POSS
Polyhedral oligomeric silsesquioxane
RNC
Rubber nanocomposites
RTV
Room Temperature Vulcanizing silicone
TDSS
Tetrakis(dimethylsiloxy)silane
TEOS
Tetraethoxysilane
TESPD
Bis-(triethoxysilylpropyl)-disulfane
T g
Glass transition temperature
1 Introduction
Rubber nanocomposites play a very important role among organic–inorganic
hybrid materials. Nanomaterials very often are classified into three categories:
nanoparticles, nanotubes and nanolayers, depending on how many dimensions of
the dispersed particles are in the nanometer scale [1]. Different types of
nanoparticles can be incorporated into the polymer matrix to obtain polymer
nanocomposites, especially rubber nanocomposites. Nanocomposites are materials
whose components (matrix + nanofiller) are mixed at a nanometer scale. The nature
of the nanofillers allows nanocomposites to exhibit different properties in comparison to conventional microcomposites. Rubber nanocomposites, in comparison
with classic rubber composites, are capable of improving the mechanical, chemical
and physical properties, e.g. flame retardance, impact and heat resistance or barrier
properties. These properties can be achieved at very low level loadings of nanofiller
(practically, less than 5 wt%). Therefore, an important characteristic of
nanocomposites is that they require much lower concentrations of filler than that
required conventional microcomposites for similar rheological effects, because of
the nanoparticle’s larger available surface area and the development of a mesostructural polymer-nanoparticle network. These materials possess significantly
increased interfacial interactions between nanoparticles and the polymeric matrix.
It is well known that most polymers exhibit linear viscoelastic behavior under
relatively large strains. For polymeric nanocomposites the linear viscoelastic properties generally increase with the addition of nanofiller. Recently, many researchers
have reported work on nonlinear viscoelastic behavior, including high strain–stress
hysteresis, stress softening, and strain-dependent dynamic modulus. Rubber
nanocomposites exhibit nonlinear viscoelastic behavior in response to dynamic
strain. This nonlinear behavior includes strong shear thinning at relatively low
shear rates or strain-dependent viscoelastic moduli at low strain amplitudes and is
called the Payne effect [2]. This effect is characteristic for filled and nanofilled
polymers in the amorphous state above the glass transition temperature. It was
A.R. Payne who investigated this strain-dependent modulus upon dynamic
straining for rubber containing fillers over 50 years ago [3, 4]. The general interpretation of the nonlinearity in viscoelastic behavior in elastomeric matrix vs filler
systems is connected with filler agglomeration and its network formation, which are
responsible for the higher degree of reinforcement, and the nonlinearity varies with
60
M. Strankowski
Polyhedral oligomeric silsesquioxane
RNC
Rubber nanocomposites
RTV
Room Temperature Vulcanizing silicone
TDSS
Tetrakis(dimethylsiloxy)silane
TEOS
Tetraethoxysilane
TESPD
Bis-(triethoxysilylpropyl)-disulfane
T g
Glass transition temperature
1 Introduction
Rubber nanocomposites play a very important role among organic–inorganic
hybrid materials. Nanomaterials very often are classified into three categories:
nanoparticles, nanotubes and nanolayers, depending on how many dimensions of
the dispersed particles are in the nanometer scale [1]. Different types of
nanoparticles can be incorporated into the polymer matrix to obtain polymer
nanocomposites, especially rubber nanocomposites. Nanocomposites are materials
whose components (matrix + nanofiller) are mixed at a nanometer scale. The nature
of the nanofillers allows nanocomposites to exhibit different properties in comparison to conventional microcomposites. Rubber nanocomposites, in comparison
with classic rubber composites, are capable of improving the mechanical, chemical
and physical properties, e.g. flame retardance, impact and heat resistance or barrier
properties. These properties can be achieved at very low level loadings of nanofiller
(practically, less than 5 wt%). Therefore, an important characteristic of
nanocomposites is that they require much lower concentrations of filler than that
required conventional microcomposites for similar rheological effects, because of
the nanoparticle’s larger available surface area and the development of a mesostructural polymer-nanoparticle network. These materials possess significantly
increased interfacial interactions between nanoparticles and the polymeric matrix.
It is well known that most polymers exhibit linear viscoelastic behavior under
relatively large strains. For polymeric nanocomposites the linear viscoelastic properties generally increase with the addition of nanofiller. Recently, many researchers
have reported work on nonlinear viscoelastic behavior, including high strain–stress
hysteresis, stress softening, and strain-dependent dynamic modulus. Rubber
nanocomposites exhibit nonlinear viscoelastic behavior in response to dynamic
strain. This nonlinear behavior includes strong shear thinning at relatively low
shear rates or strain-dependent viscoelastic moduli at low strain amplitudes and is
called the Payne effect [2]. This effect is characteristic for filled and nanofilled
polymers in the amorphous state above the glass transition temperature. It was
A.R. Payne who investigated this strain-dependent modulus upon dynamic
straining for rubber containing fillers over 50 years ago [3, 4]. The general interpretation of the nonlinearity in viscoelastic behavior in elastomeric matrix vs filler
systems is connected with filler agglomeration and its network formation, which are
responsible for the higher degree of reinforcement, and the nonlinearity varies with
60
M. Strankowski