Swelling of liquids

Guadagno, T. and S.G. Kazarian, High-pressure C02-expanded solvents Simultaneous measurement of C02 sorption and swelling of liquid polymers with in-situ near-IR spectroscopy. Journal of Physical Chemistry B, 2004. 108(37) p. 13995-13999. 

Little has been published on the effect of Reynolds number on extrudate swell of liquids from fully three-dimensional dies. However, its effect on two-dimensional extrudate swell of a Newtonian fluid has been well characterized [1-4]. The influence of Reynolds number on the final die swell ratio for both planar jets (i.e., the thickness of the extrudate divided by the width of the channel) and axisymmetric jets (i.e., the diameter of the jet divided by that of the tube) are summarized in Fig. 1. In both cases, swell is greater than 1 for low Reynolds numbers but decreases to values less than 1 at high Reynolds numbers. As Reynolds number approaches infinity, the die swell ratios for the axisymmetric and planar jets approach the asymptotic values of /3/2 and 5/6, respectively [5,6]. 

Table 11. Swelling of Cross-linked Polyvinylpyrrolidone in Various Liquids at 20°C...

The traditional methods for measuring the swelling degree [100] are, as a rule, limited due to the difficulties in quantitative separation of the swollen gel from the outer solution because of extremely low strength of the former. These difficulties can be avoided by measuring the dimensions of a regular shape sample directly in an excess of liquid [19, 101,102], The other example is the modified volumetric method recently developed by us especially for SAH [103],... 

AB diblock copolymers in the presence of a selective surface can form an adsorbed layer, which is a planar form of aggregation or self-assembly. This is very useful in the manipulation of the surface properties of solid surfaces, especially those that are employed in liquid media. Several situations have been studied both theoretically and experimentally, among them the case of a selective surface but a nonselective solvent [75] which results in swelling of both the anchor and the buoy layers. However, we concentrate on the situation most closely related to the micelle conditions just discussed, namely, adsorption from a selective solvent. Our theoretical discussion is adapted and abbreviated from that of Marques et al. [76], who considered many features not discussed here. They began their analysis from the grand canonical free energy of a block copolymer layer in equilibrium with a reservoir containing soluble block copolymer at chemical potential peK. They also considered the possible effects of micellization in solution on the adsorption process [61]. We assume in this presentation that the anchor layer is in a solvent-free, melt state above Tg. The anchor layer is assumed to be thin and smooth, with a sharp interface between it and the solvent swollen buoy layer. 

The observed distribution can be readily explained upon assuming that the only part of polymer framework accessible to the metal precursor was the layer of swollen polymer beneath the pore surface. UCP 118 was meta-lated with a solution of [Pd(AcO)2] in THF/water (2/1) and palladium(II) was subsequently reduced with a solution of NaBH4 in ethanol. In the chemisorption experiment, saturation of the metal surface was achieved at a CO/Pd molar ratio as low as 0.02. For sake of comparison, a Pd/Si02 material (1.2% w/w) was exposed to CO under the same conditions and saturation was achieved at a CO/Pd molar ratio around 0.5. These observations clearly demonstrate that whereas palladium(II) is accessible to the reactant under solid-liquid conditions, when a swollen polymer layer forms beneath the pore surface, this is not true for palladium metal under gas-solid conditions, when swelling of the pore walls does not occur. In spite of this, it was reported that the treatment of dry resins containing immobilized metal precursors [92,85] with dihydrogen gas is an effective way to produce pol-5mer-supported metal nanoclusters. This could be the consequence of the small size of H2 molecules, which... 

Table 7.89 lists the main characteristics of MDHPLC (see also Table 7.86). In MDHPLC the mobile-phase polarity can be adjusted in order to obtain adequate resolution, and a wide range of selectivity differences can be employed when using the various available separation modes [906]. Some LC modes have incompatible mobile phases, e.g. normal-phase and ion-exchange separations. Potential problems arise with liquid-phase immiscibility precipitation of buffer salts and incompatibilities between the mobile phase from one column and the stationary phase of another (e.g. swelling of some polymeric stationary-phase supports by changes in solvents or deactivation of silica by small amounts of water).

Polymer gels and ionomers. Another class of polymer electrolytes are those in which the ion transport is conditioned by the presence of a low-molecular-weight solvent in the polymer. The most simple case is the so-called gel polymer electrolyte, in which the intrinsically insulating polymer (agar, poly(vinylchloride), poly(vinylidene fluoride), etc.) is swollen with an aqueous or aprotic liquid electrolyte solution. The polymer host acts here only as a passive support of the liquid electrolyte solution, i.e. ions are transported essentially in a liquid medium. Swelling of the polymer by the solvent is described by the volume fraction of the pure polymer in the gel (Fp). The diffusion coefficient of ions in the gel (Dp) is related to that in the pure solvent (D0) according to the equation ... 

L Westman, T Lindstrom. Swelling and mechanical properties of cellulose hydrogels. IV. Kinetics of swelling in liquid water. J Appl Polym Sci 26 2561-2572, 1981. 

Increase in dimensions of an elastomer due to the absorption of any organic liquid with which it may come in contact or in which it may be immersed. Measurement of the swelling of vulcanised rubber in solvents can be used to determine state of cure and to assess the suitability of elastomers for such uses as chemical plant lining or oil seals. 

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