those obtained by computer simulation using the ANNs. In such cases, the homogeneous micro- and macro-structures were formed with minimal sample distortions and porosity levels within 10 vol.% of both structures. The most likely reason for porosity was the expansion of the molten polymer when it had been squeezed out from the microextruder nozzle. It was concluded that the mechanical properties of such samples can be improved both by changing the 3D printing strategy to ensure the preferential orientation of GFs along the building direction and by reducing porosity via post-printing treatment or ultrasonic compaction.

The aim of the paper was to improve the functional properties of composites based on ultra-high molecular weight polyethylene (UHMWPE) by loading with reinforcing fibers. It was achieved by designing the optimal composition for its subsequent use as a feedstock for 3D-printing of guides for roller and plate chains, conveyors, etc. As a result, it was experimentally determined that loading UHMWPE with 17% high density polyethylene grafted with VinylTriMethoxySilane (HDPE-g-VTMS) was able to bind 5% glass fillers of different aspect ratios, thereby determining the optimal mechanical and tribological properties of the composites. Further increasing the content of the glass fillers caused a deterioration in their tribological properties due to insufficient adhesion of the extrudable matrix due to the excessive filler loading. A multi-level approach was implemented to design the high-strength anti-friction ‘UHMWPE+17%HDPE-g-VTMS+12%PP’-based composites using computer-aided algorithms. This resulted in the determination of the main parameters that provided their predefined mechanical and tribological properties and enabled the assessment of the possible load-speed conditions for their operation in friction units. The uniform distribution of the fillers in the matrix, the pattern of the formed supermolecular structure and, as a consequence, the mechanical and tribological properties of the composites were achieved by optimizing the values of the main control parameters (the number of processing passes in the extruder and the aspect ratio of the glass fillers).

A comparative analysis on structure, mechanical and tribological properties of a multicomponent extrudable polymer composites "UHMWPE + 17 wt. % HDPE-g-SMA + 12 wt. % PP" fabricated by i) FDM (fused deposition modeling) as well as hot pressing of ii) powder mixture, and iii) granules of the same composition has been conducted. It is shown that UHMWPE composites obtained by the 3D–printing over a complex of tribomechanical properties (wear resistance, friction coefficient, elastic modulus, yield point, tensile strength, elongation at break) are comparable with those of composites fabricated by compression sintering of granules (this is associated with formation of more homogeneous permolecular structure, first of all, due to the compounding with the help of a twin-screw extruder) and significantly exceed those for hot pressing of powder mixtures. The obtained results allow one to recommend this composite for manufacturing complex shape products for tribotechnical application at employing 3D-printing technologies.

In this study, a structural and functional analysis was conducted to investigate antifriction multicomponent polymer composites on the basis of ultrahigh-molecular polyethylene (UHMWPE) developed as feedstocks for additive manufacturing of friction parts operating under extreme conditions. The aim was to make UHMWPE extrudable by selecting appropriate polymer plasticizers. An algorithm is proposed for the development of extrudable UHMWPE-based composites with a minimum amount of experimental data available. The algorithm determines the control parameters that provide required characteristics of multicomponent polymer materials and thereby ensure the achievement of desired tribological, mechanical and processing properties. The dependence of the experimentally determined characteristics versus the control parameter values is analyzed, and corresponding response surfaces are constructed in the state space. The surfaces reveal the range of the control parameter values that ensure the achievement of specified properties. The algorithm is applied to select an optimal composition of the ternary "UHMWPE+ 17 wt% HDPE-g-SMA + 12 wt% PP" mixture, whose tribological and mechanical behavior is similar to that of unfilled UHMWPE, but the melt flow is good enough for 3D printing. A comparative study is carried out on structural, mechanical and tribological properties of the multicomponent "UHMWPE+ 17 wt%HDPE-g-SMA+ 12 wt% PP" composites fabricated by FDM printing and hot pressing. It is shown that the tribological and mechanical properties of 3D-printed extrudable UHMWPE-based composites exceed the properties of composites obtained by compression sintering, which is due to the formation of more homogeneous permolecular structure with increased crystallinity. The tribological characteristics of the 3D-printed composites are studied under various friction test conditions (P*V). The composites are proposed as suitable for friction parts operating in a wide range of speeds and loads.