The present invention relates to a masterbatch for use in a process of preparing a composite material comprising a blend of a first semi-crystalline polymer with at least 5 wt % carbon nanotubes. Good dispersion of the carbon nanotube is obtained within the masterbatch and evidenced by the blending of the masterbatch with a second semi-crystalline polymer miscible with the first one in respective proportions to obtain a composite material containing about 1 wt % of carbon nanotubes wherein said composite material yields an agglomerate area fraction U % lower than 2 and a surface resistivity lower than 105 ohm/sq.