AFM Measurements of Polyimide/Silicon Nitride Nanocomposite Interphase

According to recent studies on electrical insulation systems, it was demonstrated that the nanocomposite (NC) organic/inorganic hybrid materials assure a distinct improvement of their high-temperature functioning and allow these systems to strengthen their dielectric properties. Recently, it was shown that some modifications of the electrical properties such as permittivity, dielectric breakdown, partial discharges resistance, or lifetime were often awarded to the properties of what it is called the interphase. This interphase represents the interaction zone between the matrix and nanoparticles and plays very often a leading part in the definition of the material macroscopic properties. However, the role of the interphase remains theoretical and a few experimental results exist to describe this phenomenon. In this paper, atomic force microscopy (AFM) is used to make at the same time qualitative and quantitative measurements of these interaction zones within polyimide/silicon nitride NC. For example, the peak force quantitative nano mechanical AFM mode reveals the presence of the interphase by measuring mechanical properties (Young modulus, deformation, and adhesion). As a result, this new and original study on the interphase measurement confronts experimental results with theoretical models.