Thermal effects on the percolation behavior of polyvinylidene fluoride/nickel composites

Abstract

Percolation theory predicts the ideal percolation threshold (P C ) for insulator/conductor composites (ICC) to be at 0.16 of the conductor volume fraction in the composite. In this article, we have investigated the percolation behavior in polyvinylidene fluoride/nickel (Ni) composites by varying the Ni concentration. It is observed that the thermal effect/time of heat treatment play a crucial role in changing the value of P C in a simple random continuum percolative ICC. The effect is attributed to decrease in: (i) intercluster distance, (ii) viscosity of the polymer, and (iii) wetting of the polymer to metal. The heat energy helps the polymer matrix to be melted as a result the metal particles/clusters come closure, that causes an increase in the cluster size of the metal particles.The overall effect is lowering of P C mainly due to decrease in intercluster distance. A drastic enhancement in the dielectric permittivity with increase of metal content is explained using boundary layer capacitive effect arising due to Maxwell-Wagner-Sillars interfacial polarization of accumulated charges at the metal-polymer interfaces and blocking of charge carriers at the insulating boundary. The substantial enhancement of ac conductivity at the P C is attributed to leakage of charge carriers across the insulating barrier.

Role of polymer matrix in large enhancement of dielectric constant in polymer-metal composites

“…These PCC undergo an insulator-metal transition (IMT) at a critical volume fraction of the conductor ðf con Þ called percolation threshold ðf c Þ which is characterized by an abnormal increase in ac conductivity ðr eff Þ and divergence in the real part of e eff in accordance with the percolation theory. 16 [4][5][6][7][8][9][10][11][12][13][14][15] These investigations show scattered values of e eff and f c . The effects of nature of filler, along with their particle size, shape, and process conditions on e eff and f c have been investigated in various PCC.…”

“…The effects of nature of filler, along with their particle size, shape, and process conditions on e eff and f c have been investigated in various PCC. [4][5][6][7][8][9][10][11][12][13][14][15][18][19][20][21][22] However, few studies are oriented towards investigation of (i) what is the role of polymer matrix in increasing the e eff at f c ? (ii) whether the extent of enhancement of e eff at f c depend on the polymer matrix in case of PMC.…”

Filler dependent microstructural and optical properties of PVDF/PEG blends versus PVDF/GO nanocomposites

“…The importance of these materials is mainly due to the complex interfacial region between the ller/polymer giving rise to tremendous variation in their intended physical properties required for various multifunctional applications, due to the large surface area of the llers. They have become very smart materials from the point of energy storage [7][8][9][10][11][12][13], ferroelectrics [14] and multiferroics/magnetoelectrics [15][16][17], magnetodilectrics, [18], optical/optoelectronics [19][20][21][22][23][24], biomedical [25] or any other multifunctional applications, due to their inherent exibility solving the most complicated designing problems. The various types of nano llers used in these PNC are e.g.…”

“…. In the development of polymer dielectrics/ferroelectrics, the varieties of metal and ferroelectric ceramic nano particles have been introduced into the PVDF matrix [7][8][9][10][11][12][13]. In development of polymer multiferroics/magnteoelectrics/magneto-dielectrics, the particulate composites based on various llers have been introduced [15][16][17][18].…”

Filler Dependent Microstructural and Optical Properties of PVDF/PEG Blends Versus PVDF/GO Nanocomposites

“…The importance of these materials is mainly due to the complex interfacial region between the ller/polymer giving rise to tremendous variation in their intended physical properties required for various multifunctional applications, due to the large surface area of the llers. They have become very smart materials from the point of energy storage [7][8][9][10][11][12][13], ferroelectrics [14] and multiferroics/magnetoelectrics [15][16][17], magnetodilectrics, [18], optical/optoelectronics [19][20][21][22][23][24], biomedical [25] or any other multifunctional applications, due to their inherent exibility solving the most complicated designing problems. The various types of nano llers used in these PNC are e.g.…”