Reducing friction with Al2O3/SiO2-nanoparticles in NBR

Friction is a phenomenon that is sometimes desired and sometimes to be avoided. In the past, material development grants have not focused on this task. In this article, we present a new and alternative method of reducing elastomer friction when sliding on different kinds of substrates by inducing hard alumina/silica nanostructures on the elastomer surface. The formation of Al2O3/SiO2 nanostructures is based on an in situ sol–gel process of a dispersion of spherical aluminum oxide nanoparticles in a silica liquid precursor polymer – hyperbranched polyalkoxysiloxane (PAOS) – in an elastomer mixture. The influence of variable amounts of Al2O3/PAOS dispersion, variable amounts of carbon black fillers and annealing time on the friction coefficient is studied for a large velocity range. Experiments were conducted with and without lubricant and discussed with regard to material and surface properties of the samples. It is found that sufficient PAOS concentrations significantly decrease friction for all systems and prevent stick-slip phenomena.

► PAOS builds Al2O3/SiO2 nanostructures in NBR rubber in situ sol–gel process.
► Friction is reduced for high amounts of PAOS fillings on various substrates.
► Stick-slip can be prevented.
► Material and surface properties are changed by presence of PAOS.