Comparison of the effects of graphene and nanoclay nanosheets on crystalline structure of polyvinylidene fluoride
Subject Areas : نانومواد و پلیمرهای هوشمند
Ali Akbar
Yousefi
1
(Department of Plastics, Iran Polymer and Petrochemical Institute)
Keywords: Morphology, Graphene, PVDF, Cloisite 30B, surface free energy,
Abstract :
An extensive review of the literature showed that both graphene and Cloisite 30B nanosheets are widelyemployed to modify the crystalline structure and piezoelectic properties of polyvinylidene fluoride (PVDF).Due to the similarity in the geometry of these nanoparticles a comparative study is reported to find the stemsof difference in their effects on crystalline structure of PVDF. Scanning electron microscopy (SEM) of thesecomposites showed that large and wide graphene particles are dispersed in PVDF matrix whereas theirthickness is well below 100 nanometers. Meanwhile, a careful inspection of SEM micrographs of Cloisite 30Bloaded composites revealed existence of smaller particles with almost the same particles thicknesses. Bothtechniques of Fourier transform infrared (FT-IR) spectroscopy and wide angle X-ray diffraction (WXRD)witnessed changes in the crystalline structure of PVDF. The overall finding was that Cloisite 30B improvesthe polar beta phase of PVDF crystals, whereas a revers effect was found in the presence of graphenenanosheets. These observations were accounted for by differences in surface geometry and surface free energy(surface tension and interfacial tension). Based on the data available for surface properties of these twonanosheets it was found that surface properties of Cloisite 30B is very close to those of PVDF, whereas thesurface properties of graphene are far from those of PVDF. Also a lower interfacial tension was found to beactive in PVDF-Cloisite 30B system compared to that operative in PVDF-graphene system. An intimateinterface along with proper surface texture led to higher content of PVDF’s beta crystals in case of Cloisite30B nanocomposite.
