Ezzeddine Srasra

Electrical and dielectric properties of polyaniline and polyaniline/montmorillonite nanocomposite prepared by solid reaction using spectroscopy impedance

The combination of two components with uniform distribution in nanoscale is expected to facilitate wider applications of the material. In this study, polyaniline (PAn) and polyaniline/montmorillonite (Mt) nanocomposite were prepared by solid reaction using persulfate of ammonium as oxidant. The phase composition and morphology of the nanocomposite were characterized by FTIR, UV-visible spectroscopy, X-ray diffractometer, thermal gravimetric analysis, and scanning electron microscopy. The electrical and dielectric properties were determined using spectroscopy impedance. The analysis of UV-visible and FTIR spectroscopy demonstrated that aniline chloride has been polymerized into PAn in its conducting emeraldine form. Thermogravimetric analysis suggested that PAn chains intercalated in the clay host are more thermally stable than those of free PAn prepared by solid-solid reaction. Electrical measurements were carried out using the complex impedance technique in the frequency range of 10-2 to 104 Hz at different temperatures. The ac conductivity data of different nanocomposites were analyzed as a function of frequency and temperature. It has been found that the incorporation of inorganic clay phase into polyaniline matrix has an effect on the electrical and dielectric properties of the nanomaterial.

Spectroscopic Study of Polyaniline/AgCl@Ag Nanocomposites Prepared by a One-Step Method

Polyaniline (PANI)/Ag@AgCl nanocomposites were successfully synthesized by one-step method, which consists of mixing aqueous solutions of silver nitrate with aniline chloride and delaying the evolution of reaction. By this way, aniline chloride represents a monomer for PANI and a source of Cl− anions necessary for the formation of AgCl, and silver nitrate acts simultaneously as oxidant initiator for aniline polymerization and precursor for AgCl@Ag phase. The formation of polyaniline has been identified by the change of color to black green and from RAMAN and FTIR spectroscopy while AgCl@Ag phase has been highlighted from XRD and RAMAN. The application of Debye–Scherrer theory allows us to measure the crystallite sizes of Ag and AgCl which were, respectively, 23 and 52 nm. The AC conductivity showed a regime of constant DC conductivity at low frequencies corresponding to 0.4 S/cm−1 and a crossover to a frequency-dependent regime of the type Aωs at high frequencies.

Unsaturated polyester-nanoclay nanocomposite coatings for effective corrosion protection of steel

Polymeric composites are widely used to control the corrosion of metal surfaces. Various types of polymer nanocomposites provide better corrosion protection than the neat resins. This paper aims at reviewing some of the protective properties of Tunisian clay (montmorillonite-MMT)/unsaturated polyester (UP/MMT) in 3.5% NaCl. The spin coating technique is applied on metals deposited on a stainless steel surface. The samples are characterized with XRD, TEM and SEM methods. The corrosion performance was estimated by using open circuit potential, polarization measurements and electrochemical impedance spectroscopy. The UP/OMMT nanocomposites showed the best corrosion protection performance.