Conductive Network and β Polymorph Content Evolution Caused by Thermal Treatment in Carbon Nanotubes-BaTiO3 Hybrids Reinforced Polyvinylidene Fluoride Composites

A good dispersion of carbon nanotube (CNT) in polyvinylidene fluoride (PVDF) is realized by using CNT and BaTiO3 (BT) hybrids (H-CNT-BT) with a special core–shell structure. Thus, a high dielectric performance is achieved for the composite (H-CNT-BT/PVDF). Carried by BT, CNT is easy to connect with each other and thus more interface area may be created which helps to achieve an extremely low percolation threshold (fc). Moreover, the dielectric permittivity of the composite near fc is increased more than three times after thermal treatment while dielectric loss remains at a low level. In order to study more comprehensively about the influence of thermal treatment, in situ synchrotron X-ray is used to detect recrystalline behavior of PVDF. Results of wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) show that after thermal treatment, the content of β polymorph has increased nearly double times at the interface of CNT-PVDF, and the thickness of amorphous layers (La) in PVDF’s long p...