This study investigates the impact of a binary filler on the physicomechanical and tribological properties, as well as structure, of polymeric composite materials based on ultra-high-molecular-weight polyethylene. The organic modifier—2-mercaptobenzothiazole and wollastonite particles synthesized from two different systems (modeled and derived from waste) were used as the binary filler. The synthesis of wollastonite was carried out in the complex model system (CaSO4·2H2O–SiO2·nH2O–KOH–H2O) and from technogenic waste (borogypsum). It was demonstrated that the introduction of the binary filler made it possible to obtain an optimal combination of mechanical and tribological properties. It was found that during the wear of polymeric composite materials loaded with organic fillers, the fillers migrate to the friction surface, providing a shield against abrasive wear of the steel counterface. Due to the modification of ultra-high-molecular-weight polyethylene by 2-mercaptobenzothiazole, the interdiffusion of polymeric matrix macromolecules and interphase coupling with wollastonite particles improve. The 2-mercaptobenzothiazole organic compound used as the filler facilitates the relaxation processes within the composite under external loads.
The paper presents the results of studying the effect of borpolymer (BP) on the mechanical properties, structure, and thermodynamic parameters of ultra-high molecular weight polyethylene (UHMWPE). Changes in the mechanical characteristics of polymer composites material (PCM) are confirmed and complemented by structural studies. X-ray crystallography (XRC), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and infrared spectroscopy (IR) were used to study the melting point, morphology and composition of the filler, which corresponds to the composition and data of the certificate of the synthesized BP. Tensile and compressive mechanical tests were carried out in accordance with generally accepted standards (ASTM). It is shown that BP is an effective modifier for UHMWPE, contributing to a significant increase in the deformation and strength characteristics of the composite: tensile strength of PCM by 56%, elongation at break by 28% and compressive strength at 10% strain by 65% compared to the initial UHMWPE, due to intensive changes in the supramolecular structure of the matrix. Structural studies revealed that BP does not chemically interact with UHMWPE, but due to its high adhesion to the polymer, it acts as a reinforcing filler. SEM was used to establish the formation of a spherulite supramolecular structure of polymer composites.
Frost-resistant rubbers retain their highly elastic properties over a wide temperature range. They are used in various friction units (e.g., seals), but their high friction coefficient and low wear resistance lead to the need for frequent replacement. In this paper, we propose applying thin (several hundred microns) UHMWPE coatings to formed rubber rings. The application technology depends on the required coating thickness. Friction tests of the coatings and pure UHMWPE were performed using the ball-on-disk (unidirectional sliding) scheme for various loads and velocities. In the experiments, the friction coefficients and temperatures near the contact area were determined. Friction tracks were studied using microscopy methods. The sliding contact of the ball and the two-layer material was modeled to obtain the dependences of the deformation component of friction on the sliding velocity for coatings of different thicknesses. UHMWPE is sensitive to frictional heating, so the thermal problem of determining the temperature in the contact area was also solved. It is shown that the minimum friction coefficient occurs for coatings with a thickness of 600 μm. At the same time, in the case of the 300 μm coating, the surface of the friction track is practically no different from the initial one. Thus, the studied combination of polymers provides antifrictional properties and wear resistance to the surface layer while maintaining the damping properties of rubber.
The aim of the study is the development of two-layer materials based on ultra-high-molecular-weight polyethylene (UHMWPE) and isoprene rubber (IR) depending on the vulcanization accelerators (2-mercaptobenzothiazole (MBT), diphenylguanidine (DPG), and tetramethylthiuram disulfide (TMTD)). The article presents the study of the influence of these accelerators on the properties and structure of UHMWPE. It is shown that the use of accelerators to modify UHMWPE leads to an increase in tensile strength of 28–53%, a relative elongation at fracture of 7–23%, and wear resistance of three times compared to the original UHMWPE. It has been determined that the introduction of selected vulcanization accelerators into UHMWPE leads to an increase in adhesion between the polymer and rubber. The study of the interfacial boundary of a two-layer material with scanning electron microscopy (SEM) and infrared spectroscopy (FTIR) showed that the structure is characterized by the presence of UHMWPE fibrils localized in the rubber material due to mechanical adhesion.
Advancements in industrial machinery and manufacturing equipment require more reliable and efficient polymer tribo-systems which operate in conditions associated with increasing machine speeds and a lack of cooling oil. The goal of the current research is to improve the tribological properties of elastomeric composites by adding a solid lubricant filler in the form of ultrafine polytetrafluoroethylene (PTFE) with the chemical formula [C2F4]n and recycled polytetrafluoroethylene (r-PTFE) powders. PTFE waste is recycled mechanically by abrasion. The elastomeric composites are prepared by mixing a nitrile butadiene rubber with a phenol-formaldehyde resin and PTFE powders in an extruder followed by rolling. The deformation-strength and tribological tests of r-PTFE elastomeric composites are conducted in comparison with the ultrafine PTFE composites. The latter is based on products of waste fluoropolymer processing using a radiation method. The deformation-strength test shows that the introduction of ultrafine PTFE and r-PTFE powder to the composite leads to a decrease in strength and elongation at break, which is associated with the poor compatibility of additives and the elastomeric matrix. The friction test indicates a decrease in the coefficient of friction of the composite material. It is determined that the 15 wt.% filler added in the elastomeric matrix leads to a reduction in the wear rate by 20%. The results obtained show the possibility of using ultrafine PTFE powder and r-PTFE for creating elastomeric composites with increased tribological properties. These research results are beneficial for rubber products used in many industries, mainly in mechanical engineering.
The paper presents a method of applying a protective coating from ultrahigh molecular weight polyethylene to rubber products. A distinctive feature of the presented method is the prevulcanization of a rubber compound in order to form it into the desired shape and remove an excess rubber material. The application of an ultrahigh molecular weight polyethylene powder to the prepared surface ensures a uniform coating thickness. To achieve an optimal combination of rubber properties, we study how the scorch time affects its physical and mechanical properties, hardness, corrosion, abrasion and thermal resistance. We find the scorch time range in which a spatial elastomeric network forms that influences the penetration of ultrahigh molecular weight polyethylene into butadiene-nitrile rubber.