Comparison of Exfoliated Graphite Nanoplatelets (xGnP) and CNTs for Reinforcement of EVA Nanocomposites Fabricated by Solution Compounding Method and Three Screw Rotating Systems

Exfoliated graphite nanoplatelet (xGnP (TM)) and carbon nanotube (CNT)-reinforced ethylene vinyl acetate (EVA) nanocomposites have been fabricated by three screw rotating systems: co-, counter- and modified-co-rotating. The highest tensile strength and modulus were shown by the composites, both xGnP- and CNT-loaded, made by counter- rotating. The counter- rotating process produced better dispersion than the other two as found in morphology studies by environmental scanning electron microscopy (ESEM). However, the rotating system did not affect the electrical conductivity. The percolation threshold of the xGnP-EVA nanocomposites formed by solution mixing and injection molding was between 14-16 wt%, due to the advantageous effect of sheets with higher aspect ratios compared with spherical or elliptical fillers in forming conducting networks in the polymer matrix. Although CNT-EVA was electrically conductive with only 5 wt% CNT loading, we recommend xGnP as a more suitable additive material for polymer composites. xGnP greatly increased the thermal stability of xGnP- EVA composites to be applied as adhesives, films and cables. (C) Koninklijke Brill NV, Leiden, 2009