Laser Welding of Morphologically Dissimilar Thermoplastic Structures

This work explores a disruptive solution for joining morphologically dissimilar thermoplastic structures (MDTS). The industry uses thermoset adhesives to bond these materials. This approach presents some intrinsic drawbacks (e.g., low automation, lengthy, with low flexibility, prone to human error, may require heat to cure, releases harmful residues/fumes, and may preclude recyclability). This work investigates the potential of an adhesive-free concept based on laser transmission welding for joining morphologically dissimilar thermoplastic structures composed of non-cellular and cellular thermoplastics by controlling the heat input to the foamed thermoplastic and the heat transfer to the non-cellular counterpart. The joint quality was evaluated by performing lap shear testing and scanning electron microscopy to assess joint morphology, and then comparing the results with those of the adhesive-bonded version. Considering the exploratory nature of this work, promising results were achieved, with the best welded joints reaching approximately 74% of the strength of the traditional adhesive solution, establishing a basis for future research to optimize the process.