Hiromi Gocho

Effect of polymer chain end on sorption isotherm of water by chitosan

Abstract In this study, the sorption isotherms of water vapor by chitosans with various molecular weights were measured. The BET adsorption theory was modified for the system that has several different kinds of energy levels in the water adsorption sites, i.e. a hydroxyl group, an amino group, the polymer chain end, etc. and applied it to the experimental results in order to examine the effect of the polymer chain end on the sorption isotherm of water–chitosan using the parameters which represented the total number of adsorption sites, V m , the interaction energy between water and the adsorption sites, K , and the number of adsorbed layers, n . V m and K increased as the molecular weight decreased, and n remained constant. It has been proved that the increase in V m and K were caused by the hydrophilic groups in the polymer chain end.

Effect of acetyl content on the sorption isotherm of water by cellulose acetate: comparison with the thermal analysis results

Abstract In this study, the sorption isotherms of water vapor by cellulose acetate for various acetyl contents were measured. The BET adsorption theory was modified for the system which has two different kinds of energy levels in the water adsorption sites, i.e. a hydroxyl group and an acetoxyl group, and applied it to the experimental results in order to examine the effect of acetyl content on the sorption isotherm of water using the parameters which represented the total number of adsorption sites, V m , the interaction energy between water and the adsorption sites, K , and the number of adsorbed layers, n . V m and K decreased with an increase in acetyl content and n remained constant. The apparent activation energies of the water desoption were also determined using differential thermal analysis. They are nearly constant with an increase in the acetyl content.