Study of the laser-material interaction for innovative hybrid structures: Thermo-mechanical characterization of polyethylene-based polymers

This study deals with the experimental analysis of the effects of laser radiation on semi-crystalline polyethylene-based polymers. This paper has been developed as basis for future development of an innovative joining system, based on laser technology, to produce hybrid structures consisting of metal and polymer parts. Several process monitoring techniques, such as mechanical tensile test, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), flat-top cylinder indentation test (FIMEC) and infrared analysis (FTIR) have been used to evaluate the thermo-mechanical properties of the tested materials, with the aim to identify the technological process window for the joining process. The investigation, focused on two thermoplastic samples in high density polyethylene (HDPE) and polyethylene terephthalate (PET), aimed to investigate any structural changes caused by the laser irradiation of the polymer materials. Results showed no degradation for PET material and only a minor oxidation effect for black high-density polyethylene (HDPE) sample. The achievements of this study are of crucial importance for the identification and setting of the optimal irradiation parameters during laser joining operations, thus avoiding ineffective heating or excessive degradation of the material.