Influence of filler dispersion and interfacial resistance on thermal conductivity of polypropylene/carbon nanotubes systems

Carbon nanotubes effectiveness, as thermally conductor, in polymer/CNTs nanocomposites, is mainly related to various key aspects as dispersion, matrix/CNT interfacial resistance and inter-CNT contact resistance. Features of raw materials and processing parameters for the realization of nanotube/polymer composites, can simultaneously affect these critical issues, also in adverse way. In this contribution, polypropylene based-composites, containing multi walled carbon nanotubes (MWNTs), are prepared by melt-blending and then characterized prevalently in term of thermal transport behavior, choosing different matrix grades, filler functionalization and process conditions. In more details, two commercial polypropylene (PP) grades with different melt flow rates are considered as matrices and three kind of MWNTs with the same aspect ratio, one neat and two chemically modified with carboxyl -COOH and amino -NH2 groups, respectively, are used as fillers. The presence of a compatibilizer, as maleic anhydride grafted polypropylene (Ma-g-PP), and the use of various processing conditions as temperature, time, screw speed, pressure, filler drying and so on, are taken into account in order to optimize the thermal conductivity enhancement of PP/MWNTs compounds.