Polyethylene-based composites containing octaisobutyl polyhedral oligomeric silsesquioxanes obtained by extrusion

Melt blending with a twin-screw extruder was tested as a method for producing polyethylene (PE)-based nanodielectrics containing octaisobutyl polyhedral oligomeric silsesquioxanes (OibPOSS). An extrusion temperature profile with comparatively low barrel zone temperatures (110 °C-130 °C) was employed and two rotation speeds (50 and 200 rpm) were investigated in order to achieve PE/OibPOSS nanodielectrics bearing homogeneous OibPOSS dispersion and improved dielectric properties. The resulting composites were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, laser scanning confocal microscope, progressive-stress breakdown tests and broadband dielectric spectroscopy. The results showed that the rotation speed employed in the extrusion process had some effects on the dispersion of OibPOSS. However, it had little influence on the properties of the resulting composites. For composites extruded at both 50 rpm and 200 rpm, the ones containing 1 wt% OibPOSS presented dielectric properties similar to those of LDPE, whereas the ones containing 5 wt% OibPOSS presented dielectric properties inferior to those of LDPE.