A Multi‐Scale Assessment of the Aging Mechanisms of PP / SEBS Composites

ABSTRACT Polypropylene (PP) composites possess excellent electrical insulation and have become a new trend in the development of power cable insulation. The stability of the molecular chain directly determines the service life of power equipment. Therefore, it is essential to investigate the thermal aging behavior of the styrene ethylene butylene styrene (SEBS) modified PP cable insulation. In this paper, the independent aging mechanisms of each component in systems are studied using a multi‐scale evaluation method. The experimental results show that with the progression of aging, the mechanical and electrical properties of the composite decrease significantly. The simulation results indicate that the activation energies for hydrogen dissociation of SEBS are 339.08 and 362.19 kJ/mol, respectively, both lower than that of pure PP (374.65 kJ/mol). Furthermore, oxygen is more likely to penetrate and participate in the thermal oxidative aging reaction of the molecular chains in the PP/SEBS composites. This induces molecular chain scission and the generation of oxygen‐containing functional groups, which in turn alters the material structure and results in the degradation of macroscopic electrical properties. This work provides significant guidance for the research on thermal aging control of PP/SEBS composites.