The Antioxidant Effect of Lanthanum Complex in Natural Rubber

Abstract

Mixed antioxidants composed of antioxidant N-phenyl-N'-isopropyl-p-phenylenediamine (IPPD) and lanthanum (La) complex were added as a filler to prepare natural rubber (NR) composites. By mechanical testing, X-ray photoelectron spectroscopy, and thermogravimetric analysis, a string of data, including the mechanical properties, the variation of chemical surface characterization, and the thermo-oxidative decomposition kinetics parameters, was presented in this article to study the antioxidant effect of the mixed antioxidants in NR. The density function theoretical calculations were also used as an assistant to study the thermo-oxidative aging mechanism of NR and the different function mechanisms of antioxidants IPPD and La complex. The data revealed that except for functioning as a labile-hydrogen doner which was similar to antioxidant IPPD, this La complex had strong coordination abilities and large coordination numbers, resulting in the high efficiency in enhancing the thermal-oxidative stability of NR.