Electrical properties of low density polyethylene/ZnO nanocomposites: The effect of thermal treatments

Thermal and Dielectric Behaviour of Polymer-Based Nanocomposites Flexible Sheets as Highly Stable Dielectric Materials

The silica zinc oxide nanoparticles filled poly-vinylidene-fluoride (PVDF)-based nanocomposite flexible sheets (NC FSs) are synthesized by co-precipitation method. The X-ray diffraction patterns reveal the development of various diffraction planes related to zinc oxide (ZnO) and SiO2 phases. The crystallinity of ZnO phase is decreased with increasing weight percent (wt.%) of silica nanofillers (NFs). The scanning electron microscope microstructure of synthesized PVDF-based NCs FSs is changed with increasing wt.% of silica NFs. The energy-dispersive X-ray spectroscopy and Fourier-transform infrared spectroscopy analyses confirm the presence of different elements and the formation of chemical bonding between them. In high temperature region, the weight-loss of synthesized PVDF-based NCs FSs is decreased from 89.90% to 49.26% with increasing wt.% of silica NFs. The values of dielectric permittivity, loss-factor, impedance, and AC-conductivity of PVDF-based NC FSs synthesized for maximum amount of silica NFs are found to be 13.7, 0.03, 0.16 MΩ, and $19.9\times {10}^{-6}$  S/m, respectively. Results show that the synthesized PVDF-based NC FSs are the potential candidates of light emitting diodes and energy storage devices.

Effect of aluminum nitride concentration on different physical properties of low density polyethylene based nanocomposites

In this study, blends of low-density polyethylene (LDPE)/aluminum nitride (AlN) ceramic nanocomposites have been prepared through melt blending technique. Increased loading of AIN leads to reduction in tensile properties but improvement in rheological property (storage modulus). The rheological behavior tends to become unique at higher frequencies (≥10 rad/s). Differential scanning calorimetry (DSC) results show that the total crystallinity has decreased with the increase in AlN loading in the composites. It is seen that there is an improvement in electrical conductivity, dielectric constant, and flammability properties with the addition of AlN in the nanocomposites. The experimental data of tensile modulus, electrical conductivity, and dielectric constant have been fitted with some available theoretical models to check the models’ applicability for the present composite systems. Results show that only Nicolais-Nicodemo model, McCullough model, and Rahaman-Khastgir model are applicable for predicting the tensile modulus, electrical conductivity, and dielectric constant of the composites, respectively.

Highly Efficient Interfaces in Nanocomposites Based on Polyethylene and ZnO Nano/Hierarchical Particles: A Novel Approach toward Ultralow Electrical Conductivity Insulations

Polyethylene nanocomposites based on functionalized ZnO nano/hierarchical particles with highly effective interfacial surface area are presented, for the next generation of ultralow transmission-loss high-voltage DC insulating materials.

Carbon Nanotube Conductive Networks through the Double Percolation Concept in Polymer Systems

We investigated the electrical conductivity and percolation behavior of binary and ternary nanocomposites based on multiwalled carbon nanotubes (MWCNs) using polypropylene (PP) and a blend of PP with cyclic butylene terephthalate (CBT). The nanocomposites were prepared by diluting a commercial 20 %wtMWCNT PP masterbatch using optimized melt-mixing conditions. The concentration of carbon nanotubes in the diluted PP samples was as low as 0.5 % and as high as 15 % in weight. For the PP/CBT blend CBT concentration was varied up to 40 %wt while the loading of CNT was from 0 to 5 %wt. SEM and TEM techniques were used to examine the quality of the dispersion and the formation of nanotube networks within the polymer matrix. TEM and Raman spectroscopy results showed that for the diluted PP/MWCNT composites the nanotubes are well aligned in samples obtained the microinjection molding process, although the level of alignment is less with crystalline PP than in an amorphous matrix such as polycarbonate (PC). FTIR and XRD results revealed that the orientation of both polymer chains and crystals decreased with the incorporation of nanotubes into PP. The electrical conductivity was also significantly altered by the nanotube alignment in a PP matrix, as was previously observed for PC/MWCNT composites; the conductivity decreased and the percolation threshold rose in highly sheared samples; however, the presence of a crystalline phase improved the conductivity even for high shear conditions through the phenomenon of double percolation threshold. This last concept refers to the requirement that the filler-rich phase be continuous and conductive and not to the existence of two percolation thresholds at two different CNT concentrations. The electrical conductivity of PP/CBT blends was also improved through a double percolation that is the basic requirement for the conductivity of the ternary nanocomposites.