Fabrication and dielectric properties of highly loaded polypropylene micro- and nano-composites

Nanoparticles and microparticles of hexagonal boron nitride (hBN) were added to polypropylene (PP) powder to produce 50 wt% nano and microcomposites by planetary milling. A nanostructured microcomposite containing 25 wt% of microparticles and 25 wt% of nanoparticles was also prepared to ally the improved properties of micro and nanocomposites. Thermo Gravimetric Analyses were conducted to ensure that there was no contamination during fabrication. Results show that the breakdown strength is increased by about 20% with addition of nano hBN when compared to that of neat PP. On the contrary, the microcomposite sample shows a poor dispersion and lower breakdown strength, observations being likely associated to an inhomogeneous sample. Dielectric Spectroscopy shows that the hydrophily of boron nitride leads to an increases water uptake in the samples, and so, an increase of the conductivity phenomenon.