Comparation of barium titanate and multi-walled carbon nanotubes modified PVDF composites: A perspective of dielectric, crystalline, rheological and mechanical properties

Ceramic powders and conductive particles are the two most used functional fillers for preparing dielectric polymer composites. In this work, barium titanate (BT) and multi-walled carbon nanotubes (MWCNT) were mixed in polyvinylidene fluoride (PVDF) by melt blending. The crystal structure, thermodynamic behavior, dielectric, rheological and mechanical properties of PVDF/BT and PVDF/MWCNT composites were systematically studied and compared. It was found that the volume addition of BT was about 100 times that of MWCNT when dielectric constant (ε′) of composites was the same level. For example, the ε′ of PVDF/BT and PVDF/MWCNT were 68.9 (10² Hz) and 70.4 (10² Hz) when the content of BT and MWCNT were 50 vol% and 0.5 vol%, respectively. However, with the addition of 0.5 vol% MWCNT, the dielectric loss (tanδ) of PVDF/MWCNT was significantly higher than that of PVDF/BT. Additionally, BT had a substantial impact on the crystalline and rheological properties, and worsened the mechanical performance of PVDF/BT. Conversely, MWCNT exerted minimal effects on the crystalline and rheological properties, but enhanced the impact and tensile strength of PVDF/MWCNT.