Effect of nitrogen and oxygen doped carbon nanotubes on flammability of epoxy nanocomposites

To overcome the flammability of epoxy resins, novel nitrogen (CNₓ) and oxygen (COₓ) doped CNT were synthesized via CVD method and epoxy nanocomposites at 2 wt.%. constant loading were prepared by three roll milling and cured. The structures of the nanotubes were confirmed by XRD, XPS, SEM and Raman and it was found a very high aspect ratio especially for COₓ. Thermal degradation as well as glass transition temperatures and elastic moduli were measured by TGA, DSC and DMTA. The flammability of epoxy nanocomposites was studied by microscale combustion calorimetry (MCC) and limiting oxygen index (LOI) determination. Results showed that the fire retardant properties of nanocomposites improved significantly specially for COₓ, which presented a very high LOI (35%) and a homogeneous and uniform surface after burning. This effect was tentatively attributed to the very high aspect ratio of COₓ tubes.Authors wish to acknowledge financial support from Spanish Ministerio de Economía y Competitividad under grant MAT2014-57557-R. Authors also wish to thank Dr. Sofía M. Vega-Díaz for her invaluable help with XPS interpretatio