Dielectric properties of polymer nanoparticle composites (original) (raw)
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Assemblies of Titanium Dioxide-Polystyrene Hybrid Nanoparticles for Dielectric Applications
Chemistry of Materials, 2010
Macroscopic assemblies of hybrid nanoparticles composed of titanium dioxide core surrounded by covalently grafted polystyrene corona have been prepared by a combination of phosphonate coupling and "click" chemistry. The attached polymer chains existed in the brush regime, with grafting density inversely proportional to the degree of polymerization. Solution casting afforded preparation of robust films of the composite material where all the polymer chains were covalently bound to the uniformly distributed inorganic particles. Inorganic content from 60 to 80 wt % (27 to 50 vol %) was obtained by varying the molecular weight of polystyrene as well as by using the mixture of high and low molecular weight polymer for grafting. The TiO 2 grafted with 10 5 g/mol polystyrene had a volume fraction of nanoparticles of 27% and exhibited glass transition at 110°C and ∼100% extensibility above T g. Thin films of this material had a dielectric constant of 6.4 and a dielectric loss of 0.04 at 1 kHz.
Synthesis and dielectric studies of poly (vinyl pyrrolidone) / titanium dioxide nanocomposites
IOP Conference Series: Materials Science and Engineering, 2015
In this paper, we present the synthesis of poly vinyl pyrrolidone (PVP) / titanium dioxide nanocomposites via sol-gel technique. The structural and dielectric properties of the samples were also analysed in this work. PVP doped with varying concentrations of TiO 2 are prepared by the sol-gel route. The prepared composites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and impedance spectroscopy. XRD and TEM confirm the presence of TiO 2 nanoparticles in the composites. The dielectric response and the AC electrical conductivity of the samples are investigated for the frequency range 1 kHz-2MHz at room temperature. The dielectric studies show low values for dielectric constant and loss at high frequencies.
Dielectric response and energy storage efficiency of low content TiO2-polymer matrix nanocomposites
Composites Part A: Applied Science and Manufacturing, 2015
TiO 2 /epoxy nanocomposites were prepared at different filler concentrations varying from 3 to 12 phr (parts per hundred resin per weight). The dispersion of TiO 2 was examined by Scanning Electron Microscopy and proved to be adequate. Differential Scanning Calorimetry was implemented to determine the glass to rubber transition temperature of the polymer matrix. The dielectric analysis was performed via Broadband Dielectric Spectroscopy in a wide frequency and temperature range. Five different mechanisms were observed in the spectra of the examined composites which are identified, in terms of increasing temperature at constant frequency, as c, b, Intermediate Dipolar Effect (IDE), a and Interfacial Polarization (IP) relaxation modes. The activation energies of all relaxation modes were calculated. Finally, the dielectric response of the TiO 2 nanocomposites compared to that of the TiO 2 microcomposites reveals that the former exhibit significantly higher energy storage efficiency even at lower TiO 2 concentration than the corresponding of the microcomposites.
Advanced Composite Materials, 2019
Effects of particle size on the dielectric properties of polymer matrix flexible nanocomposites were studied. Synthesized barium titanate (BaTiO 3 ; BT) nanoparticles (NPs) with different sizes were effectively dispersed in the matrix polymer using a simple phase separation method. The dielectric responses of free-standing thin composite films were studied by impedance spectroscopy. The interactions between nanoparticles were also studied by finite element analysis and compared with experimental data using a time harmonic-electric current solver in the AC/DC module of COMSOL Multiphysics® 5.2. The dielectric permittivity of polymer matrix nanocomposites was remarkably affected by the BT particle size, while the dielectric loss did not show any noticeable changes. The real permittivity exhibited the highest value when the BT particle size was near 100 nm. The calculated energy density based on measured real permittivity and breakdown strength was as high as 17.24 J/cm 3. The dielectric properties of polymer matrix nanocomposites can be improved by controlling the particle size of nanofillers in conjunction with surface treatment of fillers.
Japanese Journal of Applied Physics, 2012
A poly(methyl methacrylate)-doped titanium dioxide (PMMA:TiO 2) nanocomposite film was obtained by spin coating the nanocomposite solution onto a silicon substrate. The nanocomposite solutions were prepared by dissolving the PMMA and TiO 2 nanopowder in three different types of organic solvent, namely, toluene, tetrahydrofuran (THF), and acetone. We found that the dielectric properties of the PMMA:TiO 2 nanocomposite are dependent on the type of solvent used. The dielectric properties measured at a frequency of 1 kHz showed that acetone gives the highest dielectric constant and capacitance compared with toluene and THF. Toluene gives the lowest dielectric loss among the three. The topography and roughness of the PMMA:TiO 2 nanocomposite indicate that a particular solvent results in a different kind of surface morphology.
Dielectric behavior of Silica/Poly(dimethylsiloxane) nanocomposites. nano size effects
IOP Conference Series: Materials Science and Engineering, 2012
The enhancement of properties of elastomeric composite materials is very much dependent on the size and the surface modification of the reinforcing filler inclusions. It is well accepted that the reinforcement effects are primarily due to molecular interactions of the polymeric matrix and the filler inclusions and it involves both chemical and physical interactions.
Revue Roumaine de Chimie, 2021
In this study, a comparative study of nanocomposites with treated and untreated metal oxide nanoparticules using a plastograph was investigated. Stearic acid and co-mixing technique were chosen as a fast technique to ensure the dispersion of the filler into the polymeric matrix. Fillers were mechanically treated and co-mixed with stearic acid using kitchen coffee grinder and the mixture was then added to the polymeric matrix in a Brabender plastograph with various contents of 0.5 wt. %, 1 wt. % and 2 wt. %. The method effectiveness has been proved by AFM analysis. The results showed that the incorporation of inorganic semiconductor nanoparticles into polymeric matrix improves the dielectric properties. Results showed that with the co-mixing process and stearic acid the inorganic nanofillers have a strong influence on the permittivity of resulting nanocomposites.
Investigation of frequency dependent dielectric properties of polysiloxane – TiO2 nanocomposites
Journal of emerging technologies and innovative research, 2019
The polysiloxane – TiO2 nanocomposites were prepared by a solvent casting method in triethanolamine and tetrahydrofuran solvents. Fourier transform infrared spectroscopy for structural analysis and surface morphology was carried by scanning electron microscopy. The amorphous nature of polysiloxane observed in the amorphous nature of polysiloxane observed in XRD spectra. The surface morphology was studied by employing scanning electron microscopy and it is found that the nanoparticles are completely embedded in the polysiloxane. Further, the dielectric spectroscopy study reveals that the 0.3 wt % shows low dielectric constant and dielectric loss, as a result, it shows high conductivity of 1.35 х 10 4 S/cm. Among all the nanocomposites, 0.3 wt % of shows the lowest tangent loss value of 0.1 due to the non-debye’s type of relaxation process where the charge carriers are relaxed at the higher energy state for a longer time. The quality factor confirms that there is a small damping loss ...