Volume degree of swelling

Since the equilibrium volume degree of swelling Q equals l 2, this equation shows that the parameters which control swelling are the polymer-solvent interaction parameter % and the effective cross-link density pt. Figure 2 shows that Q falls as either % or p) increases, although the influence of the cross-link density becomes negligible in poor solvents. 

Here m, p and V denote weight, density and volume of the two components, i.e coal and swelling agent, which are designated by the subscripts c and s respectively then V g designates the volume of the swollen coal. An apparent volume degree of swelling, Qapp, can also be determined from equation (6). 

The film thickness of hydrogel layers from 5 wt % solutions was in the order of 1 jun in the swollen state. Thickness (d) and refractive index (q) were determined without further assumptions, because these films could be fitted using a single layer model [19], The refractive index (q) obtained from Fresnel calculation was converted to polymer fraction and volume degree of swelling (1/0P). 

Fig.3 Volume degree of swelling of the photo cross-linked PNIPAAm hydrogel layer with varying DMAAm content plotted as a function of temperature in PBS buffer ( - NIPAAm5, o - NI-PAAmlO, A - NTPAAm20. V - NIPAAm30, 0 - NIPAAm40)...

Fig. 5 Change in volume degree of swelling in PBS buffer at constant temperatures with varying DMAAm content ( - 15 °C, o -55 °C). Lines are drawn to guide the eyes...

The polymer volume fraction 92 is defined as ratio of polymer volume to the sum of the volumes of polymer and solvent. To describe the swollen state of a cross-linked polymer, we introduce the volume degree of swelling as ratio of the... 

The volume degree of swelling can be determined either by measuring the volume of swollen and dry sample (e.g., determination of sample height or thickness), or if the densities of the solvent and the dry polymer p2 are known by weighing the swollen (nil + 2) and dry (m2) sample (10). 

Fig. 1 Calculated and measured ( ) swelling curves for PNIPAAm of different molecular weight-of the net chains in g/mol. The Flory-Huggins interaction parameter % was calculated using (12). The dashed curve was calculated considering only a temperature-dependent x (X2 = 0)-The sharp decrease of the volume degree of swelling with temperature is only observed for concentration-dependent interactions. The sharpness of the curve is influenced by Me...

The volume degree of swelling of cross-hnked polymers is simply the inverse of the polymer volume fraction. For a cylindrical sample, can be obtained from the diameter of the swollen d and the dry cylinder as... 

Degree of swelling Mass degree of swelling Volume degree of swelling Gas eonstant (8.314 J K moP )... 

The volume degree of swelling, Q. i.e., the ratio of the actual volume of a sample in the swollen state divided by its volume in the dry state, is expressed as... 

Time decrease of relative turbidity and volume degree of swelling, in PHEMA gels swollen in butanol Qq and q are the initial and equilibrium degrees of swelling, respectively Tq initial and maximum... 

The volume degree of swelling and phase volume ratio calculated from the integral equations of the form of Eq.(6) agrees fairly well with experimental data when toluene and polystyrene are used as diluents. Thus for 67% toluene (% = 0,46) and 30% divinylbenzene, the calculated volume fraction of the network phase at full conversion was 0,55-0,60, which is in agreement with the experimentally observed value 0.53, The observed and calculated toluene regain as 2.25 and 2.70 ml/g, respectively. When the monomers are diluted with more than about 20% iso-octane (a poor solvent), the agreement between calculated and experimental values of phase volume ratio becomes poorer. In that case, the monomer-diluent mixture is so poor that phase separation takes place already before the gel point has been reached. 

Volume degree of swelling of ST-DVB copolymers related to the swelling of the copolymer prepared in the absence of diluent, 1- 20% DVB, diluent iso-octane,... 

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