The effect of soil-based material on the controllability of indoor climate was investigated. The material produced by a hydrothermal reaction had higher moisture adsorbing/desorbing ability than wood and almost the same heat capacity as concrete. The utilization of soil-based material as an interior floor finishing one reduced variation in temperature and humidity inside the room as well as residential energy consumption. Furthermore, numerical simulation was applied to estimate thermal control property of the material in indoor space.
Synthesis of zeolite Y was studied by using a hydrothermal reaction system including cationic polymer, poly (diallyldimethylammonium chloride) and effects of the polymer on nucleation and crystallization were investigated under a variety of reaction conditions. Xray diffraction technique was used for identification and the determination of zeolite content in the reaction products. The changes of the crystal surface morphology, size and shape of crystals forming during the reaction were studied by using SEM. Detailed observations were also performed for both the reaction products composed of crystal and/or amorphous precursor involving polymer component and their calcined products obtained at 600°C for 24 h. Reaction mechanism was analyzed and apparent activation energies of nucleation and crystallization were determined. A characteristic phenomenon was found in the latter stage of reaction in the cationic polymer present system. The rate of crystallization suddenly drops to a constant rate and then the rate continues until the reaction reaches to completion. It was presumed for polymer effect on crystallization that the cationic polymer chain on the growing crystal surface controls the diffusion of active cluster comprising of anionic chemical species to growing sites of crystal.
The formation process of magnesium aluminate (MgAl2O4) due to the solid-state reaction of highly-dispersed and nanometer-sized aluminum and magnesium compounds has been examined by high-temperature X-ray diffractometry (HT-XRD), synchrotron radiation diffractometry (SRD) and X-ray photoelectron spectroscopy (XPS). The starting compounds were α-and γ-aluminum oxide (α-and γ-Al2O3; primary particle sizes, 105 and 31.6 nm, respectively) as aluminum sources, and magnesium oxide (MgO; 41.3 nm) and magnesium hydroxide (Mg (OH) 2; 61.1 nm) as magnesium sources. Through the combination of these compounds, four powder mixtures were prepared, namely, (i) α-Al203 and MgO, (ii) γ-Al2O3 and MgO, (iii) α-Al2O3 and Mg (OH) 2, and (iv) γ-Al2O3 and Mg (OH) 2. Phase change investigation during the heating of these mixtures indicated that the formation of MgAl2O4 due to the reaction of γ-Al2O3 with Mg (OH) 2 was faster when compared to the other combinations; almost single phase of MgAl2O4 could be obtained when this mixture was heated at 1200°C for 1 h. More detailed investigation on the formation process of MgAl2O4 was conducted using the precursor mixture of γ-Al2O3 and Mg (OH) 2 heat-treated at 800°C for 1 h. The data obtained from SRD and XPS suggested that small amounts of MgAl2O4 and ce-Al2O3, together with γ-Al2O3 and MgO, were present in this precursor. The formation of MgAl2O4 due to the reaction of γ-Al2O3 with Mg (OH) 2 was found to occur readily due to active mass transfer as a result of the very small primary particle and agglomerate sizes.