SBR/BR based composites in the temperature range of 50–60
C) compared to the
rolling resistance of SBR vulcanizates. EG/i-MG containing rubber composites in
the presence of CB showed superior storage modulus, antiskid properties and lower
rolling resistance compared to the only CB loaded rubber composites, which was
due to the better interactions and interfacial adhesion between i-MG sheets and the
rubber matrices [115].
5 Conclusions
The properties of rubber-rubber blend composites depend on the size and shape and
concentration of nano particles and their interactions with the individual rubber
matrix. The interaction between the filler and the matrix are improved by surface
modification. In the rubber industry the uniform distribution of nano particles is
considered to be important as it affects the mechanical properties and performance
of the composite. For rubber-rubber blend composites fillers like carbon black
prefer to migrate to less polar, less viscous rubber phase whereas silica and clay
particles migrate to more polar rubber phase. CNTs mainly reside in the highly
polar and non-polar rubbers but not in weakly polar ones. The Tg remain unaltered
for a completely incompatible blend. In the case of partially compatible blends, the
Tgs of the blend components are expected to shift towards each other as compared
with the pure components. Shifting of Tg of polymers to lower or higher values in a
blend depends on the polarity difference and the difference in the thermal expansion coefficient of the respective polymers in the blend.
The storage modulus of unfilled rubbers, E
0 , depends on frequency and temperature and is independent of the deformation amplitude. In contrast, E
0 for the filled
rubber shows a significant dependency on the dynamic deformation, here the value
considerably decreases with an increasing strain amplitude. This non-linear behaviour of filled rubbers is known as Payne effect and has been explained by the
existence of a filler network in the rubber matrix above the percolation threshold.
With increasing strain amplitude the filler network gets broken and results in
lowering of the E
0 value. The amount and morphology of the fillers play a major
role in the Payne effect. The Payne effect is assumed to arise from the elementary
mechanism consisting of adsorption-desorption of macromolecular chains from the
filler surface. It is found that due to the small particle size and high specific surface
area, nanofiller forms stronger and more developed filler-filler network and the
breakdown of these networks results in larger Payne effect. At low loading, there is
not much variation in storage modulus, loss modulus and loss tangent compared to
gum vulcanizates. But at higher loading, pronounced effect has been observed for
the rubber nanocomposites. There is a gradual increase in E
0 of rubber blends with
increase in filler content in all temperature regions. In the rubbery region the
polymer–filler, filler–filler and filler aggregate interactions have a pronounced
effect on storage modulus. With an increase in temperature E
0 of rubber blend
130
A.B. Nair et al.
C) compared to the
rolling resistance of SBR vulcanizates. EG/i-MG containing rubber composites in
the presence of CB showed superior storage modulus, antiskid properties and lower
rolling resistance compared to the only CB loaded rubber composites, which was
due to the better interactions and interfacial adhesion between i-MG sheets and the
rubber matrices [115].
5 Conclusions
The properties of rubber-rubber blend composites depend on the size and shape and
concentration of nano particles and their interactions with the individual rubber
matrix. The interaction between the filler and the matrix are improved by surface
modification. In the rubber industry the uniform distribution of nano particles is
considered to be important as it affects the mechanical properties and performance
of the composite. For rubber-rubber blend composites fillers like carbon black
prefer to migrate to less polar, less viscous rubber phase whereas silica and clay
particles migrate to more polar rubber phase. CNTs mainly reside in the highly
polar and non-polar rubbers but not in weakly polar ones. The Tg remain unaltered
for a completely incompatible blend. In the case of partially compatible blends, the
Tgs of the blend components are expected to shift towards each other as compared
with the pure components. Shifting of Tg of polymers to lower or higher values in a
blend depends on the polarity difference and the difference in the thermal expansion coefficient of the respective polymers in the blend.
The storage modulus of unfilled rubbers, E
0 , depends on frequency and temperature and is independent of the deformation amplitude. In contrast, E
0 for the filled
rubber shows a significant dependency on the dynamic deformation, here the value
considerably decreases with an increasing strain amplitude. This non-linear behaviour of filled rubbers is known as Payne effect and has been explained by the
existence of a filler network in the rubber matrix above the percolation threshold.
With increasing strain amplitude the filler network gets broken and results in
lowering of the E
0 value. The amount and morphology of the fillers play a major
role in the Payne effect. The Payne effect is assumed to arise from the elementary
mechanism consisting of adsorption-desorption of macromolecular chains from the
filler surface. It is found that due to the small particle size and high specific surface
area, nanofiller forms stronger and more developed filler-filler network and the
breakdown of these networks results in larger Payne effect. At low loading, there is
not much variation in storage modulus, loss modulus and loss tangent compared to
gum vulcanizates. But at higher loading, pronounced effect has been observed for
the rubber nanocomposites. There is a gradual increase in E
0 of rubber blends with
increase in filler content in all temperature regions. In the rubbery region the
polymer–filler, filler–filler and filler aggregate interactions have a pronounced
effect on storage modulus. With an increase in temperature E
0 of rubber blend
130
A.B. Nair et al.