Structure and properties of metal-free conductive tracks on polyethylene/multiwalled carbon nanotube composites as obtained by laser stimulated percolation

The fabrication and characterization of conductive tracks by laser irradiation on non- conductive multiwalled carbon nanotube/polyethylene (MWCNT/HDPE) composites is reported. Along the irradiated paths the percolation of MWCNTs is occurring, as demonstrated by field emission scanning electron and atomic force microscopies. An increment of tracks conductivity of several orders of magnitude is documented by single pass Kelvin probe force and current sensing atomic force microscopies, together with electrical measurements. The structure of conductive paths has been estimated by secondary electron charge contrast imaging. The investigation has been developed from basic characterization up to industrial scale manufacturing. The method is fast, flexible and innovative, because: i) highly adherent tracks of any selected pattern on a low cost material can be obtained, ii) the tracks are metal-free, a fact rendering the composite fully recyclable and iii) the irradiated materials have application for electrical signals transport; iv) the tracks are also characterized by piezoresistive properties so allowing their employment as pressure sensors.