EFFETTI DI NANOTUBI SULLA RESISTENZA A FATICA DI BIOCOMPOSITI A FIBRE CORTE RANDOM

In order to comply with the recent regulations in terms of environmental protection, biocomposites reinforced with natural fibers are increasingly used in the automotive sector, for the replacement of synthetic materials in semi-structural applications as panels, filling material, coating, dashboards, etc. The good mechanical performances of these materials, mixed with low weight and low cost, also make it possible to minimize the weight of the vehicle, and therefore consumption, but also the relative production costs. These are composites with random short fiber appreciated for their good stiffness, generally well above that of the matrix alone. Due to the peculiar "transverse" damage phenomena, often also influenced by debonding and pull-out phenomena related to the limited fiber-matrix adhesion, the mechanical, static and fatigue resistance of these materials is instead generally comparable to that of the matrix alone. This prevents their use in more mechanically demanding applications. For this reason, several chemical treatments on the fibers have been proposed in the literature by various authors, although still not fully satisfactory results have been obtained in terms of improving resistance. Taking into account the positive effects of the nanotubes on the fatigue resistance of structural polymeric adhesives and polymer matrix composites reinforced with synthetic fibers, in this work the effects of nanotubes on the fatigue resistance of biocomposites reinforced with agave fibers are analyzed, the fibers are obtained with a special compression molding process. The tests carried out on green epoxy matrix biocomposites in which nanotubes with different concentrations in volume were previously dispersed, showed that the static strenght is significantly influenced by the presence of nanotubes, although more appreciable improvements are found in the fatigue performance.