Dehydration Kinetics and Mechanism of Polyvinyl Alcohol Nanocomposite Hydrogels Containing Hydrophilic Na-Montmorillonite Nanoclay

In this work, polyvinyl alcohol nanocomposite hydrogels containing various loading levels of hydrophilic natural Na-montmorillonite nanoclay, i.e. 0-15 w-t% (based on the dried mass) were prepared via the freezing--thawing cyclic method. The effect of Na-montmorillonite on the gelation process and dehydration kinetic of prepared nanocomposite hydrogels was investigated.The results showed that the gel fraction values of nanocomposite hydrogels were increased by increasing the amount of nanoclay incorporated into them. On the other hand, dehydration results indicated that the dehydration rates of nanocomposite hydrogels had inverse dependency to the nanoclay loading level and direct dependency to the dehydration temperature. Finally, it was concluded that the dehydration mechanism of all prepared hydrogels at 20 C was non Fickian mechanism, while at 37 and 55 C theybehave according the Fickian mechanism.

کلیدواژه ها:

Nanocomposite hydrogel ، dehydration mechanism ، Polyvinyl alcohol ، Na-Montmorillonite