Evaluation of Stabilizing Additives Content in the Mechanical Properties of Elastomeric Compositions Subject to Environmental and Accelerated Aging

This research aimed to evaluate the ideal proportion of two stabilizers in elastomeric compositions indicated for tire sidewall. The stabilizers applied in different proportions were N-1,3-dimethyl-butyl-N'-phenyl-p-phenylenediamine (6PPD) and oligomerized 2,2,4-trimethyl-quinoline (TMQ). Nine compositions were prepared with 0.5, 1.5 and 2.5 phr of 6PPD combined with 0.5, 1.0 and 1.5 phr of TMQ. The compounds were exposed to accelerated aging processes, including thermo-oxidative, photochemical and ozone chamber. Also, the samples were aged in the environment for 440 days. At regular intervals, the samples were evaluated. Gas chromatography was used to quantify the content of 6PPD. Overall, the samples exposed to thermo-oxidative aging showed the greatest loss of mechanical properties (tear and tensile strength) as well as the 6PPD content. From the mechanical strength results, it was possible to conclude that the best combination of stabilizers was 2.5 phr of 6PPD and 1.0 of TMQ.