STRUCTURE AND DIELECTRIC PROPERTIES OF POLYPROPYLENE CONTAINING ZINC IRON OXIDE NANOFILLER

Cross-linked polyethylene (XLPE) is commonly used in high-voltage cable insulation due to its favorable dielectric properties. However, its thermoset nature limits recyclability and thermal performance. Polypropylene (PP), a recyclable thermoplastic, offers better thermal stability, making it a potential alternative. Despite this, PP's dielectric performance under high-voltage conditions can be insufficient, especially when filled with single metal oxide nanofillers that absorb moisture. Zinc iron oxide (ZnFe₂O₄), a multi-metal oxide with low moisture absorption and thermal stability, may offer a solution, yet its application in PP nanocomposites remains underexplored. This study investigates the structural, thermal, and dielectric characteristics of PP/ZnFe₂O₄ nanocomposites with 0.5, 1, 2, and 5 wt.% filler content. SEM and DSC analyses revealed improved crystallization behavior with ZnFe₂O₄ acting as a nucleating agent. Good nanoparticle dispersion was observed at lower filler loadings, while higher content led to agglomeration. AC and DC breakdown strength tests (ASTM D149, D3755) showed pure PP had the highest strength (158 ± 8 kV/mm AC; 327 ± 10 kV/mm DC). The 0.5 wt.% sample exhibited comparable values, while 5 wt.% resulted in the lowest performance (144 ± 10 kV/mm AC; 203 ± 23 kV/mm DC). These findings confirm that low ZnFe₂O₄ content enhances PP's thermal and dielectric properties for potential HV insulation applications.