378
L. L. Vovchenko et al.
Nanocomposites are heterostructures with a large number of interphase boundaries of carbon nanotubes/polymers with a certain spatial distribution of the
disperse phase (1D or 2D nanocarbon particles) in the polymer matrix; both the
microstructure of such composites and their properties are significantly dependent on the content of nanofillers. So, as it was shown in [9] at studies of
graphene/poly(vinylidene fluoride) composites, there are still some challenges
in development of nanocarbon/polymer composites. First, it is difficult to tailor
the dielectric properties of the composites by changing the volume fraction of
nanocarbon, since a small change in the conductive filler content would cause a
dramatic variation of percolation network near the percolation threshold. Second,
the dielectric loss in the conductive filler/polymer composites always appears to
be very large due to the leakage current in composites after percolation threshold.
Third, poor compatibility between the nanocarbon and polymers prevents the
formation of a homogeneous composite that leads to the harmful agglomeration
of nanocarbon particles. To solve these problems, it is obvious that the controllable
dispersibility of nanocarbon particles in polymer matrix should be primarily realized
since the nanofiller dispersion is decisive to the electrical, mechanical, thermal, and
other properties of nanocomposites.
The electrical transport and propagation of electromagnetic waves in composite
heterostructures is a field of great fundamental importance in diverse applications,
with potential in aeronautics, space, and telecommunications [4, 10]. Achieving
an understanding of the properties and behavior of a wide range of composite
heterostructures has therefore become one of the main themes in material research.
Inhomogeneity and boundary conditions in heterogeneous media strongly influence
on effective properties of composite such as electrical conductivity, dielectric
permittivity, and magnetic permeability. As it was noted in [4, 11] at modeling and
calculation of physical properties of mentioned composites, it is necessary to take
into account the collective effects that are operative at high concentrations of filler
particles and consider the complicated microstructures of real composite materials
for obtaining of predictive values of effective parameters of composites [12].
In recent years in many studies [13–16], it was shown that multicomponent
composites have advantages in mechanical property and electrical and thermal
conductivities. Multiphase composites with several different fillers in the matrix are
very interesting in order to find the so-called synergy effect. Often, the distribution
of different fillers within the polymer matrix can be favorable, and electrical
transport can occur in different filler networks together. When this occurs, the
percolation threshold can decrease dramatically. Many investigations of synergy
effects were performed in CNT/CB composites, and a significant decrease in the
percolation threshold, in comparison with CB composites, was observed [17, 18].
However, it is not clear whether multicomponent composites also have the
advantage in preparing materials with high tunable dielectric permittivity, because
dielectric property and conductivity have a fundamental difference. Specifically, the
dielectric property reflects the ability to store and consume electrostatic energy in an
alternating electric field of a material, while the electric conductivity of a material
refers to the ability of transporting electric charges. For a conductor/polymer
L. L. Vovchenko et al.
Nanocomposites are heterostructures with a large number of interphase boundaries of carbon nanotubes/polymers with a certain spatial distribution of the
disperse phase (1D or 2D nanocarbon particles) in the polymer matrix; both the
microstructure of such composites and their properties are significantly dependent on the content of nanofillers. So, as it was shown in [9] at studies of
graphene/poly(vinylidene fluoride) composites, there are still some challenges
in development of nanocarbon/polymer composites. First, it is difficult to tailor
the dielectric properties of the composites by changing the volume fraction of
nanocarbon, since a small change in the conductive filler content would cause a
dramatic variation of percolation network near the percolation threshold. Second,
the dielectric loss in the conductive filler/polymer composites always appears to
be very large due to the leakage current in composites after percolation threshold.
Third, poor compatibility between the nanocarbon and polymers prevents the
formation of a homogeneous composite that leads to the harmful agglomeration
of nanocarbon particles. To solve these problems, it is obvious that the controllable
dispersibility of nanocarbon particles in polymer matrix should be primarily realized
since the nanofiller dispersion is decisive to the electrical, mechanical, thermal, and
other properties of nanocomposites.
The electrical transport and propagation of electromagnetic waves in composite
heterostructures is a field of great fundamental importance in diverse applications,
with potential in aeronautics, space, and telecommunications [4, 10]. Achieving
an understanding of the properties and behavior of a wide range of composite
heterostructures has therefore become one of the main themes in material research.
Inhomogeneity and boundary conditions in heterogeneous media strongly influence
on effective properties of composite such as electrical conductivity, dielectric
permittivity, and magnetic permeability. As it was noted in [4, 11] at modeling and
calculation of physical properties of mentioned composites, it is necessary to take
into account the collective effects that are operative at high concentrations of filler
particles and consider the complicated microstructures of real composite materials
for obtaining of predictive values of effective parameters of composites [12].
In recent years in many studies [13–16], it was shown that multicomponent
composites have advantages in mechanical property and electrical and thermal
conductivities. Multiphase composites with several different fillers in the matrix are
very interesting in order to find the so-called synergy effect. Often, the distribution
of different fillers within the polymer matrix can be favorable, and electrical
transport can occur in different filler networks together. When this occurs, the
percolation threshold can decrease dramatically. Many investigations of synergy
effects were performed in CNT/CB composites, and a significant decrease in the
percolation threshold, in comparison with CB composites, was observed [17, 18].
However, it is not clear whether multicomponent composites also have the
advantage in preparing materials with high tunable dielectric permittivity, because
dielectric property and conductivity have a fundamental difference. Specifically, the
dielectric property reflects the ability to store and consume electrostatic energy in an
alternating electric field of a material, while the electric conductivity of a material
refers to the ability of transporting electric charges. For a conductor/polymer