Tomoyasu Ito

Hydrogen-Chemisorption Centers on Magnesium Oxide Formed by Pre-irradiation with Ultra-violet Light

~ ions in different tetragonal crystal fields in the surface region. Each type of the active center decayed thermally obeying second-order kinetics but with a different rate constant. Simple models for formation and decay of the active sites were proposed, and by the analysis of the H2-adsorption data, the activation energy and the rate constant for decay and the maximum number of the active site were estimated for each type. It was suggested that the H,-adsorption on these active centers resulted in the formation of Vs (2 OH) and Fs+type centers.

Analysis of the permeation of CO2 through glassy polymers

Abstract Dual-mode sorption and mobility parameters for the transport of CO 2 in glassy poly (ethylene terephthalate) were determined from the pressure dependence of the apparent diffusion coefficients, D a , below 1 atm at various temperatures. Experimental values of these diffusion coefficients were obtained from permeation time-lag measurements. Values of D a calculated by means of the above parameters are in excellent agreement with the experimental data. Moreover, the permeation time-lag curves calculated by the finite-difference technique in conjunction with the dualmode sorption parameters are consistent with the experimental time-lag curves. These results appear to support the validity of the dual-mode sorption model of gas transport in glassy polymers. However, equally good agreement between the calculated and experimental curves was obtained by using the apparent solubility and diffusion coefficient without the dual-mode sorption parameters. Similar results were obtained with poly(vinyl acetate)/CO 2 system at temperatures both above and below the glass transition temperature.

The effect of intra and inter potential for isotropic to nematic phase transition: a pressure-volume-temperature measurement study

Abstract A pressure-volume-temperature relation of 4-fluorophenyl trans-4-heptylcyclohexanecarboxylate (7CCF) was studied. The volume of the phase transition point decreased with increasing temperature. The -d ln Tc/d ln Vc value obtained was 2.98. This value, which includes information on the inverse power exponent of the potential function, was lower than those from 7CB or 7PCH, showing that the molecular softness effect of 7CCF arises from an intra-potential at phase transition larger than that of 7CB or 7PCH.

ISOTOPE EXCHANGE BY TRIBOCHEMICAL REACTION

Isotope exchange reaction H2 + D2 = 2HD occurs at room temperature tribochemically by vibration of SiC. This reaction, which is distinct from thermal reaction, has an induction period at initial stage and the rate of the reaction increases with increasing vibrating time.