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Fattoum A.,Unit of Research Materials Environment and Energy 06 UR 12 01
Journal of Physics D: Applied Physics | Year: 2011

The effects of the action of hydrogen peroxide (H 2O 2) as an oxidizing agent on the electrical properties of polyaniline-aluminium (PANI-Al) composites are studied. Direct current (dc) electrical conductivity is investigated in the temperature range 303-453 K. A decrease in the conductivity with attack time is observed. The results are compatible with UV-visible and infrared absorption measurements and scanning electron microscopy analysis. The experimental data show a transition from a negative temperature coefficient of resistivity (TCR) to a positive TCR. This transition becomes more pronounced when the attack time increases. Depending on the H 2O 2 attack time, we found that the dc conductivity of the composites is described by two distinct models: the first is a series combination between the fluctuation-induced tunnelling (FIT) model with a metallic transport model, the second is a combination between Mott's three-dimensional variable range hopping with an intrinsic metallic model. The different FIT and Mott parameters are evaluated. The change in the conduction mechanism is attributed to the disorder and the localization effect caused by the action of H 2O 2 on the PANI-Al composite. © 2011 IOP Publishing Ltd. Source


Fattoum A.,Unit of Research Materials Environment and Energy 06 UR 12 01 | Ben Othman Z.,Laboratoire Of Materiaux Composites Et Polymeres Lamacop | Arous M.,Laboratoire Of Materiaux Composites Et Polymeres Lamacop
Materials Chemistry and Physics | Year: 2012

In this work we present results of thermal spectral and conductivity studies on polyaniline/poly (methylmethacrylate) composite films with polyaniline Wt% situated under the percolation threshold. The glass transition temperature Tg is significantly modified by the presence of polyaniline. For polyaniline Wt% not exceeding 0.3%, the Tg decreases, but for specimens having highest amounts it increases. The Uv-Visible absorption spectroscopy indicates the presence of characteristic absorption bands of polyaniline. When the amount of polyaniline is increased from 0% to 0.5%, the dc conductivity shows an increase with a maximum attained at about 0.1% followed by a decrease. A correlation with the variation of Tg in this domain of polyaniline concentration is proposed. © 2012 Elsevier B.V. All rights reserved. Source


Mhamdi M.,Unit of Research Materials Environment and Energy 06 UR 12 01 | Mhamdi M.,University of Carthage | Elaloui E.,Unit of Research Materials Environment and Energy 06 UR 12 01 | Trabelsi-Ayadi M.,University of Carthage
Industrial Crops and Products | Year: 2013

The metal adsorption by clays is widely studied. The classical method consists in mixing a volume of metal solution with a mass of clay and making a series of agitation and centrifugation. The supernatant is analyzed by an atomic absorption method to determine the concentration adsorbed by clay. But this method has several disadvantages as the extract may contain impurities which are suspensions that can yield wrong analysis results. This work aims at studying the influence of a new method that uses membrane filtration to determine the maximum amount of zinc adsorbed by clay. To prove the effectiveness of such method, several identification techniques are used. The local clay extracted from Oued Tfal south west Tunisia, has been characterized. The mineralogical and chemical compositions of the materials have been determined. Gives the adsorption of Zn(II) studies, experimental data demonstrated a high regression coefficients with the pseudo-second order kinetics. The equilibrium data showed the best most suitable model fit to Freundlich and Langmuir models. © 2013. Source


Mhamdi M.,Unit of Research Materials Environment and Energy 06 UR 12 01 | Mhamdi M.,University of Carthage | Gasmi N.,University of Carthage | Elaloui E.,Unit of Research Materials Environment and Energy 06 UR 12 01 | And 2 more authors.
IOP Conference Series: Materials Science and Engineering | Year: 2010

The correlation between physicochemical properties and mechanical behavior of clays is the subject of many studies [1,2]. The mechanical properties of clays are particularly significant insofar as they involve several disciplines, remediation, drilling muds, civil engineering, storage of toxic and radioactive waste. The smectite used in this work is from the southern west of Tunisia, particularly from Oued Tfal near the town of Gafsa is noted OT. Work included action on the characterization, physicochemical and mechanical properties of the raw clay treated with hydrochloric acid and purified. This work aims at studying the influence of pure clay fraction, including compensating cations on the hydromechanical properties of clay. The thermal study sample gives a percentage of 32.5% of carbonate in the raw clay. The elimination of carbonates by acid attack controlled the following results: If treatment by 0.5M represents a departure total of carbonates, there are probably altered layers of the clay fraction. To eliminate the excess of carbonate (6.03%), the sample was treated by 0.4 M HCl without deterioration of the structure of the silicate fraction. The hydromechanical study of three samples of raw clay (OT) purified (OTNa) and treated by (0.4M) hydrochloric acid put it clearly the relationship between the cation exchange capacity the percentage of carbonate and the swelling pressure. © 2010 IOP Publishing Ltd. Source


Mhamdi M.,Unit of Research Materials Environment and Energy 06 UR 12 01 | Mhamdi M.,University of Carthage | Gasmi N.,University of Carthage | Elaloui E.,Unit of Research Materials Environment and Energy 06 UR 12 01 | And 2 more authors.
IOP Conference Series: Materials Science and Engineering | Year: 2010

This work shows the results of various analysis on a representative clay sample from southern west of Tunisia, particularly from Oued Tfal near the town of Gafsa. The raw smectite contains some carbonate, quartz, chlorite, and anorthite. During the attack of the carbonate clay with a solution of hydrochloric acid, a change of the chemical composition and physical properties was observed. This change is dependent on several factors: the initial concentration of the acid, the nature of the clay, the ratio acid / clay⋯). Although treatment to 0.5 M represents a total removal of carbonates, there are probably altered layers of the clay fraction. The result shows that for a treatment with acid solutions of concentrations below 0.5 M there is gradual removal of carbonate without protonation of the clay layers. The characterization of the clay fraction shows that the sodium clay purified (OTNa) consists of a sodium montmorillonite smectite. The cation exchange capacity and the specific surface of OTNa measured using the method of methylene blue are equal to 82 meq/100g and 667 m2 / g respectively. © 2010 IOP Publishing Ltd. Source

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