Effects of Nanoclay on Cellular Morphology and Water Absorption Capacity of Poly(vinyl alcohol) Foam

The present work was aimed to examine the effects of incorporation of each of two different types of nanoclay, i.e. Cloisite Na+ and Cloisite 30B, into PVA foam on cellular morphology and water absorption capacity. Foam samples containing 0.0-10.0 wt% of each of the two types of nanoclay alone were prepared using mechanical foaming. Accordingly, PVA/organoclay/water suspensions were prepared first. Then other agents, i.e. catalyst, surfactant and crosslinking agent were added, respectively, to each of the prepared suspensions rendering primary froths, which were converted to final foam samples at room temperature during a period of 24 h. State of clay dispersion in the polymer matrix and cellular morphology of the prepared foam samples were examined using X-Ray Diffraction (XRD) technique and Field Emission Scanning Electron Microscopy (FESEM), respectively. Also, dry foam density and water absorption of the foam samples were measured gravimetrically. XRD patterns revealed the existence of intercalated and exfoliated structures in the PVA/Cloisite 30B and the PVA/Cloisite Na+ foam samples, respectively. FESEM images demonstrated open-cell morphology for all the samples but the extent of cell wall rupture was more significant in the case of PVA/nanoclay foam samples. In addition, water absorption capacity of the PVA foam was shown to be decreased by the incorporation of either of the two types of nanoclay, which was explained in terms of the lower total pore volume in the PVA/nanoclay foam samples than in the neat PVA foam sample. Finally, the obtained results were explained in terms of the effects of the nanoparticles on the elevation of the rate of the drainage in the crosslinking PVA solution before the stabilization of the cellular structure.