• Elastomers and Composites
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• v.41 no.3
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• pp.164-171
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• 2006

Stress softening behaviors of SBR vulcanizates reinforced with silica or carbon black were studied. Two types of SBR with different 1,2-unit contents of 18 and 60 wt% were used and three filler systems of carbon black and silica with/without silane coupling agent were employed. Stress softening behaviors of the SBR vulcanizates were varied with the SBR types as well as the filler systems. The silica-filled rubber specimens had higher residual strains than the carbon black-filled ones. The residual strains of silica-filled vulcanizates were remarkably reduced by adding a silane coupling agent. The maximum loads at 50% maximum stretch of the carbon black-filled vulcanizates were lower than those of the silica-filled ones. On the contrary, the maximum loads at 200% maximum stretch of the carbon black-filled vulcanizates were higher than those of the silica-filled ones. The maximum loads of the specimens with the 1,2-unit content of 60 wt% are higher than those with the 1,2-unit content of 18 wt% irrespective of the filler systems.

• Elastomers and Composites
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• v.19 no.4
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• pp.231-242
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• 1984

NR vulcanizate has its unigue characteristic of cushion, silence, vibration energy absorbtion etc. By reason of the above captioned characters, The vulcanizate has been widely applied to production of auto tires, belts and engine mounts, The purpose of this study is to examine the effect of rubber-filler attachments on the various dynamic properties of the NR vulcanizates. For this study, the elastic modulus and damping values are examined by means of the (RDS) the Good Rich Flexometer. The results of this study showed as follows. The damping values of the vulcaniz ates in the elastic region showed showed strong relations the damping values and the filler characteristics. The vulvanizates filled with carbon black had higher damping values than the vulcanizates loaded with inorganic filler. The Goodrich Flexometer test showed that build up for the silica filled NR vulcanizates was higher than those for which contained other fillers.

• Elastomers and Composites
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• v.35 no.4
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• pp.261-271
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• 2000

Physical properties of NR vulcanizates cured by both sulfur and resole were studied. Cure characteristics of the compounds were also investigated. Two types of resoles with different molecular weight distributions were employed. The scorch time of the NR compound containing the resole with a low molecular weight distribution was shorter than that of the compound containing the resole with a high one. Crosslink densities of the NR vulcanizates with a high resole content after the thermal aging at $95^{\circ}C$ decreased, while that of the vulcanizate without resole after the thermal aging at $95^{\circ}C$ increased. Though crosslink densities of the NR vulcanizates with a high resole content decreased with increasing the aging time, the moduli increased while the tensile strength and tear strength decreased.

• Elastomers and Composites
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• v.29 no.1
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• pp.18-29
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• 1994

The purpose of this study is to investigate reinforced effect between silica treated by coupling agents and rubber matrix under the configuration chemical bonds, and the effect of silica particles coated by organic polymers using aluminum chloride as the catalyst. In vulcanization characteristies were tested by Curastometer. The M-series vulcanizates were reached to the fastest optimum cure $time(t_{90})$ and R-series vulcanizates with the same formula had the shorted optimum cure times. Tensile characteristics measuring with a tensile tester revealed that the M-series vulcanizate was the best in the physical properties, such as tensile strength. In 100% modulus, however, the S-series vulcanizates appeared to be better than the other vulcanizates. Also, hardness showed the following order : S-series>R-series>M-series with the order of elongation R-series>M-series>S-series. In SEM test, shapes of chemical treated silicas were observed. The dispersion of filler in the SBR composite appeard uniformly. In RDS test for the dynamic characteristics, G' indicates that S-3 shows the highest value with the next order M-3>R-3, and the order of damping values are as followe: M-3>M-3>R-3.

• Elastomers and Composites
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• v.40 no.4
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• pp.237-241
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• 2005

Influence of the styrene content on the retraction behaviors of SBR vulcanizates was studied. SBRs with different styrene contents of 15 and 21 wt% were used. The vulcanizate with low styrene content started to recover at lower temperature than that with high one. The recovery rate of the vulcanizate with low styrene content was slower than that with high one. The recovery difference between the two vulcanizates with different styrene contents was larger for the carbon black-filled vulcanizates than for the silica-filled ones. The experimental results were explained with the glass transition temperature and modulus.

