Swelling and flow properties of tubular poly(vinyl alcohol) gels

Swelling and flow properties of tubular poly(vinyl alcohol) (PVA) hydrogels prepared with the cooling method were investigated using an inflation test ing method. When the tubular hydrogel in liquid paraffin was inflated by us ing liquid paraffin as a pressure transmitting medium, namely in the case t hat the liquids inside and outside the gel are both liquid paraffin (P/P co mbination), the gel showed a slight volume change determined by Poisson's r atio of the gel. When the gel in water was inflated by liquid paraffin (P/W combination), the gel swelled to large extent compared with the case of P/ P. The hydrogel in W/W combination, namely in the situation that the gel wa s immersed in water and also inflated by water, showed a very large volume change if the comparison was done at the same pressure. The origin of the v olume change in PIP, P/W and W/W combinations is discussed. The volume chan ge in P/P was governed by the Poisson ratio as a material constant (mu(0)) of the PVA gels, and the gels swelled by the change in the application of p ressure (or deformation) in P/W. The volume change in W/W was closely relat ed to the how of solvent in the gel.