Solubility parameter disparity

The smaller the solubility parameter disparity of solvent and polymer, the better the compatibility of solvent and polymer, and the slower the precipitation of the polymer. Thus, the tendency for a change from a sponge to a finger... 

A swap of the blend component stained with deuterium results in the interrelated changes in surface %s and bulk % interaction parameter. The model presented above accounts for this relation, using the solubility parameter formalism introduced in Sect. 2.2.3. Large magnitudes of the swapping effect for bulk and, hence, surface interactions observed in 66/52 and 86/75 blend pairs lead to the observed disparity in surface phase behavior noticed within each pair (see Fig. 28). Extended critical point wetting region is concluded for d66/h52 and d86/h75 mixtures with (-%s) >0.014, while its very drastic reduction is concluded for the blends with swapped isotope labeled component, i.e., for h66/d52 and... 

The Effect of the Polymer-Solvent-Precipitant System on Membrane Structure and Properties. The effect of the polymer on membrane structure and properties is closely related to the solvent used in the casting solution and the precipitant. The solvent and the precipitant used in membrane preparation determine both the activity coefficient of the polymer in the solvent-precipitant mixture and the concentration of the polymer at the point of precipitation and solidification. The polymer-solvent-precipitant interaction can be approximately correlated in terms of the disparity of the solubility parameter of polymer and solvent. 

Since water (the precipitant) has a solubility parameter (23.4) higher than any of the solvents investigated, it would appear experimentally that the disparity between the solubility parameters of the solvent and the precipitant is a key factor in understanding these results. 

Koningsveld et al, have derived a spinodal expression for mixtures of random copolymers from Scott s free energy of mbcing [equation (9)]. According to it, the location of the miscibility gap is determined entirely by the difference in overall chemical composition between two copolymers and not by their individual compositions. They conclude that while chemical composition and disparity in molecular volumes of the two monomers are important factors, the data are too scanty at present to rule out the possibility of other influences. Casper and Morbitzer have studied polym and copolymer mixtures using a lattice-graph model with interactions estimated from solubility parameters. 

Physical and Chemical Properties. The physical and chemical properties of bromomethane are sufficiently well known to allow estimation of environmental fate. Although there is some disparity in reported values for the solubility in water and Henry s law constant for bromomethane (see Table 3-1), further studies to define these parameters more precisely do not appear essential, since volatilization from water is so rapid. 

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