The effects of excimer laser irradiation on the surface morphology and self-adhesion properties of some engineering polymers as evaluated by ultrasonic welding

Excimer laser irradiation provides a new method for polymer surface treatment. The ablation rates and the resulting microstructures of various engineering polymers such as acrylonitrile butadiene styrene (ABS), polystyrene (PS), polycarbonate (PC), nylon 6 (PA6), poly(ethylene terephthalate) (PET) and polyimide (PI), were investigated subsequent to irradiation by Krf excimer laser. SEM (scanning electron microscopy) reveals that after laser treatment the polymer morphology is not only related to the laser parameters, but also to the polymer optical properties and to the evolution of structures which are produced during irradiation. The effects of excimer laser parameters on the depth of ablation and weight loss for different polymers were investigated. The effects of laser irradiation on the thermal properties (T-g or T-m) of the different model polymers were investigated using DSC. It was found that the T-g and T-m of these materials decreased as a result of laser treatment. indicating the degradation effect of laser irradiation. Laser treatment improved the ultrasonic weld strength of PS and ABS samples compared to the untreated samples. In comparison to the untreated samples, the ultrasonic weld strength of PS samples could be increased by as much as 816% and the corresponding break strain could be increased by 59%, using optimal irradiation conditions (1000 pulses using 180 mJ at 20 Hz). Similarly, the ultrasonic weld strength of ABS samples could be increased by as much as 464%, and the corresponding break strain could be increased by 70% using optimal irradiation conditions (1000 pulses using 180 mJ at 20 Hz).