Properties of poly(vinyl alcohol)-Bentonite clay nanocomposite films in relation to polymer-clay interactions

摘要

This study describes an effective way for the preparation of well-dispersed, high-loaded PVA/bentonite nanocomposites with improved properties, based on nanoscale interactions. To this end, a series of Poly(vinyl alcohol)-bentonite clay nanocomposites have been prepared via solvent casting technique and their properties were thoroughly investigated by atomic force microscopy, transmission electron microscopy, X-Ray diffraction, oxygen and water permeability, water sorption along with mechanical and thermal studies. Microscopic and XRD techniques revealed highly organized regions. Clay content up to 10% led to nanocomposites with high degree of exfoliation. In addition samples with increased filler content (20%) demonstrated also, apart from the delaminated, well-organized intercalated regions. The nanocomposites exhibited increased mechanical, thermal and gas barrier properties, though they retained their optical clarity. Thus, the Young's modulus of the sample containing 20% clay was increased by 193 times, while the oxygen permeability was decreased about seven times, in regard to the corresponding values of the neat polymer. The obtained results were explored on the basis of nanoscale phenomena and it was concluded that the organized structures and intercalated regions observed on highly loaded samples are attributed to the competitive effect between weaker polymer-polymer interactions in relation to stronger polymer-clay ones.