(395g) Impact Resistance and Adhesive Properties of a Functionally Graded Polymer Composite Interlayer

There is growing interest in lightweight materials with high impact resistance for various applications. In the development of these materials, researchers have started to explore polymer composites containing very low concentrations of ceramics and/or metals with at least one dimension ranging from nanometers to a few microns. In this research, we attempt to synthesize an interlayer nanocomposite polymer which provides a gradual transition of elastic modulus between two laminates of dissimilar modulus.  This is expected to minimize the stress concentration gradient at the interlayer boundaries and improve impact resistance.

Formulation of polyurea and polyurethane from disocynate and diamine and/or polyol prepolymers was investigated, and promising candidates were mixed with nanoparticles, nanowhiskers or nanofibers of alumina or silicon carbide at different loading levels and size/loading distributions. These nanoparticle/nanofiber resin systems were designed to serve as a bonding layer between materials of dissimilar modulus (such as ceramics, metals and polymers) while creating a functionally graded composite with minimal interfacial stress and high energy absorbing properties. We will present details of the synthesis of the polyurethane/polyurea resins and the preparation of the nanocomposite interlayer material; characterization of the nanocomposite layer and interface regions; and results from mechanical property testing.