Browsing by Subject "ZINC BORATE"

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    DISSOLUTION KINETICS OF SMITHSONITE IN BORIC ACID SOLUTIONS
    (OFICYNA WYDAWNICZA POLITECHNIKI WROCLAWSKIEJ) Abali, Y; Bayca, SU; Gumus, R
    The dissolution of smithsonite in boric acid solutions was investigated. The influence of the reaction temperature, acid concentration, solid-to-liquid ratio, particle size and stirring speed on the zinc extraction were determined in the experiments. The results show that the dissolution rate increases with increasing acid concentration and reaction temperature, and with decreasing particle size and solid-to-liquid ratio. The dissolution results were analyzed by reaction control models. The activation energy of smithsonite in boric acid solution was also calculated.
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    Preparation, characterization and thermal properties of polypropylene/polyethylene/zinc borate composites: investigation of thermal degradation kinetics
    (SPRINGER) Saltan, F; Sentuerk, S; Al, AM; Oezkan, AN; Sirin, K
    In this study, polypropylene/polyethylene/zincborate composites (PP/HDPE/Zinc Borate) were prepared using high-density polyethylene, isotactic polypropylene, and a certain percentage of zinc borate. The composites were characterized using by X-Ray Diffraction (XRD), Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDX), Fourier Transform Infrared (FT-IR) spectroscopy analyses. The thermal behavior of the materials was investigated using thermogravimetric analysis (TG), Differential Thermal Analysis (DTA), and Differential Thermogravimetry (DTG). The thermal degradation kinetics of the PP/HDPE/Zinc Borate15% composite was investigated. The apparent activation energies (Ea) were obtained following the differential and integral methods of Kissenger and Flynn-Wall-Ozawa (FWO). Using Kissinger's and Flynn-Wall-Ozawa methods to define thermal degradation of PP/HDPE/Zinc Borate%15, their activation energies were 233.3 kJ/mol and 189.3 kJ/mol, respectively. The mechanism of the studied conversion range was found to be the R3 deceleration model using the Coats-Redfern. The viscosity and shear stress of PP/HDPE/Zinc Borate15% were determined using a cone-plate type rheometer. PP/HDPE/Zinc Borate15% composite shows plastic-type fluidity, according to rheological analysis.
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    Thermoluminescence spectra of Tm doped ZnB2O4 phosphor prepared via a wet-chemical synthesis
    (PERGAMON-ELSEVIER SCIENCE LTD) Bulcar, K; Kucuk, N; Topaksu, M; Can, N
    In this paper we describe the thermoluminescence (TL) characteristics of 0.8 mol% Tm3+ doped ZnB2O4 phosphors prepared by a wet-chemical method. The TL glow curves of the phosphor sample consisted of three peaks located at 181 degrees C, 213 degrees C and 351 degrees C. The glow peak TL temperature (T-m) at which the TL glow peak occurs shifts toward the higher temperature side whilst the heating ramp rate increases and also the peak TL intensity (I-m) decreases. The TL glow curves are characterized by evaluating various dosimetric characteristics of scrutinized samples. The T-m - T-stop investigations on regenerated TL signals revealed that there are five different traps in the phosphor with energy values in the range of 0.61-1.71 eV. The dose responses increased in a linear way for 3 peaks with the beta-ray exposure in the dose range of 0.11-60 Gy. The process of applying 10 Gy dose was repeated for ten successive irradiation cycles to check reproducibility and the maximum variation was found to be less than 1% from the average value. These results provide valuable knowledge for use of the characteristics of T-m doped ZnB2O4 in dosimetry research.