Failure characterization of vibration welded polypropylene joints

VALERIA PETTARIN; LAURA FASCE; PATRICIA M. FRONTINI

Milwaukee, Wisconsin, USA

Conferencia; Annual Technical Conference of the Society of Plastics Engineers ANTEC 2008; 2008

The failure behavior of vibration welded polypropylene T-peel joints was investigated. The quality of welded joints was assessed using several mechanical tests including: smooth tensile, notched tensile, DENT and DART. The depreciation of properties was evaluated as the ratio between the properties of the pristine material and the joint. The morphological features of deformed and fractured materials were examined using polarized light optical microscopy and scanning electron microscopy. From our investigations it emerges that the vibration welding process resulted in low weld efficiencies for all mechanical testing techniques. SEM inspection of the fracture surfaces also revealed the presence of unwelded points and scarce material inter-diffusion consistent with the low weld efficiencies achieved. The investigations also revealed the drawing capability of the pristine material was negatively affected by the thermal history involved during the welding process. Contrary to pristine material behavior, welded samples developed a small outer plastic zone before fracture.