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

Abstract

In this work, effect of nano-sized SiO 2 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-SiO 2 and 5 µm-h-BN as the fillers. Isothermal surface potential decay measurement was carried out with sample temperature of 40 °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 SiO 2 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.

Influence of thermally induced self‐assembly shish‐kebab crystal on charge transport behaviour in polypropylene/elastomer blends

“…Hopping conduction model is a possible mechanism for the charge transport of PP. In this model, it is assumed that the measured surface potential decay is mainly determined by charge transport through the sample bulk, hence the bulk conductivity σ of the sample could be estimated by [30], …”

“…The relationship between the σ and the electric field E f for a hopping conduction can be expressed by [30],…”

Charge transport behavior in gamma‐ray irradiated poly(ethylene terephthalate) estimated by surface potential decay

“…Figure 4b shows the trap centres for electron at 0.912 and 0.808 eV. It is considered that the trap centres would have remarkable influence on charge transport behaviour of the sample due to their higher densities, thus are selected for discussion in the following parts [21]. Figure 5 depicts the effect of gamma-ray irradiation dose on the trap centre of PET.…”

Solubility and Diffusivity of Polar and Non-Polar Molecules in Polyethylene-Aluminum Oxide Nanocomposites for HVDC Applications

“…Good reviews on nanocomposites for electrical applications include [6,[25][26][27][28][29][30][31]. One hypothesis for the conductivity reduction in nanocomposites is that electrons and holes are trapped in deep traps in the nanoparticle surface [10][11][12][13]. A complementary hypothesis is that ions and molecules with permanent dipole moments, such as water and crosslinking by-products, are also attracted and adsorbed onto the nanoparticles, resulting in the cleaning of the polyethylene matrix [9,14].…”

“…A low electrical conductivity is a necessary condition for a good HVDC insulator material, but several other electrical and mechanical properties are also of importance. Fortunately, PE/Al 2 O 3 nanocomposites typically have improved properties when compared to pure PE, including a reduced space charge accumulation [15][16][17][18] dielectric permittivity [19,20] and thermal conductivity [12]. Additionally, an increased elastic modulus [21,22], tensile strength [23] thermal stability [22] and dielectric breakdown strength [15][16][17]24] has been reported.…”