• Elastomers and Composites
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• v.37 no.4
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• pp.217-223
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• 2002

Silica-filled rubber compounds show poor filler dispersion and slow cure characteristics compared to carbon black-filled ones. In general, a silica-filled rubber compound contains silane coupling agent (bis-(3-(triethoxysilyl)-propyl)-tetrasulfide, TESPT) and diphenylguanidine (DPG) to improve the filler dispersion and to make fast cure characteristics. Acrylonitrile-butadiene rubber (NBR) improves the filler dispersion in silica-filled styrene-butadiene rubber (SBR) compounds. In this study, effect of NBR on the properties of silica-filled SBR compounds was investigated. Properties of the compounds which contain NBR without DPG or with small amount of TESPT (Compound A) were compared with those of the compounds which contain TESPT and DPG without NBR (Compound B). Scorch time of Compound A is faster than those of Compound B. Modulus and tensile strength of Comound A are slightly lower than those of Compound B. Traction property of the Comound A is better than that of the Compound B. Addition of NBR leads to reduction of the used amount of TESPT and DPG.

• Elastomers and Composites
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• v.44 no.2
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• pp.134-142
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• 2009

Organo bifunctional silane (TESPD) is added into silica containing NR and its effects are investigated with respect to the vulcanization properties, the processability, and the physical properties. The addition of the TESPD into silica filled NR compound increases the degree of crosslinking by formation of a strong 3-dimensional network structure with silica surface via coupling reaction, which results in an improved mechanical property. It also improves the processabilities compared to the Control compound.

• Elastomers and Composites
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• v.54 no.1
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• pp.54-60
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• 2019

The rapid development of the automobile industry is an important factor that led to the dramatic development of synthetic rubber. The tread part of tire that comes in direct contact with the road surface is related to the service life of the tire. Rubber compounds used in tire treads are often blended with SBR (styrene-butadiene rubber) and BR (butadiene rubber) to satisfy physical property requirements. However, when two or more kinds of rubber are blended, phase separation and silica dispersion problems may occur due to non-uniform mixing of the rubber. Therefore, in this study, we synthesized an SBR copolymer with the same composition as that of a typical SBR/BR blend compound by controlling butadiene content during ESBR (emulsion styrene-butadiene rubber) synthesis. Subsequently, silica filled compounds were manufactured using the synthesized ESBR, and their mechanical properties, dynamic viscoelasticity, and crosslinking density were compared with those of the SBR/BR blended compound. When the content of butadiene was increased in the silica filled compound, the cure rate accelerated due to an increased number of allylic positions, which typically exhibit higher reactivity. However, the T-2 compound with increased butadiene content by synthesis less likely to show an increase in crosslink density due to poor silica dispersion. In addition, the T-3 compound containing high cis BR content showed high crosslink density due to its monosulfide crosslinking structure. Because of the phase separation, SBR/BR blend compounds were easily broken and showed similar $M_{100%}$ and $M_{300%}$ values as those of other compounds despite their high crosslink density. However, the developed blend showed excellent abrasion resistance due to the high cis-1,4 butadiene content and low rolling resistance due to the high crosslink density.

• Elastomers and Composites
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• v.36 no.3
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• pp.162-168
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• 2001

Low molecular weight polybutadiene (liquid BR) improves the filler dispersion in a silica-filled styrene-butadiene rubber (SBR) compound. In the present work, influence of molecular weight or the liquid BR on properties of a silica-filled SBR compound was studied. Minimum and maximum torques in the rheocurve for the compound containing the liquid BR with higher molecular weight (HLBR) are lower than those for the compound containing the liquid BR with lower one (LLBR) while the delta torques are nearly the same. Mooney scorch time of the compound containing HLBR is faster than that of the compound containing LLBR. Modulus or the compound containing HLBR is lower than that of the compound containing LLBR while tensile strength of the former is higher than that of the latter. The elongation at break of the former is also longer than that of the latter. Stability for the thermal aging at $90^{\circ}C$ for 3 days is less favorable for the former than for the latter.

• Elastomers and Composites
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• v.47 no.1
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• pp.23-29
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• 2012

The silica-silica interaction parameter (${\alpha}_F$) of the silane treated silica filled natural rubber (NR) compound was investigated. As silane (TESPT) concentration increased from 2 to 12% (2, 4, 6, 8, 10, 12%), the ${\alpha}_F$ value increased at the same silica concentration (10, 20, 30, and 40 phr). It seemed the sulfur atoms in TESPT acted as a crosslinking agent in the compound. As silica concentration increased from 10 to 40 phr, the ${\alpha}_F$ value increased at the same silane concentration due to increased silica-silica interaction.

