• Composites Research
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• 제35권6호
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• pp.412-418
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• 2022

메타크릴산과의 에스터화 반응을 통해 브롬화 에폭시 수지와 일반 에폭시 수지의 혼합물로부터 난연성 비닐에스터 핫멜트 필름을 제조하였고 이를 이용하여 탄소섬유와 비닐에스터 복합 프리프레그를 제조하였다. 저점도 비스페놀-A와 고점도 브롬화 비스페놀-A 에폭시 전구체를 혼합하여 필름 생산에 적합한 VE 수지의 점도를 최적화하였다. 경화된 VE 수지의 브롬 함량 증가는 비 브롬화 VE에 비해 제한 산소 지수(LOI)(39%), 25℃에서의 저장 탄성률(2.4 GPa) 및 잔류 탄화물(16.1%) 값을 더 증가시켰다. 합성한 VE 프리프레그의 수동 레이업과 후속 경화로 인장 및 굴곡 강도가 우수한 CF 강화 복합재를 성공적으로 제작하였다. 본 연구 결과는 스티렌이 없는 친환경적인 VE 복합 재료 공정의 향후 산업화에 대한 높은 가능성을 보여준다.

• 한국산학기술학회논문지
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• 제12권10호
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• pp.4673-4678
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• 2011

이 연구에서는 고분자 전해질 막 연료전지의 분리판 용 고분자/흑연 복합소재의 혼합 특성 및 점도 측정 방법에 관하여 연구하였다. 분리판은 전도성이 있어야 하기 때문에 흑연의 함량이 매우 높고 이 때문에 제조된 복합재료의 점도가 높아 점도 측정이 어려운 문제가 있다. 일반적으로 캐필러리 레오메터에서 사용되는 다이로 점도를 측정한 결과 압력이 시간에 따라서 계속 변하고 정상상태의 값을 보이지 않아서 점도 측정이 불가능 했다. 다이의 디자인을 변경하여 측정하면 압력이 정상상태를 보이는 것을 관찰할 수 있었으나, 흑연과 PET를 단순 용융 혼합하여 점도를 측정하는 경우에는 측정된 점도 값이 재현성이 없는 결과를 나타냈다. 여러 차례의 시행 오차 끝에 흑연과 PET를 작은 입자로 분쇄한 후 용융 혼합하면 재현성 있는 점도를 측정할 수 있고, 제조된 복합재료의 전기전도도 값도 재현성 있는 결과를 보임을 관찰하였다.

• 대한금속재료학회지
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• 제48권2호
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• pp.154-162
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• 2010

A fundamental study of the distillation behavior of ferromanganese alloy melts was carried out at 1773 K and 0.1333 kPa (=1 Torr). During the distillation of ferromanganese alloy melts under reduced pressure, manganese vaporizes preferentially to phosphorