Interazione del fascio laser in pelle sintetica di nanocomposito polimero-grafene per ottenere tracce conduttive prive di metallo

This thesis work was carried out in collaboration between University of Turin and the Department of Electrical, Electronic and Multifunctional Materials of CRF, the FCA Research Centre. It proposes an interesting and innovative research based on a hypothetical modelling of interaction between the laser beam and the graphene-polymer matrix nanocomposite with the purpose of obtaining electrically conductive tracks for printed circuits boards embedded in polymers-based components. Then, a practical realization of laser tracks printed on the samples, has made it possible to verify, analyse and better understand those hypothetical mechanisms that were only previously hypothesized. This work is based on the laser technique which promotes an action of ablation on the polymer surface that leads to formation of conductive track by removing of polymer matrix and it is characterized by low cost, high versatility and great precision: the optimal methodology for creating printed circuits boards. This innovative treatment has been performed on a new technological synthetic leather which cover the dashboard of the vehicle and aesthetical parts for automotive interiors and it is characterized by an added layer of thermoset polyurethane matrix mixed with graphene sheets nanostructures. This thin nanocomposite layer could act a crucial role: initially non-conductive, it would be able to carry the current when it is functionalized by laser irradiation. The matrix of thermoset polyurethane (PU) is characterized by lightness but enough resistant while the graphene sheets nanostructure, gives an important increment of strength and conductive property, obtaining a mono-material that have a greater facility of recycling, without thinking about the separation and the disposal of different components. The practical realization of laser tracks printed on the samples, has made it possible to verify, analyse and better understand those mechanisms that were only previously hypothesized. The processing parameter of laser that has been modulated are three: the power (P), expressed in percentage [%] that could vary from 5% to 100%; the scan speed (v), in mm/s and the number of repetitions (N). The fundamental aspect studied is the possibility to combine the parameters P, v and N to each other, in order to find the most efficient laser conditions. In fact, it could be obtained the same results either by increasing the power and decreasing the scan speed or by reducing the power and increasing the number of repetitions (and vice versa). Finally, other factors could influence the laser processing, such as the type of the gas flux used during the laser treatment, used to avoid the oxidation of the treated surface. In conclusion what it results from the analysis and tests performed, it has turned out to be in line with the reasoning and hypothesis made. Thus, thanks to the practical realization of the trace by laser irradiations, it has been possible to better understand the mechanisms of the laser-matter interactions and to relate it with the theoretical models only previously hypothesized. This work is only a small beginning of what can be an interesting research, that certainly has still much to reveal.