• Elastomers and Composites
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• 제55권1호
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• pp.59-66
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• 2020

Herein, we investigated the thermal conductivity and thermal stability of natural rubber composite systems containing hybrid fillers of boron nitride (BN) and aluminum nitride (AlN). In the hybrid system, the bimodal distribution of polygonal AlN and planar BN particles provided excellent filler-packing efficiency and desired energy path for phonon transfer, resulting in high thermal conductivity of 1.29 W/mK, which could not be achieved by single filler composites. Further, polyethylene glycol (PEG) was compounded with a commonly used naphthenic oil, which substantially increased thermal conductivity to 3.51 W/mK with an excellent thermal stability due to facilitated energy transfer across the filler-filler interface. The resulting PEG-incorporated hybrid composite showed a high thermal degradation temperature (T₂) of 290℃, a low coefficient of thermal expansion of 26.4 ppm/℃, and a low thermal distortion parameter of 7.53 m/K, which is well over the naphthenic oil compound. Finally, using the Fourier's law of conduction, we suggested a modeling methodology to evaluate the cooling performance in thermal management system.

• Elastomers and Composites
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• 제35권4호
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• pp.303-310
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• 2000

Low temperature retraction characteristics were investigated on the cured natural rubber with various ratios of crosslinking agents, filler and additives. The cured natural rubber product was elongated about 200% at $-40^{\circ}C$ for 24 hours and then retracted. In a definite range, the retraction was increased as the sulfur to accelerator ratio increased and as the filler contents decreased. The retraction was maximum for a definite range of amount of accelerators, plasticizer and activator. Adding some peroxide additively retraction characteristics improved and curing time got longer.

• Elastomers and Composites
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• 제33권3호
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• pp.201-209
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• 1998

Alumina powders used as a filler in rubber compounding was extracted from kaolin in $H_2SO_4$ solution employing conventional thermal and microwave energy resources. Maximum degrees of alumina extraction from kaolin were 72.8% at $80^{\circ}C$, 1M $H_2SO_4$, and 180min in the conventional thermal extraction process and were 99.0% at $90^{\circ}C$, 1M $H_2SO_4$,, and 60min in the microwave extraction one, respectively. The samples synthesized in both processes were analyzed by means of TG/DTA, XRD, SEM, Atomic Emission Spectroscopy, and BET method. Studies are presently under way to unravel the basic interaction mechanisms between microwave and alumina power for high rates of alumina extraction from kaolin in the microwave ex-traction process.

• Elastomers and Composites
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• 제42권4호
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• pp.201-208
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• 2007

In this study, the thermal shrinkage and expansion stresses of filled NR and SBR vulcanizates were measured to investigate the dimensional stability at an elevated temperature. When a rubber sample was held at constant pre-strain, a thermal stress developed upon heating due to the entropic consideration. The peak shrinkage stress of carbon black or silica filled NR decreased with increasing filler content. In SBR compounds, however, the peak shrinkage stress of SBR with 30 phr filler content was higher than that of unfilled compounds. The expansion stress of carbon black filled NR was changed little, but that of filled SBR increased with increasing the filler content. The peak expansion stress of silica filled NR and SBR vulcanizates increased with increasing silica content.

• Elastomers and Composites
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• 제33권2호
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• pp.75-82
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• 1998

The purpose of this experimental study was to investigate the effects of vulcanization condition on the properties of reinforced rubbers. Rubber reinforcing ability of carbon black was more efficient than other fillers, but tensile properties were not affected by vulcanization condition while vulcanization condition affected the physical properties of rubber compounds with silica and silane treated slica. It was found that silica and silane treated silica filled rubber compounds showed good dynamic properties, rebound, heat build-up, 0 and $60^{\circ}C$ tan $\delta$ compared with carbon black filled rubber compounds. Carbon black filled rubber compounds were higher than silica and silane treated silica filled rubber compounds in total crosslinking density by vulcanization condition. By analysis of crosslinking type, polysulfide crosslinking was the highest in the carbon black filled rubber compounds with decreasing the ratio of sulfur to accelerator, monosulfide crosslinking was the highest in the silane treated silica filled compounds with in-creasing the ratio of sulfur to accelerator.

• Elastomers and Composites
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• 제33권4호
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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.

• Elastomers and Composites
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• 제33권1호
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• pp.44-51
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• 1998

The purpose of this experiments were investigated on the physical properties of rubber com-pounds containing two types carbon black. Bound rubber and interaction coefficient for com-pounds with pure carbon black were higher than those for the compounds with dual phase carbon black. Slightly higher values in 300% modulus and tensile strength indicated that the ratio of rubber-filler bound to rubber-rubber bound of pure carbon black were higher than those of com-pounds with dual phase carbon black. It was founded that dynamic properties, that is rebound, heat build-up, 0 & $60^{\circ}C$ tan $\delta$, and cut and chip loss of compounds with dual phase carbon black were better than those of compounds with pure carbon black, but abrasion property of dual phase carbon black was lower than those of pure carbon black because of low reinforcing ability.

• Elastomers and Composites
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• 제55권3호
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• pp.161-166
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• 2020

On the basis of the use of shoes, the outsole, which is mainly made of rubber, has various characteristics. The most important of these characteristics is abrasion resistance and friction. Generally, the abrasion resistance can be improved by adding more reinforcing filler such as silica to the rubber; however, the friction force drops. Owing to these problems, rubber having excellent abrasion resistance and rubber having excellent frictional force are blended. In this study, various characteristics, including wear resistance and friction, were evaluated by blending NBR/SBR or NBR/BR mixture with high wear resistance and CIIR with high friction. The CIIR was increased up to 60 phr, whereas the friction wear characteristics were rapidly changed in the NBR/CIIR blend ratio from 75:15 to 60:30.

• Elastomers and Composites
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• 제41권3호
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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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• 제52권2호
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• pp.114-130
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• 2017

Enhancing the properties of rubber, such as the tensile strength, modulus, and wear abrasion, by the addition of carbon black and silica as fillers is very important for improving the performance of rubber products. In this review, we summarize the general features of 'the reinforcement of rubber by fillers' and the equations for representing the reinforcement phenomena. The rubber reinforcement was attributed to enhancement of the following: the rubber, bound rubber, formation of networks, and combination between rubber chains and silica followed by entanglement. The reinforcement capability of silica species with different surface and networked states demonstrated the importance of the connection between the silica particles and the rubber chains in achieving high reinforcement. The model involving combination followed by entanglement can provide a plausible explanation of the reinforcement of rubber by carbon black and silica because the combination facilitates the concentration of rubber chains near the filler particles, and entanglement of the rubber chains around the filler particles enforces the resistance against deformation and breakage of rubber compounds, resulting in high reinforcement.