• Elastomers and Composites
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• 제53권3호
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• pp.150-157
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• 2018

Fatigue properties of rubber are one of the most important characteristics in the rubber industry. In this study, the fatigue properties of MREs (magneto-rheological elastomers) based on NR (natural rubber), EPDM (ethylene-propylene diene monomer), and AEM (ethylene/acrylic elastomer) were investigated. For comparison, MREs with a Shore hardness of 60A were prepared. According to the relative results, the fatigue properties of EPDM MRE were the worst. Thus, we investigated methods to improve the fatigue properties of EPDM MRE by varying the carbon black content and curing systems of EPDM as the matrix of the MRE. Dynamic properties were measured using a fatigue tester and an RPA (rubber process analyzer), and the XPS (X-ray photoelectron spectroscopy) was used to analyze the curing system of the EPDM matrix. According to the results, the Payne effect increased and the fatigue resistance decreased as the carbon black content increased. In case of the curing system, the CV (conventional vulcanization) system was superior to the EV (efficient vulcanization) system in terms of the fatigue resistance. This was because the number of flexible bonds in the case of the CV system was higher than that in the case of the EV system. However, the EV system showed excellent mechanical properties because it had many monosulfidic bonds with strong binding energy.

• Elastomers and Composites
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• 제55권3호
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• pp.184-190
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• 2020

In the wet master batch process, process oil is used to improve the workability of silica-SBR. The process oil expands the polymer and provides lubrication to soften the stiff rubber chain. However, addition of excess process oil can interfere in the crosslinking reaction between rubber molecules and reduce the crosslinking density of silica-SBR. Controlling the amount of process oil is an important aspect for properly controlling the workability and crosslinking density of silica-SBR. In this study, silica-SBR was prepared by adjusting the amount of process oil to confirm its effect on silicaSBR. Vulcanization characteristics of silica-SBR were examined using a moving die rheometer. Dynamic viscoelasticity was measured using a dynamic mechanical thermal analyzer, and the mechanical properties were investigated using the universal testing machine according to ASTM D412. As a result, all silica-SBR compounds with 10 to 40 phr of process oil have effects of improving the processability and the silica dispersibility. Also, the optimum condition was determined when 10 phr of processed oil was added because the abrasion resistance was improved 65% compared to that at 40 phr.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.632-635
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• 2007

Automobile tire has very complicated shape and is composed of rubber, steel cord and ply cord, Tread pattern of tire is very essential for the basic characteristics of tire, such as braking, acceleration and comfortableness. Tire components such as tread, sidewall, and spex are prepared by forcing uncured rubber compound through an extruder to shape during curing process. Because of its complexity of shape, adaptive mesh refinement was used for the analysis of tire tread. Effects of forming variables were evaluated.

• Elastomers and Composites
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• 제33권2호
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• pp.103-109
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• 1998

The determination method of successful operation conditions to control the temperature and pressure in autoclave after non-taping vulcanization process was represented. Heat and mass balances were constructed to predict the mass flow rates of air, steam, and condensed water into or from autoclave when the temperature and pressure in the autoclave were to be controlled in the desired profiles. The balance equations were solved by appropriate mathematics, and the solution was applied to an autoclave system where the temperature and pressure were linearly decreased. The resulting solutions were illustrated in graphs.

• 한국산업융합학회 논문집
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• 제2권1호
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• pp.69-75
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• 1999

Intending to develop a new rubber curing process using only microwave, the both the characteristics of cure and the mechanical properties of rubbers for the tire tread, for which a green styrene-butadiene compounds had been cured with 2.45 GHz microwave, have been compared with those of the custom thermal cured rubber. The unintentional hot spot formation in the compound during the microwave curing has not found where the compound has a microwave absorbing ceramic powders in 4.18 weight percents and the supplying voltage has been adjusted to 90 volts. The new microwave process accomplished preheating to 418K in a quarter of the thermal cure time. The average tensile strength of the microwave-cured rubber indicating $190kg/cm^3$ was compatible to that of the thermal cure. In conclusion, the new microwave cure had approved to be applicable in a commercial plant.

• Macromolecular Research
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• 제10권6호
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• pp.345-358
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• 2002

The electrical conductivity during vulcanization process was measured as a function of time for the system of TiC loaded styrene-butadiene rubber (SBR) composites. The phenomenon of negative and positive temperature coefficients of conductivity and its conduction mechanism were also studied for the SBR polymeric composites. The current-voltage characteristics of the polymeric composites were non-linear in high voltage and showed a switching effect. The effects of temperature on the thermal conductivity and effective dielectric constant were measured. The measured parameters were found to be dependent on TiC concentration. The electromagnetic wave shielding (EMS) of the SBR-TiC polymeric composite was also examined. The SBR filled with TiC could be expected to be promising novel smart polymeric composites for self-electrical heating, temperature sensor, time delay switching, and electro-magnetic wave shielding effectiveness.

• 폴리머
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• 제34권3호
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• pp.215-219
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• 2010

충전제로서 Cloisite$^{(R)}$ 10A와 carbon black을 사용하여 NBR 복합체를 제조하였다. 충전제로서 Cloisite$^{(R)}$ 10A를 사용했을 경우 복합재료의 기계적 물성, 내유성, 그리고 산소 투과성 등이 carbon black을 사용했을 경우 보다 우수하였다. 특히, 복합재료의 경화에 있어서 Cloisite$^{(R)}$ 10A를 사용하였을 경우 scorch 시간과 경화시간이 단축됨을 확인할 수 있었다. 이러한 결과로부터 Cloisite$^{(R)}$ 10A에 삽입되어 있는 알킬 암모늄 이온이 복합재료에 있어 가황 촉진제의 역할을 하고 있음을 알았다.

• Elastomers and Composites
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• 제32권3호
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• pp.157-165
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• 1997

The morphology of the thermoplastic vulcanizates prepared from ethylene-propylene-diene terpolymer, polypropylene and high density polyethylene(HDPE) or ethylene based ionomer were studied. Blends were prepared in a laboratory internal mixer where EPDM was cured in the presence of PP and HDPE or ionomer under shear with dicumyl peroxide(DCP). The effects of DCP concentration and rubber/plastics composition were studied. In the morphological analysis by scanning electron microscopy (SEM), a small amount of EPDM acted as a compatibilizer to HDPE and PP. It was also revealed that the dynamic vulcanization process could reduce the domain size of the crosslinked EPDM phase. When ionomer was added to EPDM/PP blend, the thermoplastic vulcanizate showed typical ductile fracture topology and the trend was more clearly observed when DCP contents and ionomer contents are higher.

• 폴리머
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• 제27권5호
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• pp.436-442
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• 2003

에틸렌-프로필렌 디엔 고무 (EPDM)와 같은 열경화성 탄성체는 자동차의 스폰지 웨더스트립 (sponge weatherstrip)에 적용되는 주 재료이다. 그러나 열경화성 탄성체의 특성 때문에 환경적인 문제가 야기된다. 더구나 EPDM 재료의 weatherstrip 제조 시 배합, 가류와 같은 여러 생산 공정을 거쳐야 함으로 생산 단계별 품질산포가 크고 제품의 형상 유지가 어려워 품질의 안정성이 떨어진다. 따라서 재활용과 획기적인 제조기술 그리고 수발포를 할 수 있는 새로운 열가소성 가황체 (TPV)재료 개발로 종래의 EPDM 웨드스트립 제조 문제들을 개선이 필요하게 되었다. 본 연구에서는 TPV 수발포 공정에서의 발포체의 밀도와 구조적인 면을 물의 양과 발포 온도 등의 가공 조건들의 영향을 수행하여 TPV가 수발포로서 균일한 발포체를 얻을 수 있다는 것을 알 수 있었다. 연구결과 EPDM 웨더스트립의 많은 재활용이 곤란한 문제점 등을 해결할 수 있고, 이 새로운 발포 기술은 고무산업에 돌파구를 만들어 나갈 것으로 기대된다.

• 한국기계가공학회지
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• 제21권8호
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• pp.79-86
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• 2022

With the recent increase in the demand for electric vehicles, it is necessary to identify the high current safety of automobile parts. Among the automobile parts, the EPDM parts required colored parts from the existing black; therefore, it was necessary to change the basic filler from carbon black to silica. The rubber used in automobile parts is flexible and exhibits basic characteristics of high strength and elongation. However, as the filler is changed to silica, its physical properties, such as tensile strength and elongation, are lower than those of the existing carbon black base. Therefore, it is necessary to evaluate the mechanical properties with the addition of the EPDM compound using silica as a base without degrading the physical properties of EPDM. In this study, an experiment based on the additive content was performed using the mixture experimental planning method to analyze the mechanical properties according to the additive type and mixing ratio of silica-based EPDM. The mixing ratio of the four additives was set using a simplex lattice design, and the tensile strength, elongation, modulus 300%, and permanent compression reduction rate were analyzed for mechanical characteristics, and rheometer experiments were performed for vulcanization characteristics. Through statistical analysis of the measured data, the main effects and interactions of the EPDM-blended rubber additives were analyzed. These results can be used to derive a mixing ratio of additives that satisfies the required characteristics of the EPDM compound.