The mechanical properties and the fracture toughness of polymers can be increased by adding silica nanoparticles. This increase is mainly caused by the development of localized shear bands, initiated by the stress concentrations due to the silica particles. Other mechanisms responsible for the observed toughening are debonding of the particles and void growth in the matrix material. The particular mechanisms depend strongly on the structure and chemistry of the polymers and will be analysed for two classes of polymer-silica composites, with highly crosslinked thermosets or with biodegradable nestled fibres (cellulose, aramid) as matrix materials.

The aim of the project is to study the influence of different mesoscopic parameters, as particle volume fraction, on the macroscopic fracture properties of nanoparticle reinforced polymers.