Interaction of poly(vinyl alcohol) with poly(acrylic acid) and with sodium polyacrylate in aqueous solutions: a volumetric study at 25° C.

The infinite dilution partial molar volumes of poly(acrylic acid), at different degrees of neutralization with sodium hydroxide, have been experimentally determined in aqueous solutions. Analysis of the data indicates that, the observed trend can be interpreted in terms of the electrostriction of the water molecules involved in the hydration cospheres of the carboxylic groups. The presence of PVA does not significantly affect the undissociated acid, but causes a large decrease for the sodium salt. This aspect has been discussed in terms of direct interaction between the two polymers