Preparation and characterization of poly(vinylalcohol)/modifiedbentonitenanocomposites

This study describes an effective way for the preparation ofwell-dispersed poly(vinylalcohol)(PVA)/ben-tonite and poly(vinylalcohol)/modifiedbentonite nanocomposites with improve dthermal properties.Nanocomposi tes were synthesized byeffectively dispersing the inorganic nanolayers ofbentonite inPVA matrix via the solution intercalation method.Bentonite was calcinated at150 and 650 C and mod-ified with 3-aminopropyltrimethoxysilane (3-APT),dimethylsulfoxide (DMSO)and methanol (MeOH).The surface areas of bentonite and modifiedbentonite samples were measured byBET surface analyzer.In order todetermine thermal stabilities ofPVA and its nanocomposites,itwas used thermogravimetricanalysis (TGA) and differential scanning calorimetry (DSC).The interactions between polymer,PVA,andfilling material,bentonite were determined usi ngFourier transform infrared spectroscopy attenuatedtotal reflectance (FTIR-ATR).The dispersion and exfoliation ofthe clay layers inPVA matrix were exam-ined by X-ray diffraction (XRD)and transmission electron microscopy (TEM).The contact angles ofPVAand its nanocomposites were determined for nanocomposites bysessile drop method.The activationenergie s were calcu lated using the Kissinger method.XRD and TEM results showed that bentonite layerswere dispersed innanoscale and homogenously inPVA matrix.Microscopic and XRD technique srevealedhighly organized regions. Clay content upto5wt.%led tonanocomposites with high degree ofexfolia-tion. Thermograv imetric analysis indicated that introduction ofclay tothe polymer network resultedin anincrease inthermal stability.Activation energy values atboth stages for PVA/bentonite nanocom-posite were higher than those ofpure PVA,indicating that addition ofbentonite particles improves ther-mal stability of PVA.