Browsing by Subject "Clay minerals"
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Item Open Access Poly(epsilon caprolactone)/clay nanocomposites via host-guest chemistry(Elsevier Ltd, 2015) Arslan, M.; Tasdelen, M. A.; Uyar, Tamer; Yagci, Y.Cyclodextrin-modified montmorillonite (MMT-CD) has been prepared from commercial montmorillonite clay (Closite 30B) containing two hydroxyl groups by reacting succinic anhydride through esterification. Poly(epsilon caprolactone) (PCL)/clay nanocomposites are prepared by host-guest chemistry between MMT-CD as host and PCL, hydrophobic polymer as guest. The structures of the intermediates and final nanocomposite are investigated in detail by FT-IR XRD, TEM, DSC and TGA measurements. The intercalated/exfoliated morphologies are determined by combined XRD and TEM analyses. Thermal stabilities of all nanocomposites are improved by the addition of MMT-CD compared to the neat polymer. The DSC data confirm that the crystallinity of PCL is slightly increased by increasing clay loading. © 2015 Elsevier Ltd. All rights reserved.Item Open Access Preparation of fluorinated methacrylate/clay nanocomposite via in-situ polymerization: characterization, structure, and properties(John Wiley and Sons Inc., 2016) Karamane, M.; Raihane, M.; Tasdelen, M. A.; Uyar, Tamer; Lahcini, M.; Ilsouk, M.; Yagci Y.Novel fluorinated coating containing well-dispersed silicate nanolayers is successfully produced via in-situ free radical polymerization of 2,2,2-trifluoroethyl methacrylate in the presence of vinylbenzyl-functionalized montmorillonite with different loading. The organic modification of sodium montmorillonite is achieved through an ion exchange reaction with triphenylvinylbenzylphosphonium chloride as surfactant prepared before use by reaction with vinylbenyl chloride and phosphine. The following in-situ polymerization in the presence of organomodified clay leads to fluorinated nanocomposites with of partially exfoliated and intercalated morphologies, as determined via XRD and TEM analysis. The nanoscale dispersion of clay layers is also evidenced by thermal analysis; a moderate decrease of the glass transition temperature about 2–8 °C compared to their virgin PMATRIF and an improvement of their thermal stability as evidenced by TGA. The wettability of the nanocomposite films is also studied by contact angle measurements with water. The incorporation of organomodified clays not only increases the hydrophobicity of the fluorinated polymers but also improves the surface properties of obtained nanocomposites. Compared the virgin homopolymer, the mechanical properties of the nanocomposites are reduced by addition of organomodifed clay at temperature from 30 to 60 °C, whereas this trend is gradually decreased at higher temperature.Item Open Access Sorption behavior of radioiodine on organic rich soil, alumina and clay minerals(Bilkent University, 1992) Assemi, ShoelehSorption behavior of radioiodine on organic rich soil, alumina, chlorite- illite clay mixture, kaolinite and bentonite have bc;en studied using the batch method. was used as tracer. Characterization of samples were done by FTIR, X-ray diffraction spectrometry and particle size distribution by Andreason pipette method. The grain size of the samples used were all below 38/xm and the experiments were performed at room temperature. The aqxreos phase used in all experiments were synthetic ground water with a composition similar to the underground waters of the regions where the samples were obtained. Stock solutions containing tracer, were prepared using synthetic ground- water. Initial concentration of inactive iodide ion in the solutions ranged from 10~®to 10“^ mmole/ml. The influence of contact time, solution/solid ratio, pH of synthetic ground- water, biomass of soil and I~ ion concentration on the sorption of radioiodine on the organic rich soil were investigated. The effect of I~ ion concentration and complexing agents on the sorption behavior of radioiodine on alumina and clay minerals were also studied. A rather slow kinetics was observed for tlie adsor])tion of radioiodine on the organic rich soil, tending saturation within 14 da.ys. It was observed that distribution ratio increased with increasing ratio of the volume of solution to the mass of soil(V/m ratio) and reached a platee.u after V/m=50. Distribution ratio did not change very much by changing the pH of the solution. Comparison of Eh-pH behavior of the solutions with the standard Eh-pH graph of iodine-water system indicated that in the whole pH rcinge, iodine is mostly preseirt in I~ form. To observe the effect of soil biomass soil samples were sterilized by heat and gamma-ray source and the results were found to be much lower than the control sample. Increasing the concentration of iodide ion in the .solution, caused a decrease in Rd. values. Desorption Wcvs ol)served only for low initial iodine concentrations < 1 X I0~^7nmol/ml), for organic rich soil which suggests that at least two sites and/or mechanisms are involved in the sorption. The sorption data were fitted to Freundlich and Dubinin-Radushkevich isotherms. The slope of Freundlich isotherm was found to be less than 1 which indicates the non-linearity of the isotherm. The mean free energy of adsorption was calculated from the slope of Dubinin-Radushkevich isotherm and was found as about 11 k.J/mol. The distribution of sites on organic rich soil was calculated using the Freundlich and Dubinin-Radushkevich constants, considering Cl~ as the competing ion with I~ in the solution. The affinities of sites were found to be about three times higher for Cl~ than I~. Among the clay minerals, the highest Rd value was found for chlorite-illite cla}^ mixture but tlie Rd values found for alumina and the other sanrples were well below those found for the organic rich soil. The sorption data were fitted to Freundlich and Dubinin-Radushkevich isotherms. All the Freundlich isotherms were non-linear (slope