air springs are composed of metal wire, textile cord, and elastomeric compounds,
which form a rubber matrix. The rubber matrix itself is a mixture of elastomer,
filler, and plasticizer etc. The elastomer phase is often a blend of different elastomers. However, there are technological problems arising from some types of
mutual incompatibility that exist between dissimilar elastomers. Three main types
of incompatibility have generally been noted: the thermodynamic incompatibility,
incompatibility due to viscosity mismatch, and incompatibility due to the cure rate
mismatch [9].
Kim and Hamed [10] prepared a vulcanizate based on a 50/50 natural rubber/cisbutadiene rubber (NR/cis-BR).This blend has been found to retain the rupture
resistance property of NR vulcanizate and resistance to slow fatigue crack growth
property of cis-BR vulcanizate. Botros et al. [11] studied the properties of acrylonitrile butadiene rubber/polychloroprene rubber blend (NBR/CR). The blend was
found to possess the thermal resistance of CR and the oil resistance of NBR.
Natural rubber was blended with synthetic nonpolar rubbers like styrene butadiene rubber (SBR), butadiene rubber (BR) and EPDM and polar rubbers like NBR
and CR [12]. NR/SBR and NR/BR blends were compatible, while NR/EPDM,
NR/NBR and NR/CR blends were incompatible.
Blends have been developed to meet several industrial requirements such as the
need of easier processing and broadening of the properties range, either by varying
the type, or by relative amounts or morphology of each component [13, 14].
1.2 Rubber Blend Composites
Addition of fillers to rubber blend has been found to cause severe changes in the
properties of the blend. It has been known that the distribution of filler in rubber
blends is one of the most important factors affecting the physical properties of
rubber final products. It has generally been believed that the main factors controlling the filler distributed in each phase of the blends are the nature of rubber, mixing
sequence, and filler–rubber interaction.
Sircar et al. [15] studied the effect of heterogeneous carbon black distribution on
the properties of a BR/SBR blend and a BR/NR blend. Varying the sequence of
carbon black addition caused the distribution of the carbon black to change. They
found that superior hysteresis properties of the blend were obtained when most of
the carbon black was in the BR phase. Massie et al. [16] studied the distribution of
carbon black in NR/BR blends and found that N550 black has no preference for
either the NR or the BR. However, if the blend was prepared by carrying out a phase
mixing technique, the majority of the black remained in the polymer to which it was
initially added. It was also found that the cut-growth resistance of the rubber blends
in which carbon black is mainly in the BR phase is poorer than that of the blend with
evenly distributed black.
Besides the mixing sequence, the distributions of carbon black in elastomer
blends are affected by viscosity, degree of unsaturation, and polarity of rubbers. For
Non-linear Viscoelastic Behaviour of Rubber-Rubber Blend Composites and. . .
89
which form a rubber matrix. The rubber matrix itself is a mixture of elastomer,
filler, and plasticizer etc. The elastomer phase is often a blend of different elastomers. However, there are technological problems arising from some types of
mutual incompatibility that exist between dissimilar elastomers. Three main types
of incompatibility have generally been noted: the thermodynamic incompatibility,
incompatibility due to viscosity mismatch, and incompatibility due to the cure rate
mismatch [9].
Kim and Hamed [10] prepared a vulcanizate based on a 50/50 natural rubber/cisbutadiene rubber (NR/cis-BR).This blend has been found to retain the rupture
resistance property of NR vulcanizate and resistance to slow fatigue crack growth
property of cis-BR vulcanizate. Botros et al. [11] studied the properties of acrylonitrile butadiene rubber/polychloroprene rubber blend (NBR/CR). The blend was
found to possess the thermal resistance of CR and the oil resistance of NBR.
Natural rubber was blended with synthetic nonpolar rubbers like styrene butadiene rubber (SBR), butadiene rubber (BR) and EPDM and polar rubbers like NBR
and CR [12]. NR/SBR and NR/BR blends were compatible, while NR/EPDM,
NR/NBR and NR/CR blends were incompatible.
Blends have been developed to meet several industrial requirements such as the
need of easier processing and broadening of the properties range, either by varying
the type, or by relative amounts or morphology of each component [13, 14].
1.2 Rubber Blend Composites
Addition of fillers to rubber blend has been found to cause severe changes in the
properties of the blend. It has been known that the distribution of filler in rubber
blends is one of the most important factors affecting the physical properties of
rubber final products. It has generally been believed that the main factors controlling the filler distributed in each phase of the blends are the nature of rubber, mixing
sequence, and filler–rubber interaction.
Sircar et al. [15] studied the effect of heterogeneous carbon black distribution on
the properties of a BR/SBR blend and a BR/NR blend. Varying the sequence of
carbon black addition caused the distribution of the carbon black to change. They
found that superior hysteresis properties of the blend were obtained when most of
the carbon black was in the BR phase. Massie et al. [16] studied the distribution of
carbon black in NR/BR blends and found that N550 black has no preference for
either the NR or the BR. However, if the blend was prepared by carrying out a phase
mixing technique, the majority of the black remained in the polymer to which it was
initially added. It was also found that the cut-growth resistance of the rubber blends
in which carbon black is mainly in the BR phase is poorer than that of the blend with
evenly distributed black.
Besides the mixing sequence, the distributions of carbon black in elastomer
blends are affected by viscosity, degree of unsaturation, and polarity of rubbers. For
Non-linear Viscoelastic Behaviour of Rubber-Rubber Blend Composites and. . .
89