• Elastomers and Composites
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• v.33 no.4
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• pp.274-280
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• 1998

Order of reaction, rate constant, activation energy for vulcanization reaction, crosslinking density, and elastic constant of the network produced by sulfur curing were investigated on the SBR/BR blends containing silica and carbon black under same cure system. The reaction order was shown to be first order regardless of filler types. The carbon black filled rubber compounds showed higher rate constant compared to silica filled compounds. But activation energy appeared to be same regardless of filler type and rubber blend ratio. The crosslinking density and elastic constant is higher in the carbon black filled compound compared to silica filled compounds because of strong interaction between rubber and carbon black. On the other hand, crosslinking density and elastic constant were decreased with increasing the butadine rubber content in rubber blends. From the comparison of combined sulfur content in the vulcanized rubber, sulfur content in the silica filled compound become constant 20min later after reaction initiates but sulfur content in the carbon black filled compound become constant 10min later after reaction starts. The silica compound has a longer induction time ($t_2$) and optimum cure time($t_{90}$) compared to those of the carbon black filled compound.

• Macromolecular Research
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• v.8 no.6
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• pp.285-291
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• 2000

Influence of silane coupling agent, bis-(3-(triethoxisilyl)-propyl)-tetrassulfide, on cure characteristics and bound rubber content of filled styrene-butadiene rubber (SBR) compounds and on physical properties of the vulcanizates was studied. Carbon black-filled and silica-filled compounds were compared. Content of the bound rubber increased with increased content of the silane coupling agent and this trend was shown more clearly in the silica-filled compounds. Optimum cure time of the carbon black-filled compound increased with increase of the silane content, while that of the silica-filled one decreased. Cure rate of the carbon black-filled compound became slower as the silane content increased while that of the silica-filled one became faster. By increasing the silane content, the minimum torque decreased and the delta torque increased. Physical properties of the silica-filled vulcanizate were found to be improved by adding the silane coupling agent. However, for the carbon black-filled vulcanizates, the tensile strength and tear resistance decreased with increase of the silane content. The differences between the carbon black-filled and silica-filled compounds were explained by difference in the reactivities of the fillers with the silane.

• Polymer(Korea)
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• v.39 no.1
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• pp.107-113
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• 2015

The effects of silica-silane in CIIR vibration isolation compound were investigated regarding mechanical and dynamic properties. Addition of silica-silane in the compound resulted in higher tear resistance strength and elongation at break than the control, which was increased by 13% and 14%, respectively. Other values such as tensile strength and hardness did not show significant changes. Viscoelastic property results supported that the improvement of tear resistance strength and elongation at break resulted from the formation of 3-dimensional network structure between silica and CIIR. The mechanism of the tear resistance strength and elongation at break improvement was discussed.

• Elastomers and Composites
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• v.45 no.3
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• pp.223-229
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• 2010

We investigated the effects of processing geometry of silica-filled isobutylene-isoprene rubber (IIR) compounds on its mechanical properties and silica dispersion, using a two roll mill and an internal mixer (banbury mixer). The compound processed with the two roll mill showed the longer induction time ($t_2$), higher maximum torque ($T_{max}$), and better silica dispersion than the compound processed with the internal mixer; however, showed slightly the lower cure index ($t_{90}$). The mechanical properties (hardness, 300% modulus, tensile strength, elongation) of the compound processed with two roll mill were higher than compound done with the internal mixer.

• Elastomers and Composites
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• v.39 no.4
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• pp.263-273
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• 2004

The effects of zinc surfactant (ZB) on the bis(triethoxysilylpropyl)disulfide (TESPD)-silica mixture in natural rubber (NR) and solution butadiene-co-styrene rubber(S-SBR) were compared with respect to their rheological property, processability, physical properties, and silica dispersion. In the NR compound, addition of the ZB increased the reversion resistance time (T-2), the tensile modulus, and the BO time; however, lowered the viscosity, the HBU, and tans values. In the S-SBR copound, addition of the ZB increased the $tan{\delta}$ values while lowered the T-2, the tensile modulus the BO time, the viscosity, and the HBU of the compound. In the NR compounds, addition of the ZB significantly increased the processability and mechanical property. However, in the S-SBR compounds, it improved the processability the mechanical property was not improved.