Thermoplastic/Thermosetting Polymer Blends Reinforced with Tungsten Disulfide Nanostructures as Promising Wear and Cavitation-Resistant Coatings

Unique properties of multi-layer WS2 nanostructures, including their high mechanical strength, excellent lubricating abilities, chemical inertness, and thermal stability, make them highly promising as reinforcement of polymer composites for applications in demanding environments such as aerospace, automotive, marine applications, protective equipment, and industrial machinery. WS2, like graphite and MoS2, possesses a layered structure that enables it to function as a solid lubricant, thereby reducing friction and improving the durability of the materials into which it is integrated. This feature might be specifically beneficial in coatings and protective layers. This research investigates poly(vinyl butyral)/epoxy layers reinforced with tungsten disulfide (WS2) nanostructures, a novel class of coatings engineered for enhanced thermo-mechanical, wear, and cavitation resistance. Poly(vinyl butyral), PVB –a thermoplastic elastomer, and epoxy resin – a thermosetting polymer, combined together may provide a tough but flexible matrix that can absorb impact energy from cavitation bubbles. The hybrid polymer matrix (PVB/epoxy) offers resistance to chemical degradation, moisture, and corrosion. Epoxy ensures strong adhesion to the substrate, while PVB improves elasticity. WS2 nanoparticles further enhance this property by reinforcing the matrix and reducing crack propagation. PVB/epoxy composite coatings incorporating WS2 nanostructures were synthesized and evaluated for their thermo-mechanical and cavitation resistance properties. The coatings were prepared using a solution blending technique. PVB and epoxy resin in a ratio of 5:95 were dissolved in the appropriate solvent – ethanol, and mixed to achieve a homogeneous solution. WS2 was ultrasonically dispersed in ethanol before the polymers were added to ensure uniform distribution of the nanostructures in the matrix. The resulting mixture was then cast into Teflon molds to form thick coatings, which were cured under controlled conditions to optimize their mechanical properties. Morphological and structural analyses, including scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), were conducted to assess the dispersion of WS₂ within the polymer matrix. FTIR analysis was carried out to estimate the interaction of the reinforcement with the matrix. The material's mechanical resistance was examined through microhardness measurement and the cavitation wear was assessed through ultrasonic cavitation tests, followed by damage analysis. The thermal stability of the coatings was examined using differential scanning calorimetry. The findings suggest that PVB/epoxy-WS₂ layers are promising as coatings for extending the lifespan of components exposed to high friction and cavitation environments, with potential applications in advanced composite materials, in marine and hydraulic systems, and as protection against cavitation damage in propellers, pumps, and turbines, and in general, parts subjected to high friction and erosion. Further optimization of nanostructure dispersion and optimization of desirable concentrations of WS2 could further enhance the performance of these coatings.