Synthesis of innovative multifunctional thermally-activated reactive species for elastomeric nanocomposite technology

The doctoral project was carried out in collaboration with Pirelli. The tire industry is always looking for new strategies to improve the performance of its products. The various elastomers used are not enough to obtain the desired characteristics. In order to increase its characteristics such as strength, adhesion, longevity, load, durability, it is necessary to add inorganic fillers such as silica and carbon black, but the interactions between rubber and filler are not always optimal. In this project, systems capable of both improving the dispersibility of fillers in the polymer matrix and systems capable of cross-linking elastomers have been investigated, in order to improve viscoelastic properties of the final material. The initial specifications required the synthesis of organic molecules stable at room temperature, but able to react thermally (above 100 ° C) with the polymer chain, forming strong and irreversible covalent bonds. Among the various classes of compounds were identified promising molecules capable to generate, at high temperatures, 1,3-dopolar nitrilimine-type species supplying cycloadducts with olefinic systems. We dealt with the synthesis of organic compounds, working on the nature of the substituents present in order to modulate their properties, the activation temperature and their reactivity. Each synthesized molecule was characterized by NMR, IR and thermogravimetric (TGA) analysis. Reactivity tests were also carried out on polymers to demonstrate their effective thermal anchoring. Subsequently, we focused on the synthesis of the functionalizers in sufficient quantity (in the order of grams) to conduct tests on tire compounds (polymer + filler + additives). These dynamic tests were carried out using RPA to highlight the possible positive effects of the functionalization of the polymers on the compound. Furthermore, tensile tests were carried out. The collected data, compared with those belonging to non-functionalized samples, served to highlight a variation in the viscoelastic properties (G ’, G’ ’, tanD). Finally, given the versatility of the species used, structural changes were made, so that they can be used for different applications; according to the directives requested by the company. The last part of the doctorate was dedicated to the scale up of some compounds identified as the most promising for industrial application. In addition, six months were spent abroad, at the University of Strasbourg, where new systems for polymer functionalization, based on non-covalent interactions (e.g. hydrogen bonds), were studied. The desired compounds were synthetized and characterized, and their properties were investigated, performing rheological measurements to measure the change of some properties such as viscosity.