The potential of exfoliated graphite nanoplatelets, (graphene sheets ~10nm thickness, ~lum diameter), a new material developed in our lab, is explored as a multifunctional nanoreinforcement for polymers i.e., polypropylene. Exfoliated graphite nanoplatelet (xGnP)-polypropylene (PP) nanocomposites are fabricated by two-step process, compounding and molding (injection or compression). Two approaches are employed for the compounding: (i) solution method and (ii) melt mixing. Results include mechanical properties such as flexural strength, modulus of elasticity, and impact strength and thermal properties i.e., coefficient of thermal expansion and thermal conductivity. In addition, the electrical conductivity and the percolation threshold of the xGnP-PP nanocomposites are determined as a function of the xGnP's aspect ratio fabrication method and processing conditions used. Furthermore, the xGnP-PP nanocomposites are compared to composites made using other carbon-based electrically conductive fillers such as carbon black (CB), vapor grown carbon fibers (VGCF) and polyacrylonitrile based carbon fibers (PAN). Finally, a crystallinity study performed using differential scanning calorimetry (DSC), X-ray diffraction, (XRD), and optical microscopy indicated that xGnP acts as a nucleating agent for PP by increasing the crystallization temperature, and promotes the less preferable (3 crystal form which is responsible for the observed increase of impact strength at low xGnP loadings. Addition of xGnP had no effect on the overall degree of crystallinity.
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