PVDF/BaTiO₃/carbon nanotubes ternary nanocomposites prepared by ball milling: Piezo and dielectric responses

Abstract

Nanocomposites based on poly(vinylidene fluoride) (PVDF) filled with barium titanate, BaTiO 3 , (BT) particles, and multiwalled carbon nanotubes (MWCNTs) were prepared by high-energy ball milling (HEBM) and subsequent hot pressing. This method of materials preparation allowed obtaining uniform dispersions of the nanofillers. The influence of the particles on the polymer structure and morphology was studied. To understand the origin of changes in the PVDF properties, thermal and electrical behaviors of the PVDF/BT/MWCNT nanocomposites were studied as a function of composition. The addition of BT, MWCNT, or its mixture had not any influence on the PVDF polymorphism. However, calorimetric results pointed out that the presence of the nanofillers exerted nucleation mainly ascribed to the surface to volume ratio of the nanoparticles. The capacitance of the composites increased as the nanofiller content increased, being the effect mainly dependent on the surface to volume ratio of the nanoparticles. The dielectric behavior of the materials as a function of frequency was modeled by a Debye equivalent circuit only below the percolation threshold respect to the amount of MWCNT. The piezoelectric behavior of the ternary nanocomposites was highly affected by the incorporation of the nanofillers only when high dielectric losses occurred above the percolation threshold.

Magnetoelectric Polymer-Based Nanocomposites with Magnetically Controlled Antimicrobial Activity

“…The PVDF β-phase can be obtained through the application of mechanical stretching on PVDF α-phase materials at temperatures close to ≈80 °C through polarization under high electric fields or by crystallizing the polymer at room temperature . Nevertheless, the formation of polar phase crystals in PVDF can also be obtained by incorporating fillers in the polymer matrix, including BaTiO 3 , , clays, hydrated ionic salts, ionic liquids, TiO 2 , and nanostructures of ferrite, − among others. Thus, the nanostructures used to impart the antimicrobial effect may also be used to impart electroactive properties to the materials.…”

Synergistic Effect Based on Enhanced Local Shear Forces in PVDF/TiO2/CNT Ternary Composites

“…24,26 Interfacial polarization is caused by the accumulation of moving charges at a two-phase interface with different conductivities or dielectric constants in a heterogeneous system, which should be infinite above the percolation threshold of the conductivity. 24 In PVDF/CNT binary composites, the agglomerated CNTs reduce the available contact areas and increase the percolation threshold of the conductivity. However, in the PVDF/TiO 2 /CNT composites, the well-dispersed hybrid fillers can increase the number of nanocapacitors represented by CNT-induced macrodipoles, and especially the available contact area between the polymer/particle interface.…”

“…Gonzaĺez-Benito et al fabricated PVDF/barium titanate (BaTiO 3 )/CNT ternary nanocomposites by ball milling and hot pressing. 24 In T h i s c o n t e n t i s this case, the combinational use of BaTiO 3 and CNTs provided a high dielectric constant and a low dielectric loss for PVDF/BaTiO 3 /CNT ternary nanocomposites without compromising their piezoelectric properties below the percolation threshold. Vovchenko et al found that graphite nanoplate (GNP)/titanium oxide (TiO 2 )/epoxy ternary composites are characterized by the lower percolation threshold and enhanced electrical conductivity compared to GNP/epoxy binary composites.…”

Polymeric Materials with Antibacterial Activity: A Review

“…Additionally, Poly(vinylidene fluoride), PVDF and its copolymers are piezoelectric materials with good physical and mechanical properties [ 88 ]. The piezoelectric response of this polymer depends on the crystalline phases, whereas the morphology and mechanical properties depend on its crystallinity [ 88 , 89 , 90 , 91 ]. A good correlation in piezoelectric response was obtained for PVDF with low loadings of AgNPs (0.4%), showing their potential for the design of self-powering devices used as nano-generators with antibacterial properties.…”