Potencial do óxido de grafeno na otimização de composto para banda de rodagem

Abstract

The advancement of the automotive industry has consolidated tires as indispensable components. Traditionally, carbon black (CB) is employed in high proportions to achieve the desired performance in tread compounds, which, however, contributes to fatigue processes and premature aging. The combination of CB with graphene-based nanoparticles, such as graphene oxide (GO), has been explored due to their superior mechanical and thermal properties. This work proposes a novel and more industrially viable method for incorporating GO, employing processing oil as a dispersing medium through mechanical mixing. Four GO concentrations (0.5, 0.75, 1.0, and 1.25 phr) were investigated in formulations designated T1, T2, T3, and T4, respectively. The compounds were prepared on a two-roll mill and consisted of natural rubber, CB N220, naphthenic oil, zinc oxide, stearic acid, sulfur, and N-cyclohexyl-2-benzothiazolesulfenamide. The materials were characterized by rheometry, Mooney viscosity, hardness, rubber processing analyzer, tensile, abrasion and tear strength, dynamic mechanical analysis, linear thermal conductivity, field emission scanning electron microscopy, and dispersion testing. The results showed that the addition of GO did not significantly alter the rheological properties, curing times, or mechanical properties. However, formulation T2 (0.75 phr) exhibited an increase in storage modulus at low strains (G'0) and Payne effect (ΔG'), suggesting that mixing on a two-roll mill was not effective in enhancing filler-matrix interactions. On the other hand, the same formulation showed a 10.6% increase in linear thermal conductivity compared to the control, attributed to the formation of a filler network. This result was confirmed by FE-SEM micrographs of the cryogenic fracture surface of this composition. Dynamic mechanical analysis also revealed increased stiffness, with increments in storage modulus (G') of 1.7, 5.2, and 1.3% for T1, T2, and T3, respectively, at 25 °C. Similar behavior was observed for the loss modulus (G''), with increases of 6.1, 7.6, and 7.3%. Although T4 exhibited a reduction in G' and G'', this formulation simultaneously showed a 4% increase in tan δ at 0 °C, along with reductions of 16.2% at 60 °C and 13.5% at 100 °C, associated with improved wet grip, reduced rolling resistance, and lower heat buildup. These results highlight the potential of hybrid reinforcement as a viable alternative to enhance performance and extend the service life of tread compounds. [resumo fornecido pelo autor]