Effect of Surface Treatment on Adhesive Properties of Polycarbonate and Polyurethane Sealant

Polycarbonate (PC) was surface treated by atmospheric air plasma treatment technology, sandpaper grinding and coating primer. The contact angle, functional groups, micromorphology and chemical elements of PC surface were characterized. With polyurethane sealant as adhesive, and combining with peel tests and tensile shear tests, the influence of different surface treatments on the surface bonding properties of PC was studied. The results show that comparing with those without surface treatment, after plasma treatment the contact angle between PC surface and water or ethylene glycol decreased, the content of polar oxygen functional groups on the surface increased and the surface wettability was improved. The surface failure mode after plasma treatment and sandpaper grinding treatment was the same as that without surface treatment, which was the interface adhesion failure. The tensile shear strength after plasma treatment and sandpaper grinding treatment was slightly improved, but the bonding property was not significantly improved. After primer coating treatment, the surface changed to the smooth surface of water wave, the water contact angle decreased slightly comparing with those without surface treatment, the surface polar oxygen-containing functional group content increased, the surface failure mode changed to adhesive cohesion failure, the tensile shear strength increased by about 13 times, and the bonding property was significantly improved.