Volume swelling ratio

Now the post-gelation period of the copolymerization of divinyl/vinyl monomers in the presence of a good solvent as a diluent will be considered. Let Qv(x) be the equilibrium volume swelling ratio of the gel formed at conversion x, and Q°(x) its degree of dilution in the reaction system, i.e.,... 

Swelling profile determinations of the hydrogel films are provided elsewhere [35]. The results were given as the volume swelling ratio plotted... 

P2,13 permeability coefficient of solute in water swollen polymer Q equilibrium volume swelling ratio... 

Volume swelling measurements have produced erratic results even under the most carefully controlled conditions. One important contribution in this regard is the work of Bills and Salcedo (8). These investigations showed that the binder-filler bond could be completely released with certain solvent systems and that the volume swelling ratio is independent of the filler content when complete release is achieved. Some thermodynamic problems exist, however, when such techniques are used to measure crosslink density quantitatively. First, equilibrium swelling is difficult to achieve since the fragile swollen gel tends to deteriorate with time even under the best conditions. Second, the solubility of the filler (ammonium perchlorate) and other additives tends to alter the solution thermodynamics of the system in an uncontrollable manner. Nonreproducible polymer-solvent interaction results, and replicate value of crosslink density are not obtained. 

The volume swelling ratios (Vr) are inversely proportional to the equilibrium volume fraction of the rubber in the corresponding swollen systems (filled and gum, represented by subscripts f and 0, respectively), such that ... 

Weight swelling ratio = Volume swelling ratio/c(... 

Theoretical curves for Model I or Model II were obtained by solving equation (3) or equations (4) and (5), respectively. An iteration method was used with the aid of a DEC-20 computer. The calculated volume swelling ratio (v/v ) was then plotted against the interfacial energy term (rQRT/2V Y /. ... 

Volume swelling ratio (swollen gel volume / dry gel volume)... 

Fig. 2 The modulus of elasticity Go, the effective crosslink density Vo (a) and the volume swelling ratio 2v of PAAc hydrogels in water (b) as function of the polymer network concentration ip2, 1.2 mol % MBAAm. The inset to Fig. 2a shows a double logarithmic Go vs. 9 plot. Reprinted from Yazici and Okay (2005) with kind permission from Elsevier...

Fig. 3 Equilibrium volume swelling ratio of ionic PAAm hydrogels shown as function of the NaCl concentration in the external solution 1.2 mol % MBAAm. AMPS Namole fraction x,-in the comonomer mixtures is indicated. Reprinted from Durmaz and Okay (2000) with kind permission from Elsevier...

The volume swelling ratio for smaller gel cylinders can be expressed as ratio of gel volume in equilibrium state (F) to volume at preparation (Vq) measured as the ratio of the respective diameter of the cylinder in equilibrium state (d) to the diameter at preparation (do) ... 

Fig. 5 Volume swelling ratio of graft copolymer gels (a) in response to temperature at constant pH (pH=3) (open square CPNI open circle CPNIPYl open triangle CPNIPY2 open down triangle CPNIPY3) (b) in response to pH at constant temperature (T = 22°C) (open square CPNI open circle CPNIPYl open triangle CPNIPY2 open down triangle CPNIPY3)...

Equilibrium volume swelling ratio (with respect to diy state) Equilibrium weight swelling ratio (with respect to dry state)... 

Volume swelling ratio with respect to the after preparation state of gels Total volume of open pores... 

Fig. 7 (a) The elastic modulus G, (b) the equilibrium weight q and volume swelling ratios q, and (c) the swollen state porosity and the dry state porosity P of PAAm gels shown as functions of the cryogelation temperature Tpr p- (d) SEM images of PAAm networks formed at the various... 

Fig. 11 The equilibrium volume swelling ratio Frei left) and the elastic modulus G of equilibrium swollen PAMPS hydrogels right) shown as a function of Tp p. Filled and open symbols represent data obtained from I- and N-gels, respectively. X = 1/6. TTie dotted lines represent the transition temperature. (From [23] with permission of Taylor Francis Group, LLC)...

From this equation, the equilibrium volume swelling ratio, Q, i.e. the reciprocal of ds.s, can be expressed in terms of all the crosslinked structure and ionic solution... 

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