Ashok Kumar Sharma; Preetam Bhardwaj; Sundeep Kumar Dhawan; Yashpal Sharma
Abstract
A novel study on conducting polymers based composites involving hybrid carbon nanostructure assemblage of graphene, amine functionalized multiwalled carbon nanotubes and poly(aniline-co-pyrrole) has been done. The composites were synthesized by oxidative polymerization of 1:1 mixture of aniline and pyrrole ...
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A novel study on conducting polymers based composites involving hybrid carbon nanostructure assemblage of graphene, amine functionalized multiwalled carbon nanotubes and poly(aniline-co-pyrrole) has been done. The composites were synthesized by oxidative polymerization of 1:1 mixture of aniline and pyrrole monomer with ammonium per sulphate and ferric chloride oxidants. UV-vis Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR) and Raman Spectroscopy were used to identify the chemical structure of the obtained composites. Thermal studies indicate that the composites are stable in comparison to poly (aniline-co-pyrrole) alone showing that the hybrid carbon assemblage contributes towards thermal stability in the composites. Crystalline properties of the composites were investigated by X-ray diffraction (XRD). Scanning electron microscopy (SEM) was used to characterize the surface morphology of the composites. The specific capacitance of the composites was characterized by cyclic voltammogram (CV). The capacitive studies reveal that the composite has synergistic effect and highest specific capacitance of 337.35F/g at scan rate of 10mV/sec and 193.06F/g at scan rate of 50 mV/sec was obtained for the composite having thinnest layer of co-polymer over hybrid carbon assemblage i.e., 02-PANI-co-PPY-C.
N.K. Singh; Pritam Kumar; Radheshyam Rai
Abstract
Dielectric properties of (1-x)Ba(Fe0.5Nb0.5)O3-xBaTiO3 (where x = 0.00, 0.05 and 0.10) solid solution ceramics at high temperature range of RT ~ 270 o C have been characterized in this paper. The above said polycrystalline ceramics with (x = 0.0, 0.05 and 0.10) have been produced via a mixed oxide route. ...
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Dielectric properties of (1-x)Ba(Fe0.5Nb0.5)O3-xBaTiO3 (where x = 0.00, 0.05 and 0.10) solid solution ceramics at high temperature range of RT ~ 270 o C have been characterized in this paper. The above said polycrystalline ceramics with (x = 0.0, 0.05 and 0.10) have been produced via a mixed oxide route. The effects of BaTiO3 substitution on the structure and on the electrical and ferroelectric properties of Ba(Fe0.5Nb0.5)O3 samples have been studied by performing x-ray diffraction and dielectric measurements. The dielectric properties (e¢ and tan d) were investigated in the temperature range of 30-270 °C and in the frequency range of 100 Hz-5 MHz. The variation of relative dielectric permittivity (tan d) and tangent loss (tan d) has suggested a significant role of hopping of trapped charge carriers, which is resulted in an extra dielectric response in addition to the dipole response. It is observed that: (i) the relative dielectric permittivity and tangent loss (tan d) are dependent on frequency, (ii) the temperature of dielectric permittivity maximum shifts toward lower temperature side and (iii) dielectric permittivity and tangent loss rapidly increase by making solid solution of BFN with BaTiO3. X-ray diffraction analysis of the compound suggests the formation of single-phase compound with monoclinic structure. SEM photographs exhibit the uniform distribution of grains. The maximum ferroelectric transition temperature (Tc) of this system was 250-270 °C with the dielectric constant peak of 72500 at 1.09 kHz for x = 0.05.
Rajendra Kumar Goyal;Amol Kadam
Abstract
Electrical properties of graphite flake (GF) filled polyphenylene sulphide (PPS) composites prepared by hot pressing was investigated to be used for electromagnetic interference (EMI) shielding applications. Composites exhibited an electrical conductivity percolation threshold of 5 wt%. The electrical ...
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Electrical properties of graphite flake (GF) filled polyphenylene sulphide (PPS) composites prepared by hot pressing was investigated to be used for electromagnetic interference (EMI) shielding applications. Composites exhibited an electrical conductivity percolation threshold of 5 wt%. The electrical conductivity of composites was increased fourteen orders of magnitude higher than that of pure PPS. The dielectric constants and dissipation factor of composites were measured in a frequency range of 100 KHz to 15 MHz. The dielectric constant of the composites increased several orders of magnitude and showed a strong dependence on frequencies. For example, dielectric constant of 8 wt% composite measured at 1 MHz was increased by five orders of magnitude compared to pure PPS. Similarly, dissipation factor was increased significantly. Scanning electron microscopy showed 3-dimensional conducting network of GF across the PPS matrix. Significant improvement in electrical properties shows that these composites may be useful for EMI shielding particularly at high temperature applications.