Three-Component Wear-Resistant PEEK-Based Composites Filled with PTFE and MoS2: Composition Optimization, Structure Homogenization, and Self-lubricating Effect

The aim of this work was to design and optimize compositions of three-component composites based on polyetheretherketone (PEEK) with enhanced tribological and mechanical properties. Initially, two-component PEEK-based composites loaded with molybdenum disulfide (MoS2) and polytetrafluoroethylene (PTFE) were investigated. It was shown that an increase in dry friction mode tribological characteristics in metal-polymer and ceramic-polymer tribological contacts was attained by loading with lubricant fluoroplastic particles. In addition, molybdenum disulfide homogenized permolecular structure and improved matrix strength properties. After that, a methodology for identifying composition of multicomponent PEEK-based composites having prescribed properties which based on a limited amount of experimental data was proposed and implemented. It was shown that wear rate of the “PEEK + 10% PTFE + 0.5% MoS2” composite decreased by 39 times when tested on the metal counterpart, and 15 times on the ceramic one compared with neat PEEK. However, in absolute terms, wear rate of the three-component composite on the metal counterpart was 1.5 times higher than on the ceramic one. A three-fold increase in wear resistance during friction on both the metal and ceramic counterparts was achieved for the “PEEK + 10% PTFE + 0.5% MoS2” three-component composite compared with the “PEEK + 10% PTFE”. Simultaneous loading with two types of fillers slightly deteriorated the polymer composite structure compared with neat PEEK. However, wear rate was many times reduced due to facilitation of transfer film formation. For this reason, there was no microabrasive wear on both metal and ceramic counterpart surfaces.

Three-Component Composite Based on Ultra-High Molecular Weight Polyethylene for Additive Manufacturing

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.

Improvement of Wear Resistance of UHMWPE by Adding Solid Lubricating Fillers

For estimating effectiveness of adding solid fillers for composites with ultra-high molecular weight polyethylene matrix tribotechnical characteristics of UHMWPE mixture with graphite, molybdenum disulfide and polytetrafluoroethylene were investigated under dry friction, boundary lubrication and abrasion. The optimum filler weight fraction was determined in terms of increasing wear resistance. Permolecular structure and surface topography of wear tracks for UHMWPE composites with different weight fraction of the fillers was studied. The mechanisms of wear of polymeric composites “UHMWPE-graphite”, “UHMWPE-PTFE” and “UHMWPE-MoS2” under dry sliding friction and abrasive wear are discussed.

Influence of Nano- and Microfillers on the Mechanical and Tribotechnical Properties of “UHMWPE-PTFE” Composites

In order to develop antifriction extrudable composites with micro-and nanosize fillers the mechanical and tribotechnical characteristics of ones with a hybrid polymeric “UHMWPE + polytetrafluoroethylene (PTFE)” matrix under dry sliding friction were investigated. It is shown that the wear rate of micro-and nanocomposites based on the “UHMWPE + 10 wt.% PTFE” matrix under dry sliding friction is reduced by 10-30 %. Mechanical characteristics are not changed significantly in the nanocomposites, while in the microcomposites they are reduced substantially. By means of scanning electron microscopy, differential scanning calorimetry and optical microscopy the permolecular structure, degree of crystallinity and surface topography of micro-and nanocomposites based on the hybrid matrix were investigated. The mechanisms of wear of “UHMWPE-PTFE” composites under dry sliding friction are discussed.

Tribotechnical Properties of HA Nanocomposite Based on UHMWPE under Dry Sliding and Lubrication

The tribotechnical properties of hydroxyapatite (HA) nanocomposite based on ultra-high molecular weight polyethylene (UHMWPE) under dry sliding and lubrication of distilled water and plasma blood was investigated with block-on-ring. It was shown that modification of UHMWPE by HA nanoparticles within range of 0.1–0.5 wt.% results in decrease of wear intensity at dry sliding up to 3 times. The under lubrication, wear intensity of pure UHMWPE and nanocomposite are deceased up to 50–70% as compared with under dry sliding. Permolecular structure of pure UHMWPE and nanocomposite are spherulitic structure, which nanoparticle does not alter the nature of the permolecular structure, and homogeneously dispersed in the UHMWPE matrix.

Tribotechnical Properties of UHMWPE Based Composite Filled with HA Microparticles under Dry Sliding and Lubrication

The tribotechnical properties of ultra-high molecular weight polyethylene (UHMWPE) based composite filled with hydroxyapatite (HA) microparticles under dry sliding and lubrication of distilled water and plasma blood wear investigated with block-on-ring. It was shown that modification of UHMWPE by HA microparticles of 20 wt.% results in decrease of wear intensity at dry sliding up to 4 times. The under lubrication, wear intensity of pure UHMWPE and microcomposite are deceased up to 50–70% as compared with under dry sliding. Permolecular structure of pure UHMWPE and microcomposite are spherulitic structure and the HA microparticles were dispersed in the UHMWPE matrix.

Mechanical and Tribotechnical Characteristics of Nanocomposites Based on Mixture of Ultrahigh Molecular Weight Polyethylene and Polypropylene

The aim of the study is to design wear-resistant and extrudable polymeric composites based on mixture of UHMWPE+PP with increased tribotechnical characteristics for the wide application in friction units of machine parts and mechanisms as well as using the polymeric resin developed for obtaining nanocomposites. Adding of block copolymer PP-b LLDPE to UHMWPE is motivated by the necessity to increase the adhesion between the incompatible polymeric components of the mixture. It is shown that wear intensity of the polymer-polymeric composites UHMWPE+n wt.% PP-b-LLDPE is reduced at filling UHMWPE by the block copolymer. In doing so, an important technological characteristic of UHMWPE specific extrusion pressure (proportional to the melt flow index) is improved (is lowered). Nanocomposites on the basis of the given matrix have shown wear resistance of 3-4 times higher in contrast with pure UHMWPE. Permolecular structure and wear track surfaces of nanocomposites on the basis of polymer-polymeric matrix (UHMWPE+10 wt.% PP-b-LLDPE) were investigated. The mechanism of the wear of nanocomposites is discussed.