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Effect of field variation (a) and Temperature (b) on charging currents of LDPE and LDPE/2.5C at 30˚C30˚C.
Source publication
This paper discusses the charge transport and accumulation in clay-containing LDPE (low density polyethylene) nanocomposites. LDPE is shown to host charges of both polarities in the form of homo and heterocharge when subjected to high electric fields. The addition of nanoclays has been shown to always increase the high field DC conductivity of the...
Contexts in source publication
Context 1
... low field dielectric response of these materials has been thoroughly investigated and the findings are reported elsewhere [13]. Up to 5 wt% of clay, the low-field conductivity was found to be negligible and accordingly it is clear that the addition of clay leads to a much stronger field dependency in the conductivity, as illustrated in Figure 3a. ...
Context 2
... α and β are the temperature and electric field coefficients respectively. The dependency to electric field is shown in Figure 3a where the DC conductivities for neat LDPE and LDPE/2.5C nanocomposite are illustrated at 30˚C and under different fields: 30, 40 and 50 kV/mm. ...
Citations
... The space charge profile has been determined using Pulsed Electroacoustic technique (PEA) where the acoustic waves created as a result of the interaction of a pulsive electric field and space charge inside the material is detected by a transducer. More information can be found in [13]. ...
This paper investigates the effects of organomodified montmorillonite (clay) and styrene-(ethylene-co-butylene)-styrene triblock copolymer (SEBS) on the morphological and electrical properties of polypropylene (PP). A series of binary PP-clay nanocomposites along with nanocomposites having a blend matrix were prepared. The nanofillers were found to be well-embedded into the polymeric matrix with a high degree of dispersion. The microstructure of the blend matrix revealed a co-continuous structure for the equal proportion of the two polymers. This was shown to control the localization of nanofiller by triggering them to migrate into the SEBS phase, mostly accommodating in the interface and creating a strong network which eventually resulted in more exfoliation of clay platelets and comparable/superior electrical properties comparing to binary nanocomposites. The incorporation of clay resulted in a solid-like rheological behavior which was more enhanced in blend nanocomposites due to the stronger network of nanofiller. The dielectric spectra of the nanocomposites revealed two major relaxation processes aroused by the presence of clay. A new relaxation process was observed for the nanocomposites with the blend matrix, related to the SEBS phase. Both blending and nanofiller inclusion resulted in less accumulated space charge. A significant improvement in the AC breakdown strength of PP was witnessed upon addition of clay. Despite the less inherent breakdown strength of SEBS, the blend nanocomposites showed even more enhanced breakdown properties confirming the further improvement of nanofiller network structure.
... Fuse et al found that the conductivity of polyamide-6 became reduced with the loading of nanofiller (NaMg 2.5 Si 4 O 10 F 2 ) [16]. However, Eesaee et al measured the charging current of LDPE and its nanocomposite and calculated the DC conductivity, they found that the DC conductivity increased with the increase of nanoclay in LDPE [17]. In addition, invest igations have been also performed with respect to charge transport behaviors of poly mer based micro/nanocomposite. ...
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 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 SiO2 and the micro-sized 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.
To investigate space charge behavior in double-layered cable insulation, a one-dimensional axisymmetric model for bipolar charge transport is built in this work. Effects of temperature gradient and electric field gradient in the radial direction are considered. The transient distribution of space charge and electric field under polarity reversal voltage is simulated with the developed model, and then the influence of interface position is analyzed to guide the design of double-layered insulation. The results indicate that space charge and electric field distributions are affected by temperature gradient and voltage polarity. Under polarity reversal voltage, the electric field is intensified by the residual space charge generated before polarity reversal, which causes the severe electric field distortion. In addition, the comprehensive electric field distortion factor is the least when the interface is located at the middle of the insulation layer, which is more beneficial to the stable operation of cable.
