Hybrid Polyvinylidene Fluoride/Nanoclay/ MWCNT Nanocomposites: PVDF Crystalline Transformation

In this work the coexistence effect of Cloisite 30B and multi-walled carbon nanotubes (MWCNT) on the crystal transformation of the polyvinylidene fluoride (PVDF) matrix is reported. It was found that at a constant rate of 3% (by weight) total modification, a higher percentage of beta crystal was evolved in PVDF matrix as compared with that of 3% (by weight) of each nanomaterial in the whole nanocomposite system. These changes in the crystalline structure were quantitatively and qualitatively studied using FTIR and WXRD techniques, respectively. The FTIR technique confirmed the formation of 80%, 71% and 84% of beta crystal for the three prepared composites. The small-angle X-ray scattering (SAXS) technique revealed a 10-time increase in the d-spacing of the nanoclay in nanocomposites as compared with that in raw nanocaly. The morphology of the nanomaterials and the state of dispersion were investigated using SEM and TEM techniques. The synergism observed was assigned to differences in surface conformations and aspect ratio of the nanomaterials. These nanocomposites ensured formation of beta crystals without any need to apply strain. Meanwhile, the piezoelectric constant (d33) of the hot-pressed samples was found to be zero. To attain piezopyroelectric characteristics, there was a need to cold-drawing, probably by small- er strain which resulted in better mechanical properties and anisotropy of the resulting hybrid nanocomposite.