Nanoindentation and wear behavior of thermally stable biocompatible polysulfone–alumina nanocomposites
Besides improving mechanical performance, wear resistance is the first prerequisite for a dental material to be accepted by both dentists and patients, and therefore good wear behavior may contribute to the longevity and durable aesthetics of a dental material such as brackets or implants. In this work we have investigated the wear and mechanical behavior, along with the thermal stability, of polysulfone/modified alumina. γ-Alumina nanoparticles have been modified with polysulfone (PSU) chains of two different molecular weights. The modification leads to an enhanced homogeneous dispersion, as was confirmed using TEM-image analysis, and enhanced mechanical and wear behavior when compared with a PSU/alumina nanocomposite. Nanoindentation measurements confirmed that the elastic modulus values were enhanced when modified nanoparticles were used to prepare nanocomposites. Abrasive wear analysis revealed that the wear volume loss was decreased when the nanoparticles were modified. The PSU chains grafted to alumina promoted enhanced particle dispersion, which at the same time induced protection in the polysulfone matrix against wearing off. The results showed a clear tendency for increased strength and wear resistance, without sacrificing transparency. Regarding the thermal stability of the materials prepared, the results showed similar thermal stabilities for both neat PSU and modified particle nanocomposites up to a certain temperature (i.e., ∼550 °C), and after this temperature these nanocomposites displayed a higher thermal stability than neat PSU.