Effect of carbon nanotube location and dispersed phase on the dielectric properties of polypropylene/high-density polyethylene/carbon nanotube nanodielectrics

The effect of carbon nanotube location and dispersed phase on the dielectric properties of nanocomposites with carbon nanotubes (CNTs) and polypropylene/high-density polyethylene (PP/HDPE) blends was investigated. Different compatibilizers styrene-ethylene-buthylene-styrene copolymer (SEBS), ethylene-propylene-diene-methylene rubber (EPDM), and ethylene-propylene copolymer (EP) were used. In order to obtain a smaller HDPE phase, 0.1%(w/w) of CNT was added to a PP/HDPE (90/10) blend with 3%(w/w) of compatibilizer. Samples were processed in a twin-screw extruder with a controlled sequential mixing based on thermodynamic (using the wetting parameter, omega AB$$ {\omega}_{AB} $$) and kinetic parameters (such as melting temperature and melting flow indices). FESEM images show the formation of nanoblends for all compositions, with a dispersed morphology with HDPE droplets with a diameter of about 100 nm (measured with ImageJ (c) software) inside the PP matrix, and TEM images show the CNTs present in both phases. However, compatibilizers seemed to expel the nanoparticles from the dispersed phase, which may have contributed to a reduction of the dielectric constant of the CNT nanocomposites. Dielectric properties were evaluated through Impedance Spectroscopy, showing that CNTs contribute to the interfacial polarization and constant dielectric rise from 3.15@1 Hz (without CNTs) to 16.91@1 Hz (with CNTs, but no compatibilizer).

Automated summary

The effect of carbon nanotube location and dispersed phase on the dielectric properties of nanocomposites with carbon nanotubes and polypropylene/high-density polyethylene blends was investigated. It was found that the presence of compatibilizers expelled the nanoparticles from the dispersed phase, leading to a reduction in the dielectric constant of the CNT nanocomposites.