• Journal of Adhesion and Interface
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• v.3 no.2
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• pp.30-39
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• 2002

The effect of cure accelerator content on the change in crosslink density by thermal aging was studied for silica-filled natural rubber (NR) vulcanizates. Influence of silane coupling agent was also investigated. N-tert-Butyl-2-benzothiazole sulfenamide (TBBS) and bis-(3-(triethoxysilyl)-propyl)-tetrasulfide (TESPT) were used as a cure accelerator and a silane coupling agent, respectively. The crosslink density increased by thermal aging and the increasing level became larger as the aging temperature increased. The degree of crosslink density change of the vulcanizates without the silane coupling agent was larger than that of the vulcanizates containing the silane coupling agent. For the vulcanizates silane coupling agent, the activation energy for the crosslink density change decreased with increase of the cure accelerator content in the vulvanizate.

• Elastomers and Composites
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• v.34 no.4
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• pp.341-349
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• 1999

In this study, heat and crack resistance of natural rubber (NR) compounds was evaluated. To prevent the effects of the crosslinking system, a conventional vulcanization system was selected, where the accelerator/sulfur ratio was fixed to 0.25. Vulcanizates containing phenylenediamine showed high tensile strength and tear strength compared to other vulcanizates because phenylenediamine can cause additional crosslinking and high dispersion In the vulcanizates. In the pure shear test, vulcanizates containing phenylenediamine showed an excellent tearing energy which was due to the irregular crack path, and showed excellent heat and crack resistance which was also due to the good dispersity of antioxidant and additional crosslinks in the rubbber vulcanizates.

• Elastomers and Composites
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• v.40 no.3
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• pp.181-187
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• 2005

Changes of physical properties or NR vulcanizates with different cure systems by thermal aging were investigated. Two sulfur cure systems and one resole cure system were employed, and total contents of the curatives were varied. For the NR vulcanizates with sulfur cure systems, hardness and modulus after the thermal aging at $90^{\circ}C$ for 3 days were increased, but elongation at break and tensile strength were decreased. For the NR vulcanizates with resloe cure system, the physical properties after the thermal aging were decreased. The change of physical properties by the thermal aging was explained with the crosslink density change. The crosslink densities or the NR vulcanizates with sulfur cure systems were increased after the thermal aging, but those with resole cure system were decreased. Influence of the migration of antidegradant on the changes of physical properties was also investigated. However, the changes of physical properties by the thermal aging were not explained sufficiently with the migration of antigradant.

• Elastomers and Composites
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• v.22 no.3
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• pp.204-212
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• 1987

The purpose of this study is to investigate the reinforced effect between MGF treated silane coupling agents and rubber matrix under the configuration chemical bonds, also the effect of triazine thiol compounds. For this study, vulcanizates were prepared with fifteen different compounding formulas. Their vulcanization characteristics, physical properties were examined by means of the ODR(Oscillating Dist Rheometer), the tensile tester, the benzene swelling test. The results of this study obtained are as follows: 1. In the ODR test, the MA vulcanizate was the fastest one in terms of having reached to optimum cure time($t_{90}$) and, with the same formula, when MGF vulcanizates, the shortest optimum cure times has appeared. 2. The SA, SC vulcanizates were the best the other in the physical properties such as 100%modulus, 200%modulus, 300%modulus, tensile strength. The SB vulcanizate, with higher density of crosslinking than other vulcanizates. The vulcanizates, which were filled with MGF treated with silane coupling agents we were the higher density of crosslinking than vulcanizates filled with MGF only. 3. In aging properties, the silica vulcanizates appeared to be better than the other vulcanizates. The aging Properties of treated MGF vulcanizates were similar to the silica vulcanizates. The(CR+APS+silica) and(CR+APS+MCF) were easily crosslinked by exposure to the air, and the physical properties have been improved.

• Elastomers and Composites
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• v.22 no.4
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• pp.314-323
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• 1987

A blend ratio of rubber vulcanzates comprising NBR, CR, EPDM, NR, BR, and SBR alone or blended is determind through a P.G.C. It is found that a characteristic peak of elastomer is proportional to the content of each elastomer when they are pyrolysed. It is also classified to the different AN content in NBR vulcanizates, identification of sulfur-modified and non-sulfur bearing CR polymers, and the content of ethylene, propylene monomer and the third monomer in EPDM vulcanizetes.