Shuichi Shimomura

Electron spin resonance studies on silver atoms in imogolite fibers

The formation and stabilization of reduced silver species in imogolite have been studied by electron spin resonance (ESR) spectroscopy. Ag-loaded imogolite samples after degassing and dehydration were γ-irradiated at 77 K and monitored by ESR as the temperature increased. Some samples were exposed to methanol vapour after dehydration. It was found that imogolite shows exceptional ability to stabilize silver atoms. In dehydrated Ag-imogolite silver atoms generated at low temperature remain stable at room temperature. Silver atoms are also formed in imogolite samples exposed to methanol. However, in contrast to silver agglomeration in molecular sieves and smectites exposed to methanol there is no indication of the formation of cationic silver clusters in Ag-imogolite. It is postulated that there are special trapping sites in imogolite structure which effectively stabilize silver atoms.

Porous clay-fiber composite: a potential substitute for foamed styrol

Using sorely smectite clay and fibers of used paper, a porous composite was made. Lyophylization of the composite sol is the principle of its processing. Clay/fiber ratio and porosity are variable. The composite has elasticity that confirmed for a clay-fiber composite porous material of 90% porosity. Its compressive strength is about 550 g/cm2. Since the increase of its compression strength by use of humic acid as additives has previously be known, the material is a potential substitute, at least in some part, of polystyrene foam, a petroleum product.

Young’s Modulus of Fullerene C60–C70 Alloy Crystalline Nanowhiskers

Crystalline nanowhiskers (NWs) composed of fullerene C60 and C70 molecules, i.e., alloy NWs, were synthesized by a liquid-liquid interfacial precipitation method. The nominal composition of C70 ranged from 0 to 40 mass%. The bending tests of the alloy NWs were performed inside a high-resolution transmission electron microscope, and the deformation behavior was observed in situ. The bending force acting on the NWs were measured simultaneously by an optical deflection method, and the Youngs modulus was estimated from the resulting force-flexure curves. The average Youngs modulus was found to increase to approximately 30 GPa as the C70 composition was increased to the solubility limit. In contrast, the Youngs modulus decreased with increasing NW diameter caused by the addition of C70.