Synthesis and characterization of conducting composites of polyaniline and carbon black with high thermal stability

Abstract

nanotubes substrates have demonstrated some properties such as the increase of the PANI conducting ability [27,32,33] , the supercapacitive behavior [30,34] as well as better recovering properties by functionalizing the oxidized carbon nanotube with p-phenylenediamineamino before starting the polymerization [35] . Nevertheless, the attainment of a well controlled carbon nanotube substrate, with high purity degree, is still difficult and expensive.In this work, a detailed and simple route is described to prepare composites based on the direct chemical polymerization of PANI onto particles of conductive CB substrate (type Printex ® L6 from Degussa S.A). It is also demonstrated that this procedure presents great advantages such as the best control in the substrate recovering. The composites were characterized by thermal analysis, specific area, elemental analysis and AC conductivity. ExperimentalAniline (Aldrich) was purified by distillation under reduced pressure in the presence of zinc powder. Conductive CB Printex ® L6 (10 -1 S cm -1 in pressed samples) was purchased from Degussa. All reagents were analytical grade and used as received. The water used for the solutions was purified by the Milli-Q system (Millipore Inc.).The PANI was synthesized using aqueous HCl by the direct oxidation of the aniline with the addition of a solution of 0.25 M (NH 4 ) 2 S 2 O 8 using a monomer:oxidant molar ratio of 4:1 at 0 °C. The resulting PANI powder was dried under air atmosphere at 60 °C.The composites were prepared by maintaining CB under mechanical stirring for 1 hour in contact with acidic aqueous solutions of 1.0 M aniline in 1.0 M HCl. After that, the solution of 0.25 M (NH 4 ) 2 S 2 O 8 in 1.0 M HCl was drop wise IntroductionPANI presents very poor mechanical stability in its conducting state, which requires the preparation of copolymers or blends. Moreover, the polymer must be stable at the high temperatures that are necessary for processing [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] . However, films prepared with intrinsically conducting polymers (ICPs) exhibit poor mechanical properties and are also thermally unstable [17,18] , for example, conducting PANI loses its electrical properties at 225 °C, even under nitrogen atmosphere.Generally, thermoplastics or thermosets conductive compounds are obtained by the addition of a conductive loading, such as CB, to the polymeric matrix. Additionally, to obtain suitable materials, high loadings of the additive are necessary. This makes heat processing difficult, because the high surface area additive increases the melt viscosity in the interaction with the polymer matrix [19,20] .Composites obtained by deposition of ICPs over CB particles, showed thermal stability and effective reduction of the surface area and pore volume of the CB [18,21] . These classes of composites could be obtained by the in situ deposition of the ICP on CB substrate [18,22] , the direct polymerization of ICPs on carbon substrates, by chemical [23,21,24] or electrochemical method [25][26][2...

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Effect of networked hybridized nanoparticle reinforcement on the thermal conductivity and mechanical properties of natural rubber composites

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Cashew nut shell liquid, a valuable raw material for generating semiconductive polyaniline nanofibers

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