• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 춘계 학술논문 발표대회 1부
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• pp.55-56
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• 2011

This paper is to compare and analyze the properties of ultra high strength concrete depending on the use of SF aiming for applicability of superplasticizer containing CASB as a functional agent for strength improvement. As experimental results, in case superplasticizer containing CASB is used, regardless of W/B, settiing time was more accelerated than N, and both compressive strength and tensile strength showed an increase in their strength minutely.

• 한국세라믹학회지
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• 제26권2호
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• pp.195-200
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• 1989

The Silica-Carbon mixture was made with addition of carbon black in the composition which monodispersed spherical fine silica was formed by the hydrolysis of ethylsilicate, mole ratio of Carbon/Alkoxide was 3.1 and $\beta$-SiC powder was synthesized by reacting this mixture at 1,350~1,50$0^{\circ}C$ in Ar atmosphere. The results of this study are as follow : (1) The purity of synthesized $\beta$-SiC powder was above 99.98% and it was in cubic modification with lattice constant of 4.3476$\AA$. (2) The rate-controlling steps varied with the reaction temperature for the syntehsis of $\beta$-SiC in this study ; nucleation and growth of $\beta$-SiC at 1,350~1,40$0^{\circ}C$, interfacial reaction at 1,45$0^{\circ}C$ and diffusion described by Jander Equation at 1,50$0^{\circ}C$. (3) When the rate-determining step was nucleation and growth, the activation energy was about 87.8kcal/mol.

• Elastomers and Composites
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• 제41권4호
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• pp.260-267
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• 2006

유기화 클레이(organically modified layered silicates)가 보강된 SBR 나노 복합체를 라텍스법(latex method)에 의해서 제조하였다. 유기화 MMT는 dodecylamine으로 유기화한 DA-MMT와 dimethyldodecylamine으로 유기화한 DDA-MMT의 두 가지를 제조하였다. 유기화 클레이의 층간거리와 분산도를 확인하기 위하여 XRD와 TEM촬영을 하였다 Na-MMT, DA-MMT, DDA-MMT의 XRD 회절 패턴을 분석한 결과 Na-MMT는 $2{\theta}=7.2^{\circ}$로써 층간거리가 $12.3{\AA}$, DA-MMT는 $2{\theta}=5.1^{\circ}$로 층간거리가 $17{\AA}$를 나타내었으며, DDA-MMT의 경우, 회절 피크는 $2{\theta}=4.8^{\circ}$로써. 층간거리는 $18.4{\AA}$으로 나타났다. 이는 DDA-MMT와 DA-MMT가 각각 5 phr 첨가된 SBR 나노 복합체의 TEM 결과에서도 확인할 수 있었다. SBR 나노 복합체에 filler system (carbon black/silica/OLS)을 적용 후 시편을 제조하였다. 제조된 시편의 동적 점탄성 평가 (DMTA)는 $-20^{\circ}C{\sim}80^{\circ}C$ 사이에서 이루어졌으며, loss factor (tan $\delta$)의 거동을 확인하였다. 그 결과, 타이어 트래드용 컴파운드를 대상으로 할 경우, 카본블랙과 실리카의 혼용비가 35:25일 때, 빗길 제동특성과 연비특성을 대변하는 $0^{\circ}C$와 $50{\sim}60^{\circ}C$에서의 tan $\delta$가 가장 우수함을 알 수 있었다. 또한 이 시스템에 실리카의 일정 부분을 DDA-MMT($0{\sim}10phr$)로 대체할 경우, $0^{\circ}C$의 tan $\delta$값은 높아지는 반면, $50{\sim}60^{\circ}C$의 tan $\delta$값은 감소하였다.

