Graphite nanoplatelets and/or barium titanate/polymer nanocomposites: fabrication, thermomechanical properties, dielectric response and energy storage

Abstract

Epoxy composites reinforced with (1) micro-size barium titanate (BaTiO₃), (2) nano-size BaTiO₃, (3) graphite nanoplatelets (GNP)_, (4) combination of micro and nano BaTiO₃ and (5) combination of BaTiO₃ and GNP were fabricated and studied, in terms of the type, size and amount of the filler content. Scanning electron microscopy and X-ray diffraction spectra were employed for the investigation of the systems’ morphology. Dynamic mechanical analysis, static mechanical tests and broadband dielectric spectroscopy were used in order to study the properties of the produced systems. Reinforced systems exhibit higher values of storage modulus and dielectric permittivity compared to neat epoxy. Dielectric spectra reveal the presence of two relaxation processes arising from the glass to rubber transition of the polymer matrix (α-mode), and the re-orientation of polar side groups of the polymer chains (β-mode). Finally, the energy storage efficiency of the prepared composite systems was examined in terms of the energy density as a function of the temperature, frequency, type, size and amount of the employed filler.

Keywords:

• exfoliated graphite nanoplatelets
• barium titanate
• polymer nanocomposites
• dielectric properties
• thermomechanical properties
• energy storage

Additional information

Funding

This research has been co-financed by the European Union (European Social Fund – ESF) and Greek national funds through the Operational Program ‘Education and Lifelong Learning’ of the National Strategic Reference Framework (NSRF) – Research Funding Program: THALES [grant number MIS 379346].