Diode laser welding of polypropylene:: investigations of the microstructures in the welded seam

Laser welding of thermoplastic polymers is a non-contact process especially efficient for joining thermoplastic polymers. This innovative technology is already used for industrial series production in different sectors (automobile, packaging....). The majority of the basic research concerns the weld strength depending on polymer nature, optical properties, butt design and process parameters. Nevertheless, a lack of knowledge concerning the influence of thermal history of the weld seam on morphology of semicrystalline polymer still exists, when this parameter strongly influences the strength of the weld. Actual results of diode laser transmission welding (LTW) experiments on polypropylene, a semicrystalline polymer widely used in industry, could contribute to a better understanding of the process itself and to success in practical applications.