1 POST-PRINT Submitted, accepted and published in Materials Chemistry and Physics 137 859-865 (2013); DOI: 10.1016/j.matchemphys.2012.10.026 Preparation of Polymer Composites using Nanostructured Carbon Produced at Large Scale by Catalytic Decomposition of Methane I. Suelves a∗ , R. Utrilla, D. Torres, S. de Llobet, J.L. Pinilla, M.J. Lázaro, R.Moliner a Instituto de Carboquímica, CSIC. Miguel Luesma 4, 50018 Zaragoza, Spain Abstract Polymer-based composites have been prepared using different concentrations of nanostructured carbons (NCs), produced by catalytic decomposition of methane (CDM). Four carbonaceous nanostructures were produced using different catalysts (with Ni and Fe as active phases), in a rotary bed reactor capable of producing up to 20 g of carbon per hour. The effect of nanostructured carbon on the thermal and electrical behaviour of epoxy-based composites is studied. An increase in the thermal stability and the decrease of electrical resistivity were observed for the composites at carbon contents as low as 1 wt%. The highest reduction of the electrical resistivity was obtained using multi-walled carbon nanotubes (MWCNTs) obtained with the Fe based catalysts. This effect could be related with the high degree of structural order of these materials. The results were compared with those obtained using a commercial carbon nanofibre, showing that the use of carbon nanostructures from CDM can be a valid alternative to the commercial nanofibres. ∗ Corresponding author: fax: +34 976 73 3318, e-mail address: isuelves@icb.csic.es