Abstract
It has been demonstrated in recent years that the tribological performance of polymer-based composites can be greatly improved by incorporating, besides such classical tribofillers as short carbon fibers and lubricating graphite flakes, additional ceramic nanoparticles into the polymeric matrix. However, due to the large surface area and high adhesion forces, nanoparticles exist not as separate particles, but as their agglomerates. To achieve the desired improvements, it is necessary to split up these agglomerations and to distribute them as single particles in the polymeric matrix.
In the present paper, this is demonstrated for two different thermoplastics used frequently as matrices for polymeric tribomaterials (polyamide 66, PA66, and polyetheretherketone, PEEK). Processing by twin-screw extrusion allowed us to incorporate titanium dioxide (TiO2) nanoparticles of different size (15 and 300 nm). The production of a highly filled masterbatch and its multiple extrusion and dilution resulted in a very good deagglomeration, which improved its performance considerably.
In regard to particle size, the 15-nm particles showed a significantly greater improvement in the mechanical properties of polymer-based composites than the 300-nm ones. Enhancements in the stiffness, strength, and toughness could be achieved in many cases. The scanning electron microscopy confirmed these results.
The final set of results obtained illustrates how the nanoparticles improve the tribological behavior of PA66 and PEEK compounds used in various industrial applications.