Effect of water conditioning on the fracture behavior of PA12 composites processed by selective laser sintering

This study aims to elucidate the combined effects of reinforcing particles and water on PA12 processed by selective laser sintering (SLS). PA12 is one of the toughest polyamides. However, PA12 processed by SLS is rather brittle due to the presence of voids and the relative low molecular weight of the polymers used in SLS. It is demonstrated that humidity impoverishes the mechanical properties of neat PA12, including ductility and toughness. A ductile/brittle transition was detected, which was attributed to the competition between the plasticizing effect and the hydrolization of PA12 molecules plus the increase in crystallinity which counteracted this mechanism. It has been found that addition of hard particles, such as glass spheres and ceramic fibers, prevents the ductile/brittle transition by water conditioning at high temperature to happen.