Vibration welding of polypropylene-based nanocomposites - The crucial stage for the weld quality

Thermoplastic nanocomposites used for vibration welding are compounded on a twin-screw extruder by dilution of a concentrate masterbatch containing 14 vol% of filler. They are butt welded under different weld pressures by a linear vibration welding machine. By means of a quick ramp-down technology, this machine enables a very short vibration damping time of about 40 ms. The influence of different damping time on the weld strength of various materials is investigated. The experimental results are compared also with the results of simulation. In the case of nano-silica filled polypropylene, no impact of the damping time on the weld quality is detected and the possible reasons for this observation are explained.