Interfacial polarization effects on dielectric properties in flax reinforced polypropylene/strontium titanate composites

Abstract

Interfacial polarization or Maxwell-Wagner-Sillars effect using a dielectric study with the addition of strontium titanate and flax fiber reinforcement on a polypropylene matrix were investigated. Scanning electron microscopy (SEM) was performed for characterizing the fabricated sample to identify its fibers, ceramic, and polymer matrix regions. In the presence of strontium titanate and flax fiber reinforcement, the SEM images show signs of small ceramic agglomerates with fewer voids on fiber surfaces and a homogeneous distribution of fillers in the polymer matrix. The dielectric measurements revealed that dielectric relaxation occurs at low temperatures. The interfacial polarization was modeled using the Havriliak-Negami function, whereas the theoretical calculation shows a good best fit line with the experimental ones. The interfacial relaxation strength showed an increase of 202.54% from neat polypropylene matrix to flax reinforced polypropylene-strontium titanate composite from 0.866 to 2.62, respectively. This increase in dielectric strength is attributed to the accumulation of charge carriers at polypropylene-flax, polypropylene-strontium titanate, and strontium titanate-flax fiber interfaces. The potential use of these materials is in layered printed circuit board applications.