In the present study, the tribological behavior of polytetrafluoroethylene (PTFE) composites filled with natural layered silicates (LS) was investigated. The change in the morphology of the friction surface of composites depending on the content and chemical composition of layered silicates has been shown. The friction surface of PTFE composites with layered silicates was investigated by scanning electron microscopy (SEM). The formation on the friction surface of a special layer with a structure different from the bulk of the polymer, which is formed from particles of fillers and wear products, has been established. The thickness of this layer is independent of the content of layered silicates in the polymer. It was indicated that wear debris of PTFE composites was assembled during friction and uniformly cover the friction surface layer by layer, thereby forming a protective layer.

The tribotechnical characteristics of polymer composites based on PTFE and layer silicates (serpentinite) were studied, depending on the test duration time. It was indicated that adding a serpentinite and magnesium spinel increased the wear resistance of the composite by up to 480 times compared to the original PTFE. It was found that particles of fillers and PTFE promote formation of a secondary structure on the friction surface, helping reduce the material wear process. The method of infrared (IR) spectroscopy and EDS showed that tribochemical reactions take place on the friction surface of composites.

The paper presents the results of a study of synthetic wollastonite from boric acid production waste (borogypsum) on the physical, mechanical and tribological properties of polymer composite materials based on polytetrafluoroethylene. Wollastonite was synthesized from borogypsum by its hydrothermal treatment in alkaline medium and subsequent calcination of the obtained precipitate at 900-1000 °C for 1 h. The product with a specific surface area of 1.4 m2/g and a density of 3.06 g/cm3 obtained under the above regimes is characterized by the presence of wollastonite of triclinic modification and the presence of CaSO4 anhydrite. The wollastonite particles are needle-shaped with a needle diameter of ~100 nm. Needle-shaped wollastonite particles are shown to be interconnected and form conglomerates and agglomerates ranging in size from 10 to 70 μm. Particle agglomerates are characterized by a wide unimodal distribution of pores with a maximum of 3.78 nm with conical and slit-like shapes. It was found that the use of wollastonite results in increased wear resistance of polymer composites based on PTFE. Composites filled with 10 and 20 wt.% of wollastonite are characterized by a 700-fold decrease in the rate of mass wear relative to the initial polymer. Physical and mechanical studies of PCM show that the introduction of wollastonite increases compressive strength and modulus of elasticity. However, a decrease in strain-strength parameters was observed. Scanning electron microscopy shows the formation of secondary structures on friction surfaces, which plays a role in the adaptation of the composite to wear. The method of IR spectroscopy of friction surfaces registered the appearance of new peaks corresponding to hydroxyl, carbonyl and carboxyl compounds. This indicates a certain contribution of wollastonite particles to tribochemical processes. For citation: Danilova S.N., Tarasova P.N., Yarusova S.B., Kapitonova Yu.V., Osipova V.N., Okhlopkova A.A., Gordienko P.S. Evaluation of the influence of wollastonite from technogenic waste on the properties of a polymer composite based on polytetrafluoroethylene. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 12. P. 102-112. DOI: 10.6060/ivkkt.20246712.7064.

The use of ultrasound (US) stimulated the production of composites with an improved complex of properties. It was found that ultrasonic treatment helps to reduce the coefficient of friction and improve the wear resistance of composites while maintaining deformation parameters at the level of the initial polymer. It is noted that the influence of ultrasonic vibrations on the deformation-strength characteristics of composites is due to the crystallographic properties of phlogopite and magnesium spinel (MS) used as modifiers of PTFE.

In this research, the results of studies on the influence of natural mica and mixed magnesium aluminium oxide (MAO) on the structure and properties of polytetrafluoroethylene (PTFE) are presented. Mechanical and tribological tests were conducted on PTFE-based composite samples. It was found that the addition of mica increases the relative elongation by 43 % and raises the wear resistance by 277 times compared to the initial polymer. The coefficient of friction is from 0.24 to 0.29. At the supplementary addition of mixed magnesium aluminium oxide, the wear resistance increases by up to 312 times and the coefficient of friction decreases by 38 %. It is shown that, with the addition of mica alone, the relative elongation improves and that with the additional introduction of mixed magnesium aluminium oxide, the wear resistance of the material increases. The maximum wear resistance is shown by the composite containing 5 wt. % mica and 1 wt. % MAO. Investigations of the worn surface of composites have shown that the decrease in mass loss of composites is associated with the formation of a wear resistant surface formed during the asperity interaction. It is revealed that the formation of a wear resistant structure on the material's contact surface is caused by the formation of a secondary layer and chemical reactions that occur during interaction.