Conducting Polymer Composites of Multiwalled Carbon Nanotube Filled Doped Polyaniline

A multiwalled carbon nanotube (c-MWNT)/polyaniline (PANI) composite was synthesized by an in situ chemical oxidative polymerization process. With the carbon nanotube loading increased from 0 to 30 wt %,, the conductivity also increased and became weakly temperature-dependent. Fourier transform infrared spectroscopy studies showed that the synthesis by an in situ process led to effective site-selective interactions between the quinoid ring of the PANI and the multiwalled nanotubes, facilitating charge-transfer processes between the two components. The morphological analysis indicated that the c-MWNTs were well dispersed and isolated, and the tubes became crowded proportionally to the weight percentage of c-MWNTs used in the composites. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 680-684, 200

Surface Modification and Characterization of Multi-Walled Carbon Nanotube

Multi-walled carbon nanotubes (MWCNTs) were chemically functionalized by using sulfuric acid and nitric acid. The functionalization was done with two different acid ratio. The functionalized nanotubes were characterized with Fourier Transform Infrared Spectroscopy, X-Ray Photon Spectroscopy, Thermal Gravimetric Analysis, Elemental Analysis, Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy. Sulfonation of carbon nanotubes (CN) increased the electrical conductivity of carbon nanotubes up to 1.25 x 10-1 S/cm. The SEM micrographs of the samples showed that CN was observed in more bulky form due to the increasing hyrogen bonding between the particles. The zeta potential of the CN increased with increasing sulfonation amount

Solution properties of polyaniline

Solution properties of polyaniline (PANI) synthesized at various temperatures were studied using static light scattering (SLS), intrinsic viscosity, and dynamic light scattering (DLS). We demonstrated that average radius of gyration (R-g), intrinsic viscosity [eta], and average hydrodynamic radius (R-H), of polyaniline molecules in dilute N-methyl-2-pyrrolidinone (NMP) solutions increased with decreasing synthesis temperatures, i.e.; increasing molecular weight. SLS data demonstrate that second virial coefficient (A(2)) decreased with increasing particle sizes suggesting that solubility of PANI in NMP decreased with increasing particle sizes. We also find that the polymers extend as the polymer concentration is lowered and that the increase in the hydrodynamic radius can be expressed by a power law of the electrostatic screening length. This behavior is typical of polyelectrolytes in dilute solution, providing a basis for understanding the conformation changes of this metallic polymer in solution. (C) 2009 Society of Chemical Industr

The influence of polymerization temperature on structure and properties of polyaniline

The influence of polymerization temperature (from -25 to +25 degrees C) on molecular weight, crystallinity, electrical conductivity, thermal and morphological properties of polyaniline has been investigated. Aniline was oxidized in an aqueous medium with ammonium persulfate and 1.0 M hydrochloric acid. The reaction mixture freezes below -10 degrees C and hence lithium chloride was used in sufficient amount to prevent freezing. As the reaction temperature decreases, both the molecular weight of polyaniline and its crystallinity increase. Thermal studies show a common three step decomposition pattern irrespective of the temperature used during synthesis. The morphology of polyaniline changes from granular (reaction in liquid medium) to tubular (polymerization in the frozen state). Thermal analysis indicated that the polyaniline stability increased with decreasing synthesis temperatures. Electrical conductivity of polyaniline was found to be independent of the polymerization temperature and, consequently, of the molecular weight

Synthesis and Characterization of Surface Modified Fullerene

Fullerenes were chemically functionalized by using sulphuric acid and nitric acid. The functionalization was done with two different acid ratio. The functionalized nanotubes were characterized with Fourier transform infrared spectroscopy and X-ray photonelectron spectroscopy (XPS), elemental analysis, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Sulfonation of fullerene increased the electrical conductivity of fullerenes up to 0.027 S/cm. TEM micrographs showed that sulfonation improves the dispersion of fullerene in water. Zeta potential measurements also proved this result

Electrical and Mechanical Properties of Polypropylene/Carbon Black Composites

Polypropylene(PP)/carbon black(CB) composites at different compositions were prepared via melt blending of PP with CB. The effect of CB content on mechanical and electrical properties was studied. Test samples were prepared by injection molding and compression molding techniques. The effect of processing type on mechanical and electrical properties was also investigated. Composites become semi-conductive by addition of 2wt% CB. The relation between mechanical and electrical properties was discussed. The influence of CB content on morphology and crystallinity was also studied

Synthesis and Characterization of Polypyrrole Nanoparticles and Their Nanocomposites with Poly(propylene)

Conducting polypyrrole (PPy) nanoparticles were synthesized via microemulsion polymerization. PP/PPy nanocomposites were prepared by melt-mixing of polypyrrole with polypropylene (PP) and processed with injection molding. Tensile tests have revealed that increasing amount of PPy increased the strength and the stiffness of the nanocomposite while limiting the elongation of PP. Thermal gravimetric analysis has showed that incorporation of PPy nanoparticles has improved the thermal stability of the nanocomposites. Increasing amount of PPy nanoparticles increases the conductivity of nonconductive PP up to 2,4.10(-4) Scm(-1). The same techniques were used to characterize nanocomposites containing 2% w dispersant. Composites prepared with dispersant have involved smaller dimension PPy nanoparticles and exhibited improvement in some mechanical and thermal properties

Characterization and Electrical Conductivity of Poly(ethylene glycol)/Polyacrylonitrile/Multiwalled Carbon Nanotube Composites

Polymer blends based on poly(ethylene glycol), polyacrylonitrile, and multiwalled carbon nanotubes (MWNTs) were prepared by the solvent cast technique from the dispersion of the MWNTs in the concentration range 0-3.45 wt %. The interaction of the MWNTs with the polymer blend was confirmed by a Fourier transform infrared (FTIR) spectroscopy study. The thermal properties of the polymer blend with the MWNTs were carried out by means of differential scanning calorimetry (DSC). It was evident from DSC that the polymer/MWNTs had a high thermal stability. Scanning electron microscopy was used to study the dispersion of the MWNTs in the polymer blend. To measure the electrical conductivity, the four-point probe method was used. The electrical conductivity showed an ionic conductivity on the order of 4.4 x 10(-4) to 1.2 x 10(-2) S/cm. Relative changes in the conductivity with the concentration and temperatures for the samples were analyzed. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 142-147, 201