improved properties of NR/layered filler nanocomposites can are attributed to
microstructural and morphological changes induced by filler in the NR matrix
during crystallization. All of these factors during deformation contribute to the
formation of a network structure containing cross-linked chemical chains,
nanofiller, and crystallizable networks in the NR/filler nanocomposite. Dishovsky
et al. [7] have reported that carbon black filled NR-containing graphene
nanoparticles (GNPs) were found to improve the dielectric properties and microwave properties, viz., coefficient of absorption and reflection of the electromagnetic
waves and electromagnetic interference shielding effectiveness. Stiffness improvement by thermally reduced graphene oxide (TRG) was found to be more pronounced for elastomers [8], such as NR and styrene butadiene rubber (SBR), due
to the higher stiffness between the matrix and the filler.
Introduction of fillers can affect the morphology and change the viscoelastic
behaviour of the polymers by introducing filler-matrix interactive forces or restriction of polymer chain mobility by the presence of filler particles. It is thus of much
interest to study the viscoelastic behaviour of polymers filled with nanosized fillers,
where the nanoparticle size allows interactions with polymer at the molecular level.
Dynamic mechanical thermal analysis (DMTA) or Dynamic mechanical analysis (DMA) measures the response of a given material to an oscillatory deformation
as a function of temperature. DMA results are composed of three parameters: (a) the
storage modulus (E
0 ), corresponding to the elastic response to the deformation,
(b) the loss modulus (E
00 ), the plastic response to the deformation and (c) tan δ; the
ratio (E
00 /E
0 ), a measure of the damping behaviour which is useful for determining
the occurrence of molecular mobility transitions, such as the glass transition
temperature (Tg). DMA can provide reliable information over the relaxation
behaviour of the materials.
1.1 Rubber Blends
By blending different polymers, it is possible to bring the properties of the individual components to a single material. The phenomenon of blending can be
implemented more rapidly and economically. This technique has helped to develop
many new materials, which are of good quality and are cheaper in market. The
fundamental justification for blending two or more elastomers is acquisition of
different features exhibited by vulcanizates of the component elastomers in a single
composite. Unfortunately, it has been found that co-vulcanization leads to reduction
in the mechanical strength of the vulcanizate compared with its expected values.
Homogeneity of mixing and retention of the compatibility during the vulcanization
are the most relevant issues although micro-heterogeneity is usually desirable to
retain the individual properties of the respective elastomer components remaining
in a blend.
Mixtures and blends occur at different hierarchical scales in the material range
employed in the rubber industry. Composite products such as tires, hoses, belts, and
88
A.B. Nair et al.
microstructural and morphological changes induced by filler in the NR matrix
during crystallization. All of these factors during deformation contribute to the
formation of a network structure containing cross-linked chemical chains,
nanofiller, and crystallizable networks in the NR/filler nanocomposite. Dishovsky
et al. [7] have reported that carbon black filled NR-containing graphene
nanoparticles (GNPs) were found to improve the dielectric properties and microwave properties, viz., coefficient of absorption and reflection of the electromagnetic
waves and electromagnetic interference shielding effectiveness. Stiffness improvement by thermally reduced graphene oxide (TRG) was found to be more pronounced for elastomers [8], such as NR and styrene butadiene rubber (SBR), due
to the higher stiffness between the matrix and the filler.
Introduction of fillers can affect the morphology and change the viscoelastic
behaviour of the polymers by introducing filler-matrix interactive forces or restriction of polymer chain mobility by the presence of filler particles. It is thus of much
interest to study the viscoelastic behaviour of polymers filled with nanosized fillers,
where the nanoparticle size allows interactions with polymer at the molecular level.
Dynamic mechanical thermal analysis (DMTA) or Dynamic mechanical analysis (DMA) measures the response of a given material to an oscillatory deformation
as a function of temperature. DMA results are composed of three parameters: (a) the
storage modulus (E
0 ), corresponding to the elastic response to the deformation,
(b) the loss modulus (E
00 ), the plastic response to the deformation and (c) tan δ; the
ratio (E
00 /E
0 ), a measure of the damping behaviour which is useful for determining
the occurrence of molecular mobility transitions, such as the glass transition
temperature (Tg). DMA can provide reliable information over the relaxation
behaviour of the materials.
1.1 Rubber Blends
By blending different polymers, it is possible to bring the properties of the individual components to a single material. The phenomenon of blending can be
implemented more rapidly and economically. This technique has helped to develop
many new materials, which are of good quality and are cheaper in market. The
fundamental justification for blending two or more elastomers is acquisition of
different features exhibited by vulcanizates of the component elastomers in a single
composite. Unfortunately, it has been found that co-vulcanization leads to reduction
in the mechanical strength of the vulcanizate compared with its expected values.
Homogeneity of mixing and retention of the compatibility during the vulcanization
are the most relevant issues although micro-heterogeneity is usually desirable to
retain the individual properties of the respective elastomer components remaining
in a blend.
Mixtures and blends occur at different hierarchical scales in the material range
employed in the rubber industry. Composite products such as tires, hoses, belts, and
88
A.B. Nair et al.