We report a ‘green’, simple and efficient approach for the production of graphene oxide (GO) by ultrasonic assisted electrochemical exfoliation of graphite rods, and by using Improved Hummers’ graphene oxide (IGO) as an electrolyte. The effects of applied bias, electrolyte concentration and the duration of the electrochemical exfoliation on the quality of the GO nanosheets were investigated. The produced graphene oxide with a high yield (> 48%), and the lowest defect was obtained in the ultrasonic assisted electrochemical exfoliation performed at 0.05% IGO mass percent in DI water and 50 V applied bias for 1 hour at room temperature. The structural, morphological and physical properties of the obtained nanostructures were analyzed by XRD, Raman, FESEM, STEM techniques and thermal conductivity analysis, respectively. The characteristic Raman bands were observed at 1354 cm-1 and 1590 cm-1 for the prepared GO nanosheets. The produced graphene oxides exhibited a lateral dimension of 3-7 μm revealed by field emission scanning electron microscopy (FESEM). It was observed that the thermal conductivity enhancement of 14.95% was obtained for GO, which was higher than the other IGO nanofluid (7.64%) with respect to DI water at 20oC.
The conductive composite material obtained by using a conductive polymer and an inorganic layered clay. • The increase of microhardness in the composite material with the help of synergetic effects of its components. • The rise of thermal stability in POA polymer after the incorporation of talc to the composite material. Purpose: The purpose of the research is to prepare a conductive POA/talc composite using conducting poly(oanisidine) and layered talc clay in the presence of ammonium persulfate as oxidant. After preparation of the composite a new material with improved properties such as elastic-plastic property and thermal properties was obtained. Theory and Methods: Conductive POA/Talc composite was prepared via the chemical polymerization of o-anisidine in the presence of talc particles by using ammonium persulfate as oxidant. 1.0 M aqueous HCl solution (17 mL) was first added onto talc (1.0±0.001 g) and o-anisidine in a beaker and then the suspension was mixed for about 15 min. The polymerization was initiated by the addition of aqueous acidic oxidant solution (3 mL) into the mixture. After 2 hours of the polymerization, the mixture was first separated by centrifugation at 1000 rpm and then washed by distilled water, methyl alcohol and dilute HCl solution, in sequence, to remove unreacted monomer and oxidant from the composite, as well as to recover dopant anions. As the final step, the composite was dried at 50 o C for 24 h under vacuum. Results: The polymerization parameters such as the effect of APS/o-anisidine mole ratio and the effect of o-anisidine concentration on the conductivity and POA amount of the POA/talc composite were investigated. The structural, morphological and thermal properties of the composite were analyzed by using XRD (X-ray Diffraction), FTIR (Fourier Transform InfraRed spectroscopy) and TGA (Thermogravimetric Analysis) techniques; micro-hardness measurement, BET (Brunauer-Emmett-Teller) surface area analysis and SEM (Scanning Electron Microscopy) analyses. TGA showed that the thermal stability of the conducting polymer POA increased by the formation of the composite structure with talc clay. Conclusion: A POA/talc composite with a POA content of 42.7% and a conductivity of 3.2x10-5 S/cm was obtained through the polymerization conditions of 0.2 M o-anisidine concentration, 1,5 APS/o-anisidin mole ratio and 0.1 M HCl concentration over 2 hours at 20 o C. Micro-indentation analysis indicated that the micro-hardness property of the talc particles increased after the addition of the conducting polymer to the composite. The coating of the conducting POA polymer on the talc surfaces was confirmed by the stable places of the peaks in the XRD patterns and the micrographics in SEM microstructures.
In this study, Deadbeat control of a jacketed batch reactor in which styrene polymerization occurs under isothermal conditions has been investigated experimentally and by simulation to achieve a specific constant number average chain length and conversion in a minimum time. It was founded that Deadbeat control provided a good performance in maintaining the reactor temperature at its set point at the isothermal conditions. It is obtained that desired final conversion and number average chain length values were almost achieved.
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