Charge transport in low density polyethylene based micro/nano-composite with improved thermal conductivity

In this work, effect of nano-sized SiO2 and micro-sized hexagon boron nitride (h-BN) on charge transport behavior of low-density polyethylene (LDPE) has been investigated. LDPE based micro-nanocomposites samples were prepared through hot-press method by adding 20 nm-SiO2 and 5 mu m-h-BN as the fillers. Isothermal surface potential decay measurement was carried out with sample temperature of 40 degrees C and relative humidity of 23%-29% to obtain trap depth, carrier mobility and field dependent conductivity, by which the effect of fillers on charge transport manners could be estimated. In addition, thermal conductivity test, scanning electron microscopy and differential scanning calorimetry had been employed to assist the analysis of the filler effect. Test results indicated that the crystal structure of LDPE was changed by the doping of the fillers. With the increase of the micro-and nano-filler content, the trap depth tended to be deeper firstly then became shallower. Both band and hopping transport of charge occurred in the composite, and the carrier mobility was dependent upon the filler content. It is suggested that the addition of the nano-sized SiO2 and the microsized h-BN particles has an effect to inhibit the charge transport, where a synergistic effect among the nano-sized and the micro-sized particles is expected to modify charge trapping and de-trapping behavior.