• Elastomers and Composites
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• 제44권3호
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• pp.336-342
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• 2009

1.0 wt% 소수성실리카를 안정제로 하는 현탁중합에 의하여 $75^{\circ}C$에서 개시제의 농도를 변화하며 합성한 폴리스티렌 (PS) 및 폴리뷰틸메타크릴레이트 (PBMA) 입자의 점도를 모세관 레오미터 (capillary rheometer)를 이용하여 측정하였다. 중량평균분자량이 66,500 g/mol인 PS 입자는 $190^{\circ}C$에서 측정한 경우 낮은 전단속도에서는 뉴톤 (Newtonian) 거동을 나타내었다. PS 입자의 경우 분자량이 증가할수록 전단속도 전 영역에서 전단 묽어짐 (shear thinning) 거동을 보였다. PBMA 입자는 $170^{\circ}C$에서 점도를 측정하였으며 중량평균분자량이 156,700 g/mol 인 경우 낮은 전단속도에서만 뉴톤 거동을 나타내었다. 분자량의 증가에 따라 전단 묽어짐 거동이 관찰되었으며, 이러한 변화의 형태는 PS 입자와 유사하였다. 카본블랙을 충전제로 합성한 고분자 복합체 입자의 전단점도는 PS 및 PBMA 둘 다 $170^{\circ}C$에서 측정하였다. PS 및 PBMA 복합체 입자의 점도변화는 카본블랙의 증가에 따라 점진적으로 증가하였으나, 충전제의 증가에 따른 점도의 증가는 분자량의 증가 효과에 비교하여 미약하였다. 내부혼합기를 이용하여 제조한 카본블랙을 함유하는 PS 복합체의 점도변화는 현탁중합법으로 합성한 카본블랙을 함유하는 PS 복합체 입자의 점도변화에 비하여 작았으며 이는 향상된 분산으로 인하여 발생한 것으로 추정된다. 이 실험에서 선택한 분자량 및 카본블랙의 농도에서 yield 거동은 관찰되지 않았다.

• Macromolecular Research
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• 제9권1호
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• pp.45-50
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• 2001

Formation of bound rubber depends on the filler-polymer interactions including physical adsorption, chemisorption, and mechanical interaction. Bound rubbers consist of tightly and loosely bound ones. Styrene-butadiene rubber (SBR) is composed of styrene, 1,2-, cis-1,4-, and trans-1,4-units. Filler-polymer interactions of each components of SBR with fillers, carbon black and silica, were studied by analysis of microstructure of the bound rubber. Filler-polymer interaction of the 1,2-unit with the fillers was found to be stronger than those of the other components and this phenomenon was shown more clearly in the tightly bound rubber.

• 한국전기전자재료학회논문지
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• 제25권3호
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• pp.224-228
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• 2012

We have developed new materials that lead to methyl meth acrylate monomer and styrene monomer to using polymerization method. The materials have a powder form and show liquid behavior. We call the "Electronic Bead". An our experiment, a positive-charged particle has $TiO_2$, polymer and CCA(-), while a negative-charged particle consists of carbon black, polymer and CCA(+). The charged particles have electrical characteristic of white -10 uC/g and black 10 uC/g, respectively. Also, these particles have good fluidity by additive of nano-sized silica. Using these materials, we demonstrated prototype displays that have $320{\times}320$ array of pixels and 6-in-diagonal viewable image size, driven by passive-matrix addressing. The reflectivity shows about 30% even though our experiment is at the beginning point. Also, the panel has contrast ratio 6:1. We think there are many chances to improve reflectivity through modifying components of particle resin, mixture ratio of each particle, panel structure and so on.

