is usually assumed to be isotropic. The Payne effect becomes more pronounced at
higher silica loading. The filler characteristics such as particle size, specific surface
area, and the surface structural features were found to be the key parameters
influencing the Payne effect. A nonlinear decrease in storage modulus with increasing strain was observed for unfilled compounds also. The results reveal that the
mechanism includes the breakdown of different networks namely the filler-filler
network, the weak polymer-filler network, the chemical network, and the entanglement network. The model of variable network density proposed by Maier and
Goritz has been applied to explain the nonlinear behavior. The model fits well
with the experimental results. The interaction between epoxidized elastomeric
matrix and silica as filler was extremely improved, even in the presence of very
low content of epoxy groups into the polymer chain.
Keywords Rubber reinforcement • Elastomers • Rheology
1 Introduction
The role of active fillers (carbon black, silica, CNT) has been studied in the rubber
matrix for a better understanding of the rubber performance and the mechanism of
reinforcement. The elastomer reinforcement by using filler needs, generally, strong
physical interactions between the segments of the polymer chain and the filler
surface [1, 2]. In some cases the reinforcement is supported by chemical bond of
the polymer with the filler surface, by using coupling agent [3, 4]. This interaction
can strongly affect the physical properties, as well as the dynamic-mechanical
properties. The modulus of an unfilled compound practically has no change with
the variation in the deformation amplitude, but this modulus decrease significantly
to filled rubber compounds [5]. The non-linear dependency of G
0 as a function of
deformation amplitude (Payne effect) can be explained due to the breakdown of the
filler network considering a continuous increase in the periodic deformation [6,
7]. Through the improvement of the polymer-filler interaction and filler dispersion,
the dependency of the modulus as a function of variation in deformation amplitude
becomes to be less pronounced.
The dynamic properties of filled elastomers have been a subject of active
research because they affect the performance of tires such as skid, traction, and
rolling resistance to cite but a few [8–11].
The “Payne effect” [9] has been extensively investigated because it directly
impacts the fuel consumption. From a phenomenological point of view, beyond a
strain higher than a few 0.1 %, the storage modulus of filled rubber departs from a
plateau value G
0
0 and collapse to a minimum value G
0
1 . The decrease in the storage
modulus is accompanied by a maximum of the loss modulus, G
00 . The amplitude of
the Payne effect, ΔG) G
0
0 À G
0
1 increases with the filler content, the specific surface
of the filler [12] and strongly depends on the surface properties of the fillers and its
dispersion [13] within the matrix. On the contrary it decreases with temperature
194
G. Markovic ´ et al.
higher silica loading. The filler characteristics such as particle size, specific surface
area, and the surface structural features were found to be the key parameters
influencing the Payne effect. A nonlinear decrease in storage modulus with increasing strain was observed for unfilled compounds also. The results reveal that the
mechanism includes the breakdown of different networks namely the filler-filler
network, the weak polymer-filler network, the chemical network, and the entanglement network. The model of variable network density proposed by Maier and
Goritz has been applied to explain the nonlinear behavior. The model fits well
with the experimental results. The interaction between epoxidized elastomeric
matrix and silica as filler was extremely improved, even in the presence of very
low content of epoxy groups into the polymer chain.
Keywords Rubber reinforcement • Elastomers • Rheology
1 Introduction
The role of active fillers (carbon black, silica, CNT) has been studied in the rubber
matrix for a better understanding of the rubber performance and the mechanism of
reinforcement. The elastomer reinforcement by using filler needs, generally, strong
physical interactions between the segments of the polymer chain and the filler
surface [1, 2]. In some cases the reinforcement is supported by chemical bond of
the polymer with the filler surface, by using coupling agent [3, 4]. This interaction
can strongly affect the physical properties, as well as the dynamic-mechanical
properties. The modulus of an unfilled compound practically has no change with
the variation in the deformation amplitude, but this modulus decrease significantly
to filled rubber compounds [5]. The non-linear dependency of G
0 as a function of
deformation amplitude (Payne effect) can be explained due to the breakdown of the
filler network considering a continuous increase in the periodic deformation [6,
7]. Through the improvement of the polymer-filler interaction and filler dispersion,
the dependency of the modulus as a function of variation in deformation amplitude
becomes to be less pronounced.
The dynamic properties of filled elastomers have been a subject of active
research because they affect the performance of tires such as skid, traction, and
rolling resistance to cite but a few [8–11].
The “Payne effect” [9] has been extensively investigated because it directly
impacts the fuel consumption. From a phenomenological point of view, beyond a
strain higher than a few 0.1 %, the storage modulus of filled rubber departs from a
plateau value G
0
0 and collapse to a minimum value G
0
1 . The decrease in the storage
modulus is accompanied by a maximum of the loss modulus, G
00 . The amplitude of
the Payne effect, ΔG) G
0
0 À G
0
1 increases with the filler content, the specific surface
of the filler [12] and strongly depends on the surface properties of the fillers and its
dispersion [13] within the matrix. On the contrary it decreases with temperature
194
G. Markovic ´ et al.