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Basavaraja, C.,Pierson, R.,Huh, Do-Sung,Venkataraman, A.,Basavaraja, S. The Polymer Society of Korea 2009 Macromolecular Research Vol.17 No.8
Two types of nano composite were obtained by in situ chemical method in polyaniline (PANI)/dodecyl-benzenesulfonic acid (DBSA) system depending on the use of either ammonium persulfate (APS) or ferric chloride ($FeCl_3$) as the oxidant. In order to study the difference of the two composites in the surface characteristics, thermal stability, and electric properties, the composite films were studied by transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and temperature dependent DC electrical conductivity. The results revealed a large difference in the surface morphology, thermal stability, and the microstructure properties between the two composites, and these differences were considered responsible for the molecular order and conductivity.
Thermal Stimulated Conductivity in Cellulose Triacetate-Multiwalled Carbon Nanotube Polymer Films
Basavaraja, C.,Jo, Eun-Ae,Kim, Bong-Sung,Huh, Do-Sung Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.8
This paper describes the preparation and study of thermally stimulated discharge conductivity (TSDC) study of cellulose triacetate (CTA) - multiwalled carbon nanotubes (MWNTs) film thermoelectrets. TSDC has been carried out in the temperature range 308 - 503 K and at four different polarizing fields. The conductivity of the polymer blends increased with increase in temperature showing a semi-conducting behavior. The apparent activation energy also showed a pronounced effect with the increase in the content of MWNTs.
AC Conductivity Studies of Polyaniline-polymannuronate Nanocomposites
Basavaraja, C.,Kim, Na-Ri,Jo, Eun-Ae,Pierson, R.,Huh, Do-Sung Korean Chemical Society 2009 Bulletin of the Korean Chemical Society Vol.30 No.7
Temperature and frequency dependent AC conductivity behavior has been studied for the chemically synthesized polyaniline-polymannuronate (PANI-PM) composites. The temperature (300 - 500 K) and frequency (100 - $10^6$ Hz) dependent AC conductivity suggests evidence for the transport mechanism in PANI-PM composites. The frequency dependence of AC conductivity has been investigated by the power law. The frequency exponent (s) is determined, and the data suggest that s decreases with temperature. The variation of s with temperature suggests that AC conduction is due to the correlated barrier hopping.
Microwave absorption of poly‐<i>N</i>‐vinylcarbazole–polyaniline composites
Basavaraja, C.,Jo, Eun Ae,Kim, Bong Seong,Kim, Dae Gun,Huh, Do Sung Wiley Subscription Services, Inc., A Wiley Company 2011 Polymer engineering and science Vol.51 No.1
<P><B>Abstract</B></P><P>Poly‐<I>N</I>‐vinylcarbazole–polyaniline (PANI) composites were synthesized using different loading concentration of aniline (0.025–0.1 M) for their microwave absorption characteristics. The obtained composites were studied by Fourier transform infrared spectroscopy, thermogravimetric analysis technique, and atomic force microscope for their chemical structure, thermal stability, and the surface modifications, respectively. The conductivity increased much with the increase of aniline concentration in the composites. The composite sheets exhibited a strong microwave absorption in the microwave range of 1–10 GHz and achieved a maximum absorption value of 33 dB. The position of absorbing peak shows a mixed trend moving from lower to higher and again to lower with an increasing the concentration of aniline in the poly‐<I>N</I>‐vinylcarbazole–PANI. The new polymer composite exhibited an appreciable electromagnetic interference shielding efficiency compared with the previously reported PANI composites. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers</P>
Basavaraja, C.,Kim, Dae-Gun,Kim, Won-Jeong,Kim, Ji-Hyun,Huh, Do-Sung Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.3
Conducting polyaniline-poly($\varepsilon$-caprolactone) polymer composites were synthesized via in situ deposition techniques. By dissolving different weight percentages of poly($\varepsilon$-caprolactone) (PCL) (10%, 20%, 30%, 40%, and 50%), the oxidative polymerization of aniline was achieved using ammonium persulfate as an oxidant. FTIR, UV-vis spectra, and X-ray diffraction studies support a strong interaction between polyaniline (PANI) and PCL. Structural morphology of the PANI-PCL polymer composites was studied using scanned electron microscopy (SEM) and transmittance electron microscopy (TEM), and thermal stability was analyzed by thermogravimetric analysis (TGA) technique. The temperature-dependent DC conductivity of PANI-PCL polymer composite films was studied in the range of 305-475 K, which revealed a semiconducting behavior in the transport properties of the polymer films. Conductivity increased with the increase of PCL in below critical level, however conductivity of the polymer film was decreased with increase of PCL concentration higher than the critical value.
Basavaraja, C.,Choi, Young-Min,Park, Hyun-Tae,Huh, Do-Sung,Lee, Jae-Wook,Revanasiddappa, M.,Raghavendra, S.C.,Khasim, S.,Vishnuvardhan, T.K. Korean Chemical Society 2007 Bulletin of the Korean Chemical Society Vol.28 No.7
Conducting Polypyrrole-lead titanate (PPy/PbTiO3) composites have been prepared by in situ deposition technique by placing different wt.% of fine grade powder of PbTiO3 (10, 20, 30, 40, and 50%) during polymerization of pyrrole. The composites formed were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA), and these data indicate that PbTiO3 particles are dominating with an increase in crystallinity as well as thermal stability of the composites. The results on the low frequency dielectric studies which are obtained in the form of pressed pellet state are interpreted in terms of Maxwell Wagner polarization, which are responsible for the dielectric relaxation mechanism and frequency dependence of conductivity.
Basavaraja, C.,Kim, Won Jung,Kim, Dae Gun,Thin, P.X.,Huh, Do Sung Wiley Subscription Services, Inc., A Wiley Company 2011 Polymer composites Vol.32 No.7
<P><B>Abstract</B></P><P>A composite of poly(<I>N</I>‐vinylcarbazole) (PVK) containing gold nanoparticles (GNPs) was synthesized via simple solid‐state <I>in situ</I> bulk polymerization of <I>N</I>‐vinylcarbazole in the presence of GNPs at a high temperature. Both PVK and PVK–GNP composites were characterized by Fourier transform infrared (FTIR) and UV–vis spectroscopy. The surface morphology of the composites was studied by scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy, and transmission electron microscopy (TEM). Thermal stability was identified via thermogravimetric analysis. The composites were fabricated into films using the Langmuir–Schaefer process. The enhancement in the characteristics of room temperature I–V, pressure–area isotherms, and photoelectrochemical behaviors was observed in the composite films. Results suggest that a charge transfer process occurs across the hybrid at the interface of the PVK–GNP composites. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers</P>
Basavaraja, C.,Jo, Eun Ae,Kim, Bong Seong,Huh, Do Sung Wiley Subscription Services, Inc., A Wiley Company 2011 Polymer composites Vol.32 No.3
<P><B>Abstract</B></P><P>Cellulose triacetate (CTA) and multiwalled carbon nanotube (MWNT) composite films were prepared by dispersing different weight percentages of MWNTs into a CTA solution. These composite blends were characterized by UV–vis spectroscopy (UV), and their surface mophology, thermal stability, and amended crystallinity were determined by atomic force microscopy (AFM), thermogravimetric analysis (TGA), and X‐ray diffraction (XRD), respectively. Measurements of the complex impedance of the composite samples were made in the form of films. Sheets prepared from conventional techniques were used to study microwave absorption in the microwave range of 2–12 GHz, and the effects of sample thickness on microwave absorption were investigated. The experimental results show that the electrical conductivity of composites increases with the increase in MWNT loading without a percolation threshold. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers</P>