• 한국독성학회:학술대회논문집
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• 한국독성학회 2005년도 춘계 국제심포지엄 및 학술대회
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• pp.51-82
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• 2005

To compare the pulmonary toxicity between ultrafine colloidal silica particles (UFCSs) and fine colloidal silica particles (FCSs), mice were intratracheally instilled with 3 mg of 14-nm UFCSs and 230-nm FCSs and pathologically examined from 30 mill to 24 hr post-exposure. Histopathologically, lungs exposed to both sizes of particles showed bronchiolar degeneration and necrosis, neutrophilic inflammation in alveoli with alveolar type II cell proliferation and particle-laden alveolar macrophage accumulation. UFCSs, however, induced extensive alveolar hemorrhage compared to FCSs from 30 min onwards. UFCSs also caused more severe bronchiolar epithelial cell necrosis and neutrophil influx in alveoli than FCSs at 12 and 24 hr post-exposure. Laminin positive immunolabellings in basement membranes of bronchioles and alveoli of UFCSs treated animals was weaker than those of FCSs treated animals in all observation times. Electron microscopy demonstrated UFCSs and FCSs on bronchiolar and alveolar wall surface as well as in the cytoplasm of alveolar epithelial cells, alveolar macrophages and neutrophils. Type I alveolar epithelial cell erosion with basement membrane damage in UFCSs treated animals was more severe than those in FCSs treated animals. At 12 and 24 hr post-exposure, bronchiolar epithelia cells in UFCSs treated animals showed more intense vacuolation and necrosis compared to FCSs treated animals. These findings suggest that UFCSs has greater ability to induce lung inflammation and tissue damages than FCSs.

• 한국세라믹학회지
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• 제55권3호
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• pp.285-289
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• 2018

We synthesized silicon carbide (${\beta}-SiC$) nanowires with nano-scale diameter (30 - 400 nm) and micro-scale length ($50-200{\mu}m$) on a porous body using low-grade silica and carbon black powder by carbothermal reduction at $1300-1600^{\circ}C$. The SiC nanowires were formed by vapor-liquid-solid deposition with self-evaporated Fe catalysts in low-grade silica. We investigated the characteristics of the SiC nanowires, which were grown on a porous body with Ar flowing in a vacuum furnace. Their structural, optical, and electrical properties were analyzed with X-ray diffraction (XRD), transmission electron microscopy (TEM), and selective area electron diffraction (SAED). We obtained high-quality SiC single crystalline nanowire without stacking faults that may have uses in industrial applications.

• Elastomers and Composites
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• 제52권4호
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• pp.280-286
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• 2017

The mechanical and dynamic properties according to the content of filler, plasticizer, and crosslinking agent of rubber composites for Lipseal were measured in this study. The mechanical properties of the composite including the silane coupling agent and silica were found to be superior to those of the composite containing carbon black. It was found that the rebound resilience characteristics were influenced by the crosslink density of sulfur rather than the filler or plasticizer. In the case of recovery, it was confirmed that the elastic restoring force improved in the compression deformation condition and recovery increased as the crosslinking density increased. The rubber composite for Lipseal of this study is expected to improve the manufacturing technology of the rubber composite which can implement the optimum function for recognizing the performance such as oil resistance, durability and compression set.

• Elastomers and Composites
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• 제58권4호
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• pp.179-190
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• 2023

The effect of the particle size and silica structure on the wear behavior of Silica/Styrene-Butadiene Rubber (SBR) compounds was investigated using a blade-type abrader and the findings were compared with those obtained with an Akron abrader. The compensated characteristic parameter (Ψ_c), which was the contributory factor of the combined effect of the particle size and filler structure, was introduced. This parameter was found to exhibit a linear relationship with the Young's modulus. The Young's modulus correlated more with Ψ_c than the uncompensated characteristic parameter (Ψ) modeled for carbon black. The wear rate and volume loss measured using a blade-type abrader and Akron abrader were respectively observed to be inversely proportional to Ψ_c, that is, the wear resistance of Silica/SBR compound improved as the particle size became smaller and the silica structure became intricate. The coefficient of determination (R²) obtained from the linear relationship between Ψ_c and wear rate was higher than those between Ψ_c and volume loss for the Silica/SBR compound. Thus, the blade-type abrader exhibited high potential to be used for accurately evaluating the effect of particle size and structural properties of silica on the wear behavior of SBR compounds.