• Applied Chemistry for Engineering
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• v.10 no.3
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• pp.419-426
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• 1999

In this study, the reaction rate constant, activation energy, total crosslinking density, elastic constant, cure properties ($t_5,\;t_{90}$), modulus, and abrasion resistance of rubber compounds were investigated as a function of cure temperatures, cure systems and reinforcing filler loadings. Reaction rate constants showed strong dependence on thc carbon black loading, cure temperature and cure system, and increased sharply with increasing the reaction temperatures. The lowest activation energy was obtained in the efficient cure (EC) system which corresponds to the high level of sulfur to accelerator ratio, and the activation energy was decreased with decreasing the carbon black loadings. The change of carbon black loadings directly affects the modulus and abrasion resistance, but the change of cure system showed various effects on the rubber compounds. Increased carbon black loadings showed the high modulus, improved abrasion resistance and short scorch time but decrease in crosslinking density and elastic constant. Higher crosslinking density and elastic constant were shown in the EC cure system regardless of carbon black loadings, but scorch timc ($t_5$) was not affected by the change of the ratio of sulfur to accelerator. Rapid optimum cure time ($t_{90}$) were showen in the EC cure system. Also, the equivalent cure curve coefficient of rubber compound was 0.96 for conventional cure (CC) system, and 0.94 for semi-efficient cure (SEC) and EC system regardless carbon black loadings. As regarding the abrasion resistance, wear volume showed the logarithmic increase for the loaded weight.

• Elastomers and Composites
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• v.22 no.1
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• pp.29-43
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• 1987

• Elastomers and Composites
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• v.21 no.4
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• pp.323-346
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• 1986

• Elastomers and Composites
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• v.33 no.5
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• pp.315-323
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• 1998

The purpose of this study was to investigate the crosslinking density and reinforcement of rubber compounds with various carbon black loadings, cure systems and cure temperatures. Bound rubber content increased with volume fraction of carbon black in rubber compounds, but total crosslinking density decreased with increasing the bound rubber content. Rate constant of cure reaction was changed significantly by cure system and cure temperature, especially it showed strong dependence on the cure temperature. High activation energys of cure reaction were shown in the rubber compound with high loading of carbon black under EC system and in the rubber compound with low loading of carbon black under CC system. High total crosslinking density of vulcanized compounds appeared in the rubber compound with low loading of carbon black and CC system among cure systems. Typical change of total crosslinking density by EC system was not shown. The highest elastic constant by Mooney-Rivlin equation was shown in the rubber compound with low loading of carbon black and SEC system. Modulus increased as increasing the loading of carbon black in the rubber compounds and showed the order of SEC, CC, and EC system for cure system.

• Elastomers and Composites
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• v.21 no.1
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• pp.13-19
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• 1986

The effects of several vulcanizing accelerators on the determination of kinetic parameters of natural rubber vulcanizate was studied by DSC. Kinetic parameters were determined by means of the calculation procedures of Borchardt-Daniels and Oscillating Disk Rheometer (ODR) cure curve analysis, using both DSC exothermal thermogram and ODR cure curve. In order to examine the credibility in the DSC method the same compound which was und for DSC method was used for the comparison with the results of ODR data. Upon this method, kinetic rate constant (k), and Arrehenius parameter (Ea, ko, n) have been determined for rubber compounds via a new method using DSC thermogram and ODR cure curve. In the comparison of DSC and ODR results, kinetic parameters has shown good agreements between two results. Consequently, from the present studies, it is shown that the DSC thermoanalytical method can provide an alternate new method of kinetic study of rubber vulcanization.

• Elastomers and Composites
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• v.13 no.3
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• pp.197-206
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• 1978

반응속도면(反應速度面)에서의 동력학적(動力學的) 연구결과(硏究結果)에 의(依)하면 2-메르캅토벤쪼티아졸(MBT)은 N-t-부틸-벤쪼티아졸썰펜아미드(BBTS) 또는 2-(4-몰폴리노티오) 벤쪼티아졸(OBTS)과 같은 가황촉진제(加黃促進劑)들 보다는 N-(싸이클로헥실티오)프탈이미드(CPT)가 훨신 더 빨리 반응(反應)한다는 사실(事實)을 탐지(探知)하였다. 또한 우수(優秀)한 가황지연제(加黃遲延劑)는 MBT와 급속(急速)히 반응(反應)하여야 하지마는 실소(室素)와 황(黃)과의 화학결합(化學結合)이 너무 약(弱)하여 내열안정성(耐熱安定性)이 없음으로 아무리 MBT와 빠른 속도(速度)로 반응(反應)하여도 좋은 가황(加黃)지연제가 될 수는 없다. 예를들면 N-(싸이클로헥실티오-O-벤쪼의 썰펜이미드(CTBS))는 CTP보다 더 빨리 MBT와 반응(反應)하지만 열안정성(熱安定性)이 부족(不足)하여 가황(加黃)지연제로서는 CTB 보다 좋지 못하다.

• 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.

• Journal of the Korean Chemical Society
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• v.15 no.6
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• pp.359-366
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• 1971

The extended Huckel calculations on five organic accelerators of vulcanization have been carried out. Various MO quantities e.g., electron populations and AO coefficients, are used to explain accelerator reactivity of the compounds. Results of these analyses lead us to support free radical mechanism of acceleration in vulcanization.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.4
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• pp.69-78
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• 2012

This paper study on the physical property of naturally vulcanizing waterproofing synthetic rubber sheet for the underground concrete wall. In order to finding the naturally vulcanizing time, the relation of vulcanizing time and tensile strength is analysed from non-vulcanizing to naturally vulcanizing time. Physical tests such as tensile strength, tear strength: etc., under the thermal environment temperature at $-20^{\circ}C$, $-10^{\circ}C$, $20^{\circ}C$, $60^{\circ}C$. The result of experiment show that the developed rubber sheet has the delay time about 85 days and the curing time about 35 days. The tensile strength increased by about 692% and coefficient of expansion decreased by about 10% which value can be sufficiently compensate the demerit of vulcanized rubber sheet. Also, all of the physical properties of the naturally rubber sheet satisfy the KS standard and compare to the vulcanized rubber sheet, the developed naturally rubber sheet have excellent durability.

• Korean Chemical Engineering Research
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• v.47 no.2
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• pp.169-173
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• 2009

Effects of variations sulfur/accelerator ratio on cross-linking and thermal degradation behavior of NR/CR rubber compounds were studied using both dynamic DSC and non-isothermal TGA. DSC thermograms of the given samples were obtained with several different heating rates, and after cross-liked in DSC, TGA thermograms with the same samples also obtained. Kissinger analysis was applied to assess the activation energies for the cross-linking and thermal decomposition processes. Results showed that the formation and thermal decomposition reaction of the samples occurred in the overall temperature range of $120{\sim}180^{\circ}C$ and $350{\sim}450^{\circ}C$, respectively, exhibiting that data could be well-fittable by Kissinger method. Furthermore, formation activation energy by DSC was estimated as $83.0{\pm}5.0kJ/mol$, which was much smaller than that of degradation by TGA, $147.0{\pm}2.0kJ/mol$. From these results, it was considered that, although variations of sulfur/accelerator ratio in the present experiments affected little on the formation mechanism and/or thermal degradation, they could play roles as the catalysts which lower the activation energy of formation. Because of stabilization after formation reaction, however, they have no more effects on the lowering the activation energy, showing higher values when decomposition, caused by main-chain scissions.