• 한국산업융합학회 논문집
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• 제2권1호
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• pp.97-103
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• 1999

The power curve during rubber mixing presents useful information for the understanding of rubber mixing process, because the power curve is determined the mixing state of rubber at the point. The time to the second peak on the power curve is known as carbon black incorporation time, BIT. This study gets the quantity relationship of BIT and viscosity of natural rubber, so by determining the mixing time of the compound on the ground of viscosity of the raw rubber. The mixing with natural rubber and carbon black is examined for various grade natural rubbers, encompassing a wide range of Mooney viscosity. Alter smoothing the mixing power curve using a polynomial, the carbon black incorporation time, BIT, was determined time to second power peak on the curve, The BIT's versus specific values on Mooney viscometer test curve show a linear relation, Especially, the peak of initial maximum torque on Mooney viscometer curve, PMT, is most relevant property relating to the BIT. PMT is useful index for determined optimum mixing time, To apply this results at the mixing, we effectively control the natural rubber mixing but can also know the grading of natural rubber upon processability.

• Macromolecular Research
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• 제8권4호
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• pp.192-198
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• 2000

Cure characteristics and physical properties of carbon black-filled natural rubber (NR) compounds depending on the mixing procedure were studied using the compounds with different pre-final mixing (FM-1) stages. Carbon master batch (MB) and first and second remitting (1RM and 2RM) stages were employed as the FM-1 stage. Bound rubber content of the FM compound decreased with increasing the mixing steps. This was due to the decrease of the molecular weight distribution of the polymer by the rubber chain scission during the mixing. The Mooney viscosity decreased with increasing the mixing steps. Cure characteristics of the compounds were found to be different with the mixing procedures. The cure times of the compound became slower by increasing the number of the mixing steps. This was explained by the length of rubber chain, the carbon black network, distribution of the curatives in the compound, and immobilization of the polymeric segments. Modulus and tensile strength of the vulcanizate did not show a specific trend with the mixing procedure. Fatigue life of the vulcanizate increased by increasing the mixing stages.

• Journal of the Korean Wood Science and Technology
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• 제26권1호
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• pp.70-75
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• 1998

In this paper, the relationships between volumetric mixing ratio of rubber chip and physical and mechanical properties of wood/rubber composite panel was examined in order to investigate the mixture characteristics of wood and rubber chip. Because of the specific gravity of rubber differed from wood chip, physical properties of wood/rubber composite panel was shown very different values by mixing rate of chip element. Specific gravity in air-dry of composite panel was increased rapidly as volumetric percent of rubber chip was increased. Moisture content of composite panel was decreased as volumetric percent of rubber chip element was increased. This results was considered that wood weight is light and porosity material for moisture absorption. Compressive strength and modulus of rupture in bending test were decreased as volumetric percent of rubber chip increased. By mixing ratio control of chip elements, various wood/rubber composite panel can be applicable to every interior materials such as subfloor, playground, and exterior materials such as road blocks for recreational facilities in garden and forest and city parks.

• Elastomers and Composites
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• 제37권1호
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• pp.14-20
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• 2002

실리카로 보강된 고무 배합물은 보강제의 분산이 나쁘기 때문에 카본 블랙으로 보강된 배합물에 비해 더 긴 배합 시간이 필요하다. 실리카와 카본 블랙으로 보강된 천연 고무 배합물에서 배합 공정이 물성에 미치는 영향을 연구하였다. 마스터뱃치(MB) 배합물의 최종 온도를 $150^{\circ}C$로 하였을 때, 실리카와 카본 블랙을 따로 투입하는 경우가 함께 투입하는 공정보다 배합 시간을 더 길게 가질 수 있었다. 실리카를 먼저 투입하는 것이 카본 블랙을 먼저 투입하는 것보다 배합 시간이 길었다. MB 배합 공정을 한 단계로 구성한 배합물과 두단계로 구성한 배합물을 비교하였다. 두 단계 공정으로 배합한 배합물의 스코치 시간이 한 단계 공정으로 만든 배합물의 스코치 시간보다 길었고 bound rubber 함량은 작았다. 두단계 공정으로 만든 가황물은 한단계 공정으로 만든 것에 비해 신율이 높고 인장 강도도 강하고 피로 특성도 우수한 것으로 나타났다.

• 한국환경과학회지
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• 제19권3호
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• pp.365-370
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• 2010

In this study, we carried out the evaluation of EPDM(Ethylene Propylene Diene Monomer) reclaimed rubber mixing with natural rubber at various mixing ratio to reuse as rubber filler. The scorch time and moony viscosity was analyzed to evaluate the effect of cure behavior. And also, we analyzed the tensile strength, the elongation at break and cure time to evaluate the variation of cure behavior. As the results, the scorch time and optimal cure time was decreased according to the increasing of EPDM reclaimed rubber. However, the moony viscosity was increased at each mixing ratio. In case of the added EPDM reclaimed rubber was 20 phr(parts by weight per 100 parts by weight of rubber), the hardness and specific gravity was increased a little. The hardness and specific gravity was increased in rapidly under 40 phr of the added EPEM reclaimed rubber. The tensile strength and elongation at break of the compound of natural and EPDM reclaimed rubber was rapidly decreased compared with its natural rubber when the ratio of adding EPDM reclaimed rubber was over 40 phr.

