• 대한기계학회논문집A
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• 제25권11호
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• pp.1887-1894
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• 2001

The effects of carbon black on the material properties and the fatigue life of the carbon-black filled natural rubbers were investigated. Different kinds of carbon blacks resulted in different fatigue lives, hysteresis, and critical J-values. It was noticed that the hysteresis was inversely proportional to the difference between DBPA and CTAB, and the critical J-value was almost the same regardless of the length of a precrack. In addition, different kinds of carbon blacks resulted in different fracture morphologies, and micro-scale and macro-scale roughnesses. The critical J-value was proportional to the micro-scale roughness. and it seemed relate to the size distribution of carbon black particles. By reviewing all the experimental data. it was finally noticed that the logarithmic value of the fatigue life could be linearly expressed by a multiplication of the critical J-value and the logarithmic value of the hysteresis.

• Structural Engineering and Mechanics
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• 제61권5호
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• pp.645-655
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• 2017

To determine the seismic applicability of a long-span railway concrete upper-deck arch bridge with concrete-filled steel-tube (CFST) rigid skeleton ribs, some fundamental principles and seismic approaches for long-span bridges are investigated to update the design methods in the current Code for Seismic Design of Railway Engineering of China. Ductile and mixed isolation design are investigated respectively to compare the structural seismic performances. The flexural moment and plastic rotation demands and capacities are quantified to assess the seismic status of the ductile components. A kind of triple friction pendulum (TFP) system and lead-plug rubber bearing are applied simultaneously to regularize the structural seismic demands. The numerical analysis shows that the current ductile layout with continuous rigid frame approaching spans should be strengthened to satisfy the demands of rare earthquakes. However, the mixed isolation design embodies excellent seismic performances for the continuous girder approaching span of this railway arch bridge.

• Elastomers and Composites
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• 제38권1호
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• pp.81-87
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• 2003

본 연구에서는 $FeCl_2{\cdot}4H_2O,\;(CH_2)_6N_4$ (hexamethylene tetramine) 그리고 $NaNO_2$로부터 $Fe_3O_4$ (magnetite)를 제조하고 결정성 CR고무에 배합하여 전도성 충전제의 함량이 물성에 미치는 효과와 전기전도도 (${\sigma}$)의 온도 의존성을 조사하였다. 최소 최적 혼합비(percolation threshold, $P_c$) 개념이 본 연구에서 제조한 전도성 입자가 충전된 복합체에 적용되며, 혼합물내 $Fe_3O_4$의 분율이 27%를 초과할 때 전기전도도가 급격히 증가함을 확인하였다. 전기전도도의 온도 의존성은 $P_c$ 또는 그 이하에서 열적으로 활성화되며 magnetite가 CR 고무의 강화 및 전도성 충전제로서의 역할을 할 수 있음을 조사하였다. 또한, 50 phr의 magnetite가 충전된 복합체가 최적의 물리적 가교점으로 인하여 가장 우수한 인장강도와 파단시 신장율을 보였으며 모듈러스가 magnetite 의 강화효과 및 블랜드물의 가황 토오크 곡선으로부터 얻은 점도와 관련이 있음을 확인하였다.

• Elastomers and Composites
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• 제41권3호
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• pp.194-204
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• 2006

본 연구에서는 카본블랙 충전제의 입자크기 및 구조에 따른 고무 배합물의 마찰 마모 특성을 고찰하였다. 카본블랙의 입자크기와 구조에 따라 마모속도 및 형상이 다르게 되며, 최적 마모성능을 설계하기 위해서는 충전제의 입자크기와 구조의 마모 영향도를 사용조건에 따라 고려하여야 한다. 충전제의 입자크기와 구조에 따른 마모속도($W_R$) 영향도를 수준별로 고찰하기 위해 본 연구에서는 구조와 입자크기가 다른 10가지의 카본블랙을 선택하여 동일한 양을 천연고무와 배합하였다. 자체 제작한 칼날형 마찰 마모 시험기를 이용하여 마찰 마모 특성을 평가하였고, 카본블랙의 입자크기와 구조의 영향을 고려한 특성인자(${\psi}=\sqrt{{N_2^2}+{DBP^2}}$)와의 관계를 고찰하였다. 마모속도($W_R$)와 마찰일($W_f$)의 간에는 power-law 관계가 있었으며, 마모속도는 카본블랙의 특성인자에 역비례 관계를 보였다. 이는 카본블랙의 입자 크기가 작고 구조가 잘 발달 될수록 마모 저항특성은 향상된다는 것을 나타낸다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.259-259
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• 2009

Surface contamination and leakage current have caused operating problems. A flashover in a substation may result in destruction of an insulator or many others electrical equipment. Engineering plastics have good characteristic (light weight, good productivity and little of void) as compare with epoxy or porcelain insulators. Outdoor insulator must have resistance to contamination. However, they are not suited to outdoor insulator by reason of being not good hydrophobic. RTV has a good property of hydrophobic and ATH has characteristic obstructing exothermic reaction. In order to reduce the incidence of insulator flashover and damage, the silicon rubber contained nano size ATH coat on surface of engineering plastics. In this paper, it compares resistance tracking of the engineering plastic coated RTV with that of non-coated engineering plastic and ATH filled composites performed much better than non-filled composites.

