Swelling of hydrophilic polymers. IV

Abstract

SYNOPSISThe swelling of five types of spherical crosslinked dextrans (Sephadex) that are either nonionic (G) or ionic [carboxymethyl (CM), sulphopropyl (SP), diethylaminoethyl (DEAE), and diethyl-(2-hydroxypropyl)aminoethyl (QAE)] in the same skeleton has been studied in water at different dissolved oxygen concentrations by microscopic observation and by dilatometry. The maximum specific volume, Vm,,/Vo obtained by microscopic observation increased with the lowered dissolved oxygen concentration for each Sephadex. The change of the maximum specific volume was closely related to the changes of the dissolved oxygen concentrations. The maximum changes of the total volume took the larger negative values at the lower dissolved oxygen concentration. The effect of the difference in the dissolved oxygen on the change of the total volume with swelling was closely related to the viscosity B coefficient of the Jones-Dole equation. From these results, we conclude that the structure of water on the inside of the gel differs from that on the outside of the gel.

Absorption and desorption of liquid water by a superabsorbent polyelectrolyte: Role of polymer on the capacity for absorption of a ground

“…The Na ϩ ions come to fit between the polymeric chains and hidingplace between the loads carried by the macromolecule what minimizes the electrostatic repulsion 11 thus involving a reduction in the maximum rate of absorption. 12,13 The presence of the mono-valent ions K ϩ and NH 4 ϩ induces (by effect shielding) a reduction in the capacity for absorption of polymer, as in the case of NaCl; only differs the of electrostatic forces ensuring the interaction ions-site charged. These forces of attraction depend not only on the load of the ion but also on its ray and its polarizing capacity.…”

Application of deaerated water in swelling of cellulose and amylose and cotton desizing with enzyme

“…The total volume change measured by dilatometry shows the degree of the hydration of water and polymer. 3,4 In deaerated water, the hydration is thought to be 142 Ϯ 6% for cellulose and 229 Ϯ 2% for amylose to the hydration in air-present water. The rate constants, k, at low c DO is smaller than those in high c DO water for both cellulose and amylose.…”

“…⌬v values correspond to the quantities of interaction between water and the polymer. 4 The temperature was maintained at 25.000 Ϯ 0.001°C during the measurement.…”

“…6 -9 Some other researchers have studied the application of deaerated water in food processing. 10 -12 In our previous article, 4 the effect of dissolved air in water on the swelling of hydrophilic polymers was investigated. Both the hydrobondings between water and polymers and the dissociation of ionic dissociable groups of polymers were increased in water with a low-dissolved oxygen concentration.…”

“…[1][2][3][4][5] The degree of interaction between the polymer and water measured by dilatometry was different in air-present water from in deaerated water that was obtained by cooling in a sealed container after boiling. 3,4 Air-present water in equilibrium with air contains about 16 mg L Ϫ1 of nitrogen, 7-8 mg L Ϫ1 of oxygen, and some inert gases at room temperature. These days, the deaerated water, which is the water after these dissolved gases are removed, can easily be obtained with membrane technology.…”