Dielectric properties of microcrystalline cellulose/multi-wall carbon nanotubes multi-scale reinforced EVA/VeoVa terpolymer

Abstract

Dielectric analyses were investigated on vinyl resin emulsion based on ethylene vinyl acetate/vinyl ester of versatic acid terpolymer (EVA/VeoVa) and its composites reinforced with microcrystalline cellulose and multi-wall carbon nanotubes. Dielectric spectra were measured in the frequency range from 10-1 Hz to 107 Hz and the temperature interval from -35°C to 130°C. Three dielectric relaxations were identified for the matrix. The first one, appearing at lower temperatures and higher frequencies, was associated with secondary β relaxation. The second one appearing above the glass transition temperature was attributed to the α relaxation due to the main glass transition of the terpolymer. The third dielectric relaxation appearing at higher temperatures and lower frequencies was attributed to α’ relaxation originating from the motion of more repeat units compared to the α one. The addition of the reinforcements into the matrix gave rise to three additional dielectric phenomena originating either from microcrystalline cellulose or matrix/reinforcement interfaces. Analyses of secondary dielectric relaxations at low temperatures by using the Havriliak-Negami model and those at high temperatures according to an adequate equivalent circuit model allowed probing reinforcement/matrix interactions. This dielectric study was complemented by the thermal, structural and morphological analyses based on differential scanning calorimeter (DSC), X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively

Preparation of PANI/CuPc/PDMS Composite Elastomer with High Dielectric Constant and Low Modulus Assisted by Electric Fields

“…Existing DEs usually have an inherent low dielectric constant (ε = 2–10), which makes it difficult to meet the high driving voltage (>100 kV·mm −1 ). In order to generate a larger drive at a relatively low driving voltage, the dielectric constant can be increased by adding a high dielectric filler, such as ceramic fillers (BaTiO 3 , SnO 2 , and Al 2 O 3 ) or conductive fillers (carbon fibers, carbon black, metal powder, polyaniline, and polypyrrole) and so on [ 12 , 13 , 14 , 15 , 16 , 17 ]. The composites filled with ceramic particles require higher filler content to achieve a high dielectric constant, and this results in decreased flexibility [ 18 ].…”