Ultrasonic Dispersion of Inorganic Nanoparticles in Epoxy Resin and Mechanical Properties of the Resulting Nanocomposites

摘要

Research of the past few years showed that the insertion of nanoparticles into a polymer matrix may lead to completely new material properties compared to conventional composites reinforced by microscale fillers. In particular, a simultaneous enhancement of toughness and stiffness can already be achieved for relatively low particle contents. The present study focuses on the ultrasonic dispersion of titanium dioxide and barium sulfate nanoparticles in a DGEBA epoxy resin. A systematic variation of sonication parameters, like ultrasonic amplitude and dispersion time was accomplished to determine the optimum processing parameters. Therefore, the development of particle size in dependence on ultrasonic process parameters was analyzed. The aim is to achieve a separation of agglomerates and a homogeneous distribution of nanoparticles within the thermosetting matrix without degrading the molecular structure of the epoxy resin. Subsequently, nanocomposite samples were manufactured to determine the mechanical properties' profile. Simultaneous improvement of the elastic modulus and fracture toughness of the materials was observed. Scanning electron microscope (SEM) pictures were performed on the samples' fracture surfaces in order to examine reinforcing mechanisms of nanoparticles leading to improved material properties. These pictures revealed a change of the fracture behavior from a relatively brittle fracture for neat polymer to a more ductile behavior for nanocomposites.