Sorption and swelling

Mitrevej, A., and Hollenbeck, R.G., Photomicrographic analysis of water vapor sorption and swelling of selected super disintegrants, P/zarra. Tech., 6 48-50 (1982). 

In order to account for the well known sorption and swelling properties of polymer ion exchangers, Helfferich s model [427] is frequently used for liquid phase reactions. According to this, the pore liquid of the resin, where the reaction occurs, is treated as a homogeneous system and the reactant is assumed to be distributed according to a distribution coefficient... 

Sorption and swelling are accompanied by the evolution of heat (Katz [33]). Water sorption causes the evolution of some 3.5-6.0 kcal/mole. The heat of swelling in the presence of sodium hydroxide depends on its concentration. When a 5-18% sodium hydroxide solution is used, the heat of swelling amounts to 13-30 cal/g of cellulose. 

An Experimental Method to Determine the Sorption and Swelling Behavior of Solids at High Pressures... 

The sorption of alkali metal ions by periodate lignin increased rapidly with increasing alkali concentration and leveled off to an approximate value of 1.5 meq g lignin at about 1% alkali [285]. Interestingly, both alkali sorption and swelling of the lignin were found to decrease at alkali concentrations above the 9% level. 

H. Rave, R. Staudt, J.U. Keller Measurement of sorption and swelling behaviour of polymer/C02 systems by a combined oscillometric-gravimetric method. Proeedings. of P3AC2, Brisbane, May 14-18, 2000, World Scientific, Singapore 2000. 

In this chapter, we present results of the testing of a broad spectrum of polymers in carbon dioxide over a range of temperatures and pressures and evaluation of the effect of the high pressure carbon dioxide on the chemical/physical properties of materials tested. The testing was performed in a static manner with four controlled variables, namely temperature, pressure, treatment time and decompression time. The evaluation of the interaction of high pressure carbon dioxide with polymers included sorption and swelling behavior, solubility issue, plasticization and crystallization, and mechanical properties. The results of these evaluations are discussed in three sections Sorption, Swelling and Dissolution of Carbon Dioxide in Polymers at Elevated Pressure, Thermal Properties, and Mechanical Properties. ... 

Although there is no bulk liquid with which adsorbed cations can be exchanged in the experiments made in atmospheres of controlled relative humidity, successive experiments can be made with different adsorbed cation populations, and it is found that the succession of dehydration steps varies with size and hydration energy of the cation (Posner and Quirk, 1964). There is also a dependence upon the type and extent of substitution in the aluminosilicate framework White (1958), for example, observed that two montmorillonites with the same cation-exchange capacity, loaded with the same cation, may have different water sorption and swelling properties. 

ZHA ZMng, Y., Gangwani, K.K., and Lemert, R.M., Sorption and swelling of block copolymers in the presence of supercritical carbon dioxide, J. Supercrit Fluids, 11, 115, 1997. 

BON Bonavoglia, B., Storti, G., Morbidelli, M., Rajendran, A., and Mazotti, M., Sorption and swelling of semicrystalline polymers in supercritical CO2, J. Polym. Sci. Part B Polym. Phys., 44, 1531, 2006. 

P1N Pini, R., Storti, G., Mazzotti, M., Tai, H., Shakesheff, K.M., and Howdle, S.M., Sorption and swelling of poly(DL-lactic add) and poly(lactic-co-glycolic acid) in supercritical CO2, Macromol. Symp., 259,197,2007. 

Variations in the thomal properties (v and vi from above) and the mechanical properties (vii from above) for polymaic materials are discussed sq arately in Sec. 3. This section details our results on sorption and swelling of polymers by carbon dioxide and the dissolution characteristics of various polymeric materials under a variety of conditions. A comparison will be shown for wdght change data of twenty different polymers that have been treated in both sub- and supercritical carbon dioxide at seven different conditions. These results are discussed in general to isolate important factors which affect the weight change (and possibly dimensions) of polymers. 

W12 Wissinger, R.G. and Paulaitis, M.E., Molecular thermodynamic model for sorption and swelling in glassy polymer-C02 systems at elevated pressnres, Ind. Eng. Chem. Res., 29, 842, 1991. 

FL1 Fhchy, N.M.B., Kazarian, S.G., Lawrence, C.J., and Briscoe, B.J., An ATR-IR study of poly(dimethylsiloxane) under high-piessuie caibon dioxide simultaneous measuiement of sorption and swelling, 7. Phys. Chem. B, 106, 754, 2002. 

For this and other reasons, concerning the mechanism of the processes considered, it is not practical to separate sorption and swelling, since a definite limit can not be traced between the two. Neither can we separate sorption of condensable vapours and swelling in the corresponding liquid substance, since the latter is, for obvious reasons, identical with sorption at the saturation pressure of the vapour. 

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