Mineral kaolinite clay for preparation of nanocomposite hydrogels

Abstract

AbstractIn this work, nanocomposite hydrogels on the basis of polyvinyl alcohol and mineral kaolinite clay were prepared via freezing–thawing cyclic method without using any chemical crosslinkers as well as any intercalants for modification of kaolinite. The nanocomposite hydrogels were characterized by XRD, TEM, SEM, and FTIR methods. The effect of kaolinite content on the gel fraction values of nanocomposite hydrogels was investigated. Thermal and mechanical properties of prepared nanocomposite hydrogels were also studied using the DSC, DMTA, and hardness tests. Finally, the swelling and dehydration kinetics of nanocomposite hydrogels were studied at different temperatures. The morphology of prepared nanocomposite hydrogels was determined as intercalated morphology on the basis of XRD and TEM techniques. The role of kaolinite in the creation of supramolecular crosslinked network of polyvinyl alcohol was exhibited by FTIR and gel fraction tests. The thermal and mechanical experiments showed the reinforcing effect of kaolinite in the polyvinyl alcohol matrix. Swelling and dehydration tests showed that an increase of kaolinite content causes a decrease in the swelling ratio as well as in the dehydration rate of nanocomposite hydrogels. On the other hand, direct dependences of the swelling ratio and dehydration rate to the temperature were observed for all nanocomposite hydrogels. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012