Structure and Dielectric Properties of Polypropylene/Zinc Iron Oxide Nanocomposites

This study explores the effects of zinc iron oxide <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\left(\text{ZnFe}_{2} \mathrm{O}_{4}\right)$</tex> nanofillers on the structure, thermal properties, and dielectric performance of polypropylene (PP) nanocomposites. Nanofillers were added at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.5,1,2$</tex>, and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$5 \text{wt}. \%$</tex> to evaluate their effects. Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) analyzed the material's morphology and thermal behavior, while dielectric breakdown strength was tested under AC and DC conditions according to ASTM D149 and ASTM D3755 standards, respectively. Results showed that <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{ZnFe}_{2} \mathrm{O}_{4}$</tex> increased the crystallization temperature with more filler. SEM images revealed an even distribution of nanoparticles at lower levels but agglomeration at higher concentrations. Dielectric breakdown strength decreased with increasing filler, with pure PP showing the highest values of 158 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm 8 \text{kV} / \text{mm}$</tex> (AC) and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$327 \pm 10 \text{kV} / \text{mm}$</tex> (DC), while, at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$5 \text{wt}. \%$</tex> filler, breakdown strength fell due to weak spots from agglomeration.