Desenvolvimento de bandas de rodagem com menor resistência ao rolamento e menor impacto ambiental

Abstract

The tire industry is in constant development in order to make its products safer, more durable, ecologic and energy saving. To achieve these objectives, improvements in the properties of abrasion resistance, wet grip and rolling resistance are necessary, beside the use of eco-friendly raw materials.The aim of this study was to develop an elastomeric formulation of tire treads for passenger car in order to improve these technical characteristics and to reduce the environmental impacts through the use of alternative additives. Therefore, the naphthenic oil was replaced by a vegetable oil, and zinc oxide (ZnO) by an additive with a lower percentage of zinc. Moreover, full/part carbon black replacement by rice husk ash was performed. The characterization of these ingredients was carried out by analyzing the specific surface area, the distribution of the particle size and pores and the pH analysis. A standard formulation for passenger car tire treads was developed (6 phr of naphthenic oil and 40 phr carbon black). From this formulation, new formulations were developed with total replacement of carbon black (NF) (40 phr) by ash rice husk (CCA) (20, 40, 60, 80 and 100 phr) and partial replacement of NF (30NF/10CCA and 20NF/20CCA). In these formulations, vegetable oil (3 phr) was used instead of naphthenic oil (6 phr). The CCA was evaluated in comparison with silica and treated rice husk ash (CCAT). Moreover, the silanization process was evaluated in one, two and three step processes. In the last stage of this study, the formulation with the best properties was chosen for studying the replacement of ZnO by organic zinc. The results showed that increasing the number of silanization steps caused a reduction of the Payne effect values related to a better polymer-filler interaction. However, no significant improvements were found in the mechanical properties by increasing the number of stages. The results showed that it is possible to completely replace the naphthenic oil by vegetable oil, zinc oxide for organic zinc and to partially replace the CCA by NF gaining 21% in abrasion resistance and 18.8% in rolling resistance properties. These results are of great importance for the tire industry, combining sustainability to the use of raw materials from renewable sources and reuse of an agro-industrial waste.