Preparation Method Effect on Thermal properties of PMMA/Clay Nanocomposite

Nanocomposites of PMMA/clay with new natural montmorillonite, noted AC, (from Algeria) at different content of inorganics (1, 3 and 5 wt%) were prepared by either in situ bulk radical polymerization of monomer or by ultrasonic dispersion of clay with preformed PMMA. The organomodification was achieved by ion exchange of Na+ with hexadecyl trimethyl ammonium bromide (HDTMA). The dispersion degree of the nanofiller in the polymer matrix was evaluated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The thermal stability of nanocomposites, evaluated by thermogravimetrical analysis, was in accordance with the morphological of each system while their glass transition temperature, determined from differential scanning calorimetry (DSC), was not significantly influenced by the presence of nanofiller

Supramolecular approach for efficient processing of polylactide/starch nanocomposites

peer reviewe

Combining atom transfer radical polymerization and melt compounding for producing PMMA/clay nanocomposites

peer reviewe

Use of new natural clay to produce poly(methyl methacrylate)- based nanocomposites

peer reviewedNanocomposites of poly(methyl methacrylate) (PMMA) filled with 3 wt% of modified natural Algerian clay (AC; montmorillonite type) were prepared by either in situ polymerization of methyl methacrylate initiated by 2,2'-azobisisobutyronitrile or a melt-mixing process with preformed PMMA via twin-screw extrusion. The organo-modification of the AC montmorillonite was achieved by ion exchange of Na+ with octadecyldimethylhydroxyethylammonium bromide. Up to now, this AC montmorillonite has found applications only in the petroleum industry as a rheological additive for drilling muds and in water purification processes; its use as reinforcement in polymer matrices has not been reported yet. The modified clay was characterized using X-ray diffraction (XRD), which showed an important shift of the interlayer spacing after organo-modification. The degree of dispersion of the clay in the polymer matrix and the resulting morphology of nanocomposites were evaluated using XRD and transmission electron microscopy. The resulting intercalated PMMA nanocomposites were analysed using thermogravimetric analysis and differential scanning calorimetry. The glass transition temperature of the nanocomposites was not significantly influenced by the presence of the modified clay while the thermal stability was considerably improved compared to unfilled PMMA. This Algerian natural montmorillonite can serve as reinforcing nanofiller for polymer matrices and is of real interest for the fabrication of nanocomposite materials with improved properties

A new electrochemical sensor based on carbon paste electrode/Ru(III) complex for determination of nitrite: Electrochemical impedance and cyclic voltammetry measurements

International audienceThe modified carbon paste electrode with Ru(III) complex was studied as a novel sensor for the determination of nitrite. The behavior of NO2− at the electrode surface was investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). EIS provided useful information on the charge transfer resistance (R) at the electrode/solution. The EIS measurements showed that R is low at oxidation potentials, and decreases with increasing temperature. The increase of the constant phase element with temperature is due to the accumulation of nitrite on the electrode, thus, facilitating the electron transfer between electrode and NO2−. CV was used to study the effect of pH on the electro-catalytic oxidation of NO2− and to determine the limit of detection (LOD). CV measurements showed a good linear relationship between the oxidation current and the concentration of NO2− over a wide concentration range 0–1.38 × 10−2 mol L−1. Low detection limit of 1.39 × 10−6 mol L−1 toward NO2− was obtained. LOD decreased by 23.2% compared to that determined using cavity microelectrode. © 2016 Elsevier Lt