Evaluation of vulcanization systems in natural rubber elastomeric tire sidewall compositions with lignin as a stabilizing agent

This work aimed to evaluate the influence of different acceleration systems on the properties of elastomeric compositions employed on the tire sidewall by means of the use of a lignin extracted from Eucalyptus as a substitute for oligomerized 2,2,4-trimethyl-quinoline (TMQ), a chemical additive of the rubber industry. For this purpose, six formulations were prepared varying the stabilizer type, TMQ or lignin for each acceleration system. The characterization was performed through rheological and mechanical properties, before and after accelerated aging in an oven and ozone chamber. In general, compositions with TMQ or lignin did not show significant differences in the results; however, different behaviors were observed in the three acceleration systems studied. The crosslink density decreased as the conventional acceleration system changed to semi-efficient and efficient. After accelerated aging, the specimens prepared with the semi-efficient and efficient systems showed the best retention results of the tear and tensile strength properties. In the ozone environment, samples prepared with the conventional and efficient system showed cracks on the surface. Therefore, it can be concluded that the semi-efficient system presented the best performance and that lignin can be used as a stabilizing additive, as it does not prejudice the natural rubber elastomeric compounds properties.