Preparation and properties of polypropylene-carbon nanotubes nanocomposites for application in bipolar plates

Polymer electrolyte membrane fuel cells (PEMFCs) have the potential to play a major role as energy sources for transportation and portable applications because they feature high power density at relatively low operating temperatures. Bipolar plates are a key component of PEMFCs in terms of cost and weight. To date, many different materials for bipolar plates have been investigated and an alternative solution consists in carbon nanotubes (CNTs)-filled polymer nanocomposites which combine the good processability, high corrosion resistance and good mechanical properties of polymers with the excellent electrical and other functional properties of the CNTs. However, a preferential distribution of well dispersed CNTs forming conductive 3D networks is required to successfully exploit their potential. In this work, polypropylene (PP)-multi-walled CNTs (MWCNTs) nanocomposites have been prepared by melt-blending using different loadings (1, 2 and 5 wt.%) of MWCNTs and processing conditions. The microstructure and properties of these nanocomposites have been characterized on molded plates of 1.5 mm thickness. The state of dispersion of the MWCNTs in the polymer matrix is investigated by SEM and optical confocal microscopy and the electrical properties of the nanocomposites are measured in order to find the electrical percolation threshold.