Influência da combinação sílica/negro de fumo e das etapas de processamento no desempenho de bandas de rodagem de pneu de carga

Abstract

One of the major challenges in the rubber industry today is related to the relationship between durability, safety and economy for tire applications. Important progress on rolling resistence reduction with good wet grip was achieved replacing carbon black by silica-silane coupling agent system. The aim of this work was to develop an elastomeric compound for a truck tire tread combining the reduction of the rolling resistance and the improvement in the wet grip. Eight compounds were prepared: two formulations based on carbon black (varying the processing conditions), five formulations with the partial replacement of the carbon black by a silica-silane coupling agent system (varying the processing conditions and the silane content), and one formulation with the total replacement of the carbon black by silica. Rheometric, physical, chemical, mechanical, and dynamic-mechanical properties were evaluated. The results were compared to a standard formulation based on a typical formulation of truck tire treads. From dynamic mechanical analysis, the results showed that for the compound with 15 phr of silica, 3 phr of silane, and three processing steps, the rolling resistance decreased by 10% compared to the standard compound, and the wet grip increased by 18.5%. The partial use of silica reduced the abrasion loss, confirming the durability of the compound. The formulation with only carbon black and prepared in three processing steps also had good results, showing that more processing steps lead to a better dispersion of carbon black. The compounds with 1.5 phr of silane showed unsatisfactory results; the filler does not interact sufficiently with the polymer, probably because the low content of coupling agent. The results showed that the use of silica and the processing conditions, as well as the quantity of silane, were important to improve filler-polymer interaction and to promote a general improvement in the properties.