• Elastomers and Composites
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• 제31권5호
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• pp.335-340
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• 1996

In order to look into the internal structure and the properties in the silicone rubbers added reinforcing fillers; silica $additives(O{\sim}140phr)$, and to examine the behavior of charged particles, the properties of thermally stimulated current(TSC) and X-Ray diffraction are investigated, respectively. And then, from the TSC which are formed by applying the electric field of $2{\sim}5kV/mm$ to specimen at the temperature range from -150 to $260^{\circ}C$, the results are as follwing: In the case of non-filled specimen, four peaks of ${\delta},\;{\gamma},\;{\beta}\;and\;{\alpha}$ are obtained at the temperature of $-120^{\circ}C,\;-60^{\circ}C,\;20^{\circ}C\;and\;130^{\circ}C$, respectively and the case of filled specimen, three peaks of ${\delta},\;{\alpha}_2\;and\;{\alpha}_1$ are observed at the temperature of $-120^{\circ}C,\;80^{\circ}C\;and\;130^{\circ}C$, respectively. The origins of these peaks are that, the ${\delta}$ peak seems to the result from the contribution of side chain methyl radical, and the ${\gamma}$ peak from the depolarization of space charge polarization owing to be added impurity during manufacturing specimens, and the ${\beta}$ peak from the orientation of $Si-CH_3$ dipole, and the ${\alpha}_2$ near the temperature of $80^{\circ}C$ from hydroxyl in carboxylic radical, and finally, the ${\alpha}_1$ peak near the temperature of $130^{\circ}C$ from carboxyl acid that is formed by the thermal oxidation of high temperature.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술대회 논문집
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• pp.29-29
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• 2010

Surface contamination and leakage current have caused operating problems. A flashover in a substation may result in destruction of an insulator or many others electrical equipment. Engineering plastics have good characteristic (light weight, good productivity and little of void) as compare with epoxy or porcelain insulators. Outdoor insulator must have resistance to contamination. However, it isn't suited to outdoor insulator because it is not hydrophobic. RTV(Room temperature vulcanizing) has a good property of hydrophobic and micro-filler. nano-filler have characteristics of obstructing exothermic reaction. In order to reduce the incidence of insulator flashover and damage, the silicon rubber contained with micro, nano-filler coating on surface of engineering plastics. In this paper, it compares tracking resistance, leakage current of the engineering plastic coated RTV with that of non-coated engineering plastic. And filled-composites performed much better than non-filled composites.

• Elastomers and Composites
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• 제22권3호
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• pp.213-218
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• 1987

고무중에서 polymer melt와 가장 유사한 유변학적 거동을 보이는 EPDM을 택하여, 가황반응속도를 조사하였으며, 이에 따라 부분적으로 가교도를 달리한 시편의 유변학적 특성을 capillary rheometer를 사용하여 검토하였다. 가교도가 0, 1.5, 3, 6%로 증가함에 따라 die 입구 및 출구에서의 압력 손실은 커지고, melt fracture가 일어나는 전단속도는 낮아지며 특히 die swell은 거의 직선적으로 증가하였다. 본 연구를 통하여 die swell, melt fracture, end effects등의 근원이 고분자 사슬의 탄성변형에 있음을 확인하였으며, 또한 압출, 압연등에서 흔히 관측되는 die swell의 요동이 가공중 발생할 수 있는 가황반응에 기인할 수도 있음을 보여준 것이다.

• Elastomers and Composites
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• 제40권4호
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• pp.237-241
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• 2005

스티렌 함량이 SBR 가황물의 회복 거동에 미치는 영향에 대해 연구하였다. 스티렌 함량이 15와 21 wt%인 SBR을 사용하였다. 스티렌 함량이 적은 가황물이 스티렌 함량이 많은 가황물에 비해 더 낮은 온도에서 회복하기 시작하였으며, 스티렌 함량이 적은 가황물의 회복 속도가 스티렌 함량이 많은 가황물보다 느렸다. 두 가황물 간의 회복 차이는 카본블랙으로 보강된 가황물이 실리카로 보강된 것보다 컸다. 실험 결과는 유리전이온도와 모듈러스로 설명하였다.

• Elastomers and Composites
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• 제54권2호
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• pp.135-141
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• 2019

Polyphenylene sulfide (PPS) was filled with glass fiber (GF), aramid fiber (AF), and solid lubricants to improve the mechanical properties and wear resistance. The addition of GF effectively enhanced the tensile strength, flexural modulus, and impact strength of PPS, while solid lubricants such as polytetrafluoroethylene (PTFE), molybdenum disulfide ($MoS_2$), and tungsten disulfide ($WS_2$) lowered the friction coefficients of the composites to below 0.3. The ball nut and motor pulley of the electric power steering (EPS) were manufactured using the PPS composites, and feasibility was ascertained thereafter by conducting the durability test. The composites filled with GF and AF showed high mechanical strength, but slip occurred at the interface between the pulley and belt while testing above $50^{\circ}C$. When small amounts of lubricants were added, the slip was no longer detected because of the suppression of friction heat. It is realized that the low friction as well as high mechanical properties is important to ensure the reliability of plastic pulleys.