Structural Parameters and Swelling Behaviour of pH Sensitive Poly (Vinyl alcohol)/ Poly (Ethylene oxide) and Poly (vinyl alcohol)/Xanthan Gum Hydrogels.

Hydrogels based on Poly(vinyl alcohol)(PVA), poly(ethylene oxide)(PEO) and Xanthan Gum(XG) cross linked with 25% (w/v) aqueous solution of Glutraldehyde (GA) were prepared. The effect of initial PVA/ PEO, PVA/XG weight ratio and the effect of amount of crosslinker (GA) on the dynamic and equilibrium swelling behaviour of the hydrogels was investigated. Hydrogels were characterized by percentage swelling, the polymer volume fraction in the swollen state, effective molecular weight of the polymer chain between two neighbouring crosslinks, mesh size and compressive strength. It was observed that the swelling capacity of the hydrogels decreases with increasing amount of crosslinker. The results show a significant influence of PEO and XG concentrations on the swelling behaviour of the PVA/PEO and PVA/XG hydrogels respectively. Hydrogels with higher PEO content had a higher percentage swelling mainly because of its hydrophilic nature and the percentage swelling was higher at pH 3.0 than at pH 7.4. On the other hand, addition of XG to PVA results in decrease in the swelling capacity of PVA/XG hydrogels. XG was found to add strength to the PVA/XG hydrogels. [ABSTRACT FROM AUTHOR]