Mechanisms of AC Breakdown Strength Evolution in Polypropylene/Elastomer Blends during Thermal Cycling aging

In response to the "Dual Carbon"initative, recyclable polypropylene (PP) has become a promising alternative to cross-linked polyethylene (XLPE) for cable insulation. To overcome the inherent brittleness of iPP, PP/elastomer Blends are used, yet their long-term stability under temperature variations remains unclear. Thus, this study investigates the evoluation of AC breakdown strength in PP/elastomer blends during thermal cycling aging. Multiscale Structures were characterized via XRD and SEM. The results showed a non-monotonic variation in breakdown strength, governed by the competition between recrystallization and structural damage accumulation. Initially, crystal structure was enhanced by recrystallization during heating process, leading to a slight improvement on AC breakown strength. Subsequently, crystal structure was destroyed while the elastomer phase coarsening happened, ultimately causing a sharp decline in breakdown strength. This work provides key insights for the reliability assessment of recyclable cable materials.