• Elastomers and Composites
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• 제48권2호
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• pp.103-113
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• 2013

실리카와 실란을 포함하는 고무 복합체의 최적 배합조건을 찾기 위하여 배합온도와 시간을 달리한 고무복합체의 특성을 평가하였다. 고무복합체의 제조를 위한 배합온도는 $120^{\circ}C$, $140^{\circ}C$, $160^{\circ}C$의 다양한 배합시간으로 배합한 후 고무복합체의 특성을 평가하였다. 배합시간이 증가할수록 점도의 감소와 결합고무가 증가하였으나, 배합시간의 증가에 따른 점도의 변화는 배합온도가 낮을수록 크고, 결합고무의 증가속도는 온도가 높을수록 크게 나타났다. 낮은 온도인 $120^{\circ}C$인 경우 배합 시간이 바뀌어도 가교 속도는 거의 일정한 반면 10분 이하의 배합 시간에서는 분산이나 반응이 충분치 않음을 동적 점탄성과 분산 평가 등을 통하여 알 수 있었다. 반대로 높은 온도에서는 충분한 반응에 의하여 동적 점탄성 특성 등이 우수한 것으로 나타나지만 가교 속도나 물성의 변화 등이 매우 민감하고 과도한 결합고무의 형성 때문에 적합한 온도 조건이 아님을 확인하였고, 변성 S-SBR 실리카 배합에서는 $140^{\circ}C$에서 10분 정도의 배합이 분산과 실리카-실란 결합의 최적 조건임을 확인하였다.

• Elastomers and Composites
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• 제51권2호
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• pp.81-92
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• 2016

1,3-Diphenylguanidine (DPG) is commonly used as a secondary accelerator which not only acts as booster of cure but also activating silanization reaction. The aim of this study is to increase the interaction between silica and rubber by using DPG. In this study, mixing was proceeded in two steps. The T-1 compound is mixed DPG with silica and silane coupling agent in the kneader at high temperature which is named as $1^{st}$ mixing step. T-3 compound is mixed DPG with curatives in the two-roll mill at low temperature which is named as $2^{nd}$ mixing step. The T-2 compound is mixed a half of DPG in $1^{st}$ mixing step and the remainder is mixed in $2^{nd}$ mixing step. Total DPG content was equal for all compounds. When DPG is mixed with silica, silane coupling agent during the $1^{st}$ mixing step, a decrease in cure rate and an increase in scorch time can be seen. This indicates that DPG is adsorbed on the surface of silica. during rubber processing. However, bound rubber content is increased and dynamic properties are improved. These results are due to the highly accelerated silanization reaction. However, there are no significant difference in 100%, 300% modulus.

• Macromolecular Research
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• 제9권1호
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• pp.37-44
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• 2001

A premixing effect for the properties of carbon black-filled rubber compounds was investigated using biblends of natural rubber (NR), styrene-butadiene rubber (SBR), and butadiene rubber (BR). Degree of mixing of the biblends was controlled by preblending time of 0.0, 2.5, and 5.0 min. Mooney viscosities of the compounds decreased by increasing the preblending time. Of three carbon black-filled compounds of NR/SBR, NR/BR, and SBR/BR compounds, only the SBR/BR blends showed a specific cure characteristics depending on the preblending time. For the bound rubber composition, the NR content was higher than SBR and BR. The difference in the rubber composition ratio of the bound rubber became smaller with increasing the preblending time. Physical properties of the vulcanizates such as hardness, modulus, tensile property, abrasion loss, and tans were also compared. Differences in properties of the compounds were discussed with miscibility of the dissimilar rubbers and degree of mixing.

• Macromolecular Research
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• 제13권1호
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• pp.30-38
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• 2005

Sulfur-cured gum natural rubber vulcanizates were devulcanized using two different concentrations of diallyl disulfide. The devulcanization process was performed at $110^{\circ}C$ min in an open two-roll cracker-cum-mixing mill. Natural rubber vulcanizates having various sulfur/accelerator ratios were used to study the cleavage of monosulfide, disulfide, and polysulfide bonds. The properties of devulcanized natural rubber increased upon increasing the disulfide concentration and the mechanical properties of the revulcanized natural rubber increased upon decreasing the sulfur content in the original rubber vulcanizates. The scorch time and the maximum state of cure both increased when the ground vulcanizates were treated with higher amounts of disulfide. TGA and DMA were conducted to study the effects of the devulcanization on the thermal stability and the $T_g$ behavior of the vulcanizates. SEM analysis was conducted to study how the failure mechanism was affected by the devulcanization process. It was possible to recover $70-80\%$ of the original gum rubber properties by using this process. From IR spectroscopic analysis, we observed that the oxidation of the main chains did not occur during high-temperature milling.

• Elastomers and Composites
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• 제26권4호
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• pp.287-295
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• 1991

The mixing process with carbon black is important in the rubber industries. However, it is difficult to characterize the mixing mechanism of the carbon black. The mixing mechanism(distributive mixing and dispersive mixing) was discribed in this paper. The effect of fill factor on the mixing of the carbon black was studied. The dispersive mixing ability increases with increasing fill factor. However, the distributive mixing ability decreases with increasing fill factor. The effect of the carbon black content on the rheological property of the material was studied in this paper. The viscosity of the material increases with increasing the carbon black content. However, the elasticity of the matarial decreases with the carbon black content.