Kyonggi University

About: Kyonggi University is a education organization based out in Suwon, South Korea. It is known for research contribution in the topics: Catalysis & Dielectric. The organization has 1946 authors who have published 4404 publications receiving 64791 citations.

Gas permeation properties of organic-inorganic hybrid membranes prepared from hydroxyl-terminated polyether and 3-isocyanatopropyltriethoxysilane

Abstract: Organic-inorganic hybrid materials were prepared by reacting 3-isocyanatopropyltriethoxysilane (IPTS) with hydroxyl terminated poly(ethylene glycol) (PEG), poly(propylene glycol) (PPG) and poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) (PEPG), followed by hydrolysis and condensation with acid catalysis Composite membranes have been obtained by casting hybrid sol on the microporous polysulfone substrate The membranes were characterized by Fourier transform infrared (FT-IR), 13C NMR and 29Si NMR The permeability coefficients of N2, O2, CH4 and CO2 were measured by variable volume method The gas permeability coefficients increase with increasing molecular weight of the polyethers For the membranes containing PEG and PEPG, the higher values of CO2 permeability coefficients and CO2/N2 separation factors are due to the presence of ethylene oxide segments In case of PEPG membranes, molecular weight has more influence on CO2 permeability than the effect of facilitation by ethylene oxide The addition of TEOS into hybrid sol results in the decrease of all the gas permeability and does not affect the gas selectivity PEG2000 membrane display the most performance among the hybrid membranes investigated here The best values observed are CO2 permeability of 942 Barrer with selectivity of 383 for CO2/N2 and 156 for CO2/CH4

Low-temperature sintering and microwave dielectric properties of [Ca0.6(Li0.5Nd0.5)0.4]0.45Zn0.55TiO3 ceramics

Abstract: The effects of ZnO–H 3 BO 3 on the sinterability and microwave dielectric properties of [Ca 0.6 (Li 0.5 Nd 0.5 ) 0.4 ] 0.45 Zn 0.55 TiO 3 (CLNZT) ceramics were investigated. With the addition of ZnO–H 3 BO 3 from 1.0 to 4.0 wt.%, Qf value of CLNZT sintered at 900 °C were as good as those of pure CLNZT sintered at 1150 °C. This is due to the enhancement in density of CLNZT by liquid phase sintering by the addition of ZnO–H 3 BO 3 . Dielectric constant ( K ) was increased remarkably with ZnO–H 3 BO 3 content for the specimens sintered at temperatures lower than 950 °C. Typically, K of 42, Qf of 10 300(GHz), TCF of 19.5 ppm °C −1 were obtained for CLNZT with 2 wt.% 0.33ZnO–0.67H 3 BO 3 sintered at 875 °C for 4 h.