Multifunctional Nanocomposites Made of Polypropylene Reinforced with Exfoliated Graphite Nanoplatelets (xGnP)
K. Kalaitzidou, H. Fukushima and L.T. Drzal
Michigan State University, US
polypropylene, graphite nanoplatelet, nanocomposite
Polypropylene is one of the most widely used polymers. It is an attractive material because of its combination of mechanical properties, ease of processing and low cost. This research explores modification of polypropylene through addition of exfoliated graphite nanoplatelets (xGnP) a new multifunctional material developed at MSU, as an additive capable of producing new and desirable multifunctional properties in polypropylene. The main fabrication method used to produce PP-xGnP nanocomposites is melt mixing and injection molding. The exfoliated graphite nanoplatelet (xGnP) dispersion and morphology within the PP is characterized using TEM while the Environmental SEM is used to quantify the morphology and the fracture surface of the nanocomposites. The mechanical (flexural strength and modulus, tensile modulus and impact strength), thermal (coefficient of thermal expansion and thermal conductivity), barrier (permeation of O2), viscoelastic and electrical properties of (xGnP)-PP nanocomposites are also determined and compared to composites made using other carbon-based electrically conductive fillers and nanoclays. Processing limitations with melt of solvent processing were overcome with a new cost and time effective and environmentally friendly compounding method that improves the dispersion of (xGnP) in the polymer matrix and results in composites with lower percolation threshold. The addition of xGnP has a beneficial effect on the physical properties i.e., viscosity, crystallization and melting behavior of these polyolefin composites. An explanation of how the addition of xGnP alters the structure-processing-property relationships of the PP-xGnP nanocomposites will be presented along with how these properties are related to the xGnP’s microstructure, the state of dispersion, the aspect ratio, orientation and the interactions between xGnP and the polymer chains.
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Nanotech 2006 Conference Program Abstract