Tuned dielectric and percolation behavior of cold-pressed polyvinyledene fluoride nanocomposites caused by Ni and BaTiO3 fillers

Abstract

The dielectric and percolation behavior of polymer nanocomposites (PNC) comprising of polyvinylidene fluoride (PVDF)/nanocrystalline nickel (n-Ni) [conducting filler] and PVDF/n-BaTiO3 [ferroelectric insulating filler], prepared under the novel cold press method are compared. Higher effective dielectric constants (ɛeff) of 2400 and 400 at 40 Hz with volume fractions of filler fcon = 0.28 and $$f_{{{\text{BaTiO}}_{3} }} = 0.60$$ were observed, respectively. PVDF/n-Ni composites show percolation behavior associated with insulator to metal transition (IMT) at the percolation threshold (fc), while PVDF/n-BaTiO3 shows an effective electrical behavior due to the sum effect without showing any IMT. The drastic modulation in their dielectric, electrical and percolation behavior are attributed to the nature of filler present in them and has been explained by Percolation theory, Yamada model and VRH models. The universality and non-universality of exponents have been understood within the framework of the above models, the geometry of the fillers and the process conditions. Cold-pressed PNC based on ferroelectric filler are of superior quality for dielectric applications.