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A dramatic improvement of the toughness of polydicyclopentadiene (PDCPD) composite containing low amounts of vinyl-functionalized SiO2 was achieved, and the toughening mechanism was investigated. Considering the nonpolarity of the DCPD monomer and the probability of covalent bonding between SiO2 and DCPD, vinyl-functionalized SiO2 (V-SiO2) with a high content of vinyl groups was prepared by a facile, reproducible, one-step, remodeled synthetic sol-gel process. The V-SiO2 was characterized with respect to the content of vinyl groups, particle size, and morphology by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), dynamic light scattering (DLS), and field-emission scanning electron microscopy (FE-SEM). PDCPD/V-SiO2 composites were prepared by in situ polymerization. The mechanical properties of the PDCPD/V-SiO2 composites were investigated by universal testing machine (UTM) and dynamic mechanical analysis (DMA). A slight decrease in the yield strength was observed with increasing loading of V-SiO2, whereas the elongation at break increased substantially from 9.0% to 143.4% and the tensile toughness increased by a factor of 14 compared to that of neat PDCPD when just 0.2 wt % V-SiO2 had been added. The dramatic toughness enhancement is attributed to the formation of microvoids and microcracks during the process of stretching, which can absorb a great deal of energy. [ABSTRACT FROM AUTHOR]

Two micromesoporous composites of MCM-41/13X are synthesized through a two-step crystallization process and a one-step crystallization process, respectively. The results of X-ray diffraction, nitrogen adsorption-desorption isotherms, Fourier transform infrared spectroscopy, and transmission electron microscopy results show that the as-prepared samples possessed both micropores and mesopores. The materials take advantage of not only the large adsorption capacity and thermal stability of the microporous material, but also the rapid diffusion and mass transfer of mesoporous materials, which lead to improve CO2 adsorption capacities compared to the pure microporous or mesoporous materials. [ABSTRACT FROM AUTHOR]

It is remarkable that Brønsted acidic ionic liquids(BAILs)have several unique advantages in the acid-catalysis reaction, whichavoids the technical issues raised from mineral acids. The kineticsfor the ketalization of cyclohexanone with glycol using BAILs as catalystswas therefore studied for the first time. The effects of various parameterssuch as kind of BAILs, temperature, catalyst loading, and molar ratioof the reactants on the conversion of cyclohexanone were examinedin detail, and a pseudohomogeneous (PH) kinetic model was used successfullyto correlate the experimental data in the temperature range from 313.15to 343.15 K. The kinetic parameters such as reaction rate constant,activation energy, and chemical equilibrium constant then were proposedand utilized to interpret the catalytic activities of the BAILs catalysts.It was also validated from the comparison of catalytic performanceamong the BAILs, H2SO4, and solid resin thatthe BAILs were considered to be environmentally friendly and highefficient catalysts, and were suggested to replace mineral and solidacids in the synthesis of ketal. [ABSTRACT FROM AUTHOR]

Crystallization and coarsening kinetics of nonisothermalprecipitationprocess of rutile in modified Ti-bearing blast furnace slag were discussed.The modified slag was analyzed by X-ray diffraction (XRD) and scanningelectron microscope (SEM) and EDX. The experimental results showedthat the cooling rate has an important effect on precipitation ofthe rutile phase. Low cooling rate is in favor of the increase inthe volume fraction of rutile phase in Ti-bearing blast furnace slagand the growth of rutile phase. The volume fraction of rutile phasewas approximately described by JMAK equation. The experiential expressionof average crystal radius for rutile phase was also obtained. [ABSTRACT FROM AUTHOR]

The motion of a single bubble rising unsteadily and steadily in a quiescent non-Newtonian liquid was investigated experimentally. By using a charged coupled device camera to follow the rising bubble, the sequences of the recorded frames were digitized and analyzed using image analysis software, and the measurements of the acceleration and steady motion of bubbles were obtained. Using the experimental data, we proposed an empirical correlation to predict the total drag coefficient calculated from the accelerating motion to the steady motion with the added mass force and history force included. This correlation is an extension of our previous work with non-Newtonian fluids. This new correlation represents very well the experimental data of the total drag force in a wide range covering both unsteady accelerating motion and steady motion in non-Newtonian fluids. [ABSTRACT FROM AUTHOR]