Influences of carbon nanotubes/polycarbonate composite on enhanced local laser marking properties of polypropylene

The influences of carbon nanotubes/polycarbonate (CNTs/PC) on the enhanced local laser marking properties of polypropylene (PP) are studied. PC is first coated on the surface of CNTs to prepare composite powder, and then the composite powder is added to PP at a very low content (10 ppm). A low-energy near-infrared laser (1064 nm) is used to irradiate the surface of the composite to create patterns. Visual and microscopic analyses of the PP-doped CNTs/PC composite after laser marking show clear black pattern, depending on the CNTs content, PC ratio, and laser current. The changes in surface morphology and structure of composite materials are further analyzed by Raman spectroscopy and scanning electron microscopy. Tests show that the black marking is composed of amorphous carbon materials induced by laser. Furthermore, a mechanism for the enhanced local laser marking of the PP-doped CNTs/PC composite is proposed. CNTs with excellent photothermal conversion effect and PC with active carbonization function synergistically improve the responsiveness of PP to laser.