Thermal evaluation of rubber compounds containing pecan nutshell powder for tire treads

This work presents the thermal study of rubber compositions with the addition of pecan nutshell powder, which is renewable and environmentally friendly, as a replacement for carbon black in treads for tires. Pecan nutshell is composed of cellulose, hemicellulose and lignin, and their quantity was evaluated by thermogravimetric analysis (TG) through the step-and-hold method. Thermal stability of the samples with pecan nutshell was verified by TG compared with the sample with only carbon black. The value of tan δ evaluated by dynamic mechanical analysis in the specific temperature values indicates the wet traction and rolling resistance for tires. Higher tan δ at 0 °C was observed in the samples containing pecan nutshell, which indicates better wet traction; however, the higher results observed at 60 °C indicate a worst rolling resistance. Results of oxidation induction time, by differential scanning calorimetry, show that the oxidation time increased with the addition of pecan nutshell in the compounds, indicating better antioxidant properties, justified by the presence of lignin.