Carbon nanotubes in near-infrared laser irradiation for locally controllable surface foaming of polypropylene

In recent years, foam materials have attracted people's attention in many fields. This study reveals the one- step preparation of polypropylene (PP) foam material with very low carbon nanotubes (CNTs) content via laser irradiation technology. A low-energy near-infrared (1064 nm) laser beam is used to scan the laser-sensitive PP/CNTs composite prepared in the air. The controllable instantaneous thermal energy generated by laser irradiation decomposes CNTs and PP, and forms a foaming layer in situ on the surface of the composite material. CNTs content, laser power and laser scanning rate are key parameters for controlling laser-induced foaming. The results show that the rich carbonized structure induced by the laser envelops the gas generated by thermal degradation to form a porous structure, and form a 3D white pattern with the naked eye. This study can provide a positive reference for directly writing 3D foamed structures on the surface of composite materials on a large scale through a simple and efficient one-step laser irradiation method. (author)