Increasing the interfacial adhesion in poly(methyl methacrylate)/carbon fibre composites by laser surface treatment

The impact strength of poly(methyl methacrylate)/carbon (long) fibre composites for denture prosthesis applications was improved by fibre surface treatment. The carbon fibre surfaces were modified by Nd:YAG laser irradiation at 1064 nm wavelength. Laser light intensity was adjusted at 100 mJ per pulse that only changed the fibre surface roughness and did not lead to fibre rupture, as verified by scanning electron microscopy. Increased surface roughness of the fibres improved the adhesion of poly(methyl methacrylate) to the fibre surface. Adhesion between the fibres and poly(methyl methacrylate) was evaluated by a tear-off method and by scanning electron microscopy. The results also suggest that laser irradiation enhances the wettability of the fibres by introducing active sites onto the fibre surfaces which react with the resin and impart stronger interfacial adhesion.