Abstract
AbstractThe temperature dependence of the second virial coefficient, A2, in an aqueous solution of poly (vinyl alcohol) (PVA) has been studied by the light‐scattering method within the temperature range from 20 to 130°CC.The experiment was carried out under conditions which rule out the aggregation of macromolecules. The temperature dependence of A2 has the form of an extremum with an unpronounced minimum between 80–90°CC. In the temperature region studied here, A2 > 0, this condition is regarded as a proof of the stability of the system with respect to amorphous separation. Consequently, the supermolecular order which forms in the PVA‐water system over this range of temperatures (see Chem. Abst, (1967), 66: 11295u; (1971) 73, 56516x; (1971) 74, 23183d) has a crystalline nature.The literature noting an increase in the degree of sweiling with increasing temperature in the PVA‐water system in the interval 20–80°CC, which seems contradictory to a decrease in the solvent power (decrease in A2), may be explained by a decrease in the degree of crystallinity (degree of physical crosslinking) of the polymer.
Published Version
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