Papers by Keyword: DSC Analysis

Abstract: Benzhydrol derivatives 2a-c were synthesized, and evaluated for antituberculosis activities. These compounds were prepared from corresponding phenyl benzoates through Fries rearrangement and reduction reaction. Fries rearrangement reaction was chosen to use due to its convenient non-solvent method for synthesis. In order to determine the effective temperature for Fries rearrangement reaction, the reaction mixtures of phenyl benzoates 4a-c and AlCl₃ heated at constant rates were studied using DSC analysis. DSC curves of those mixtures showed that the reactions started at endothermic temperature ranging from 130 to 140 °C. The optimum temperatures for the synthesis of Fries rearrangement products 5a-c with high %yields were observed at 130, 140, and 130 °C, respectively. The DSC data were effectively applied for the estimation of the optimal reaction temperatures to attain high %yields for the synthesis of benzhydrols. The final benzhydrol derivatives 2a-c were structurally elucidated by FT-IR, ¹H NMR, and LC-MS and evaluated for antituberculosis activities by agar-dilution method. It was found that 4-hydroxy-α-(4ʹ-fluorophenyl) benzyl alcohol 2a possessed the highest activity in the series with the minimum inhibitory concentration (MIC) of 40 µg/mL.

Abstract: High Performance Fiber Reinforced Concrete (HPFRC) became very popular material for its high mechanical strength, elastic modulus and corrosion resistance. However, also its high-temperature resistance is of a particular importance because of the fire safety. Therefore, the effect of high-temperature exposure on UHPC reinforced by combination of steel and PVA fibers was studied in the paper. PVA fibers were used to moderate concrete damage induced by water vapor evaporation from dense UHPC matrix. The UHPFRC samples were exposed to the temperatures of 200 °C, 400 °C, 600 °C, 800 °C, and 1 000 °C respectively. Concrete structural changes induced by high temperature action were described by the measurement of basic physical and mechanical properties. The realized experiments provide information on the changes of concrete porosity and loss of mechanical resistivity.

Abstract: A Phase Change Material (PCM) based on paraffinic wax encapsulated in polymer shell is used for improvement of the heat storage capacity of commercially produced dry plaster, originally developed for both exterior and interior hand application. The composition of PCM modified plasters is designed with respect to the workability of fresh mixtures. Characterization of applied PCM is done using the measurement of particle size distribution, powder density, and matrix density. For the newly developed composite plasters, basic physical properties, mechanical properties, and thermal properties are accessed, whereas a specific attention is paid to the Difference Scanning Calorimetry (DSC) analysis. Using DSC measurement, temperatures of phase change transitions and phase changes enthalpies are identified. The obtained results show that the temperature induced phase change can be used for the release and storage of thermal energy in buildings, which can be beneficially utilized for saving the energy spent for the achievement of the indoor thermal comfort.

Abstract: The novel polyamide-imide-epoxy resin was prepared by modification of epoxy resin with polyamide-imide. The DSC curves of the polyamide-imide-epoxy resin were obtained with different heating rates. Moreover, the curing kinetics were also studied by using Kissinger equation, Ozawa and Crane formula, the activation energy of 55.24kJ/mol was acquired, reaction order was 0.9, the frequency factor A and the reaction rate constant Kp at the peak temperature of the reaction was also obtained.

Abstract: The mixture ratio between host crystal and curing agent of PU resin was calculated adopting the particle reaction principle based on the same equivalent weight, the results show that the mixture ratio between host crystal and curing agent of PU resin is 100:20～26; then through the analysis of DSC cures, viscosity-temperature cures, viscosity-time cures and the gelatin time under 25°C, the best mixture ratio of 100:20 was confirmed whose curing process and viscosity can well meet the requirements of the pipeline lining rehabilitation technology; in order to test and verify its operational performance, the adhesive strength between the resin and the pipeline wall was simulated and tested, the results show that the adhesive strength of the resin whose mixture ratio is 100:20 is high, that can meet the requirements of the pipeline lining rehabilitation technology.

Abstract: The reaction process and kinetics of Al-TiO2-C-Ti-Fe system were investigated by differential scanning calorimetry (DSC) analysis, X-ray diffraction (XRD) analysis and scanning electron microscope (SEM). In order to obtain the information of reaction process for complicated system, the reaction characteristics of Al-TiO2, Al-TiO2-C and Al-TiO2-C-Ti systems are explored firstly. The results show that the reaction process varies with temperature in Al-TiO2-C-Ti-Fe system. At the lower temperature, the dominating reaction in Al-TiO2-C-Ti-Fe system is that between Al and Ti, Al and Fe, and so TiAlx, FeAlx, and Ti2Fe intermetallic compounds form. With the temperature increasing, the intermetallic compounds are decomposed. Then the decomposed Ti and Al react with C and TiO2 respectively and the stable TiC, Al2O3 and Fe three phases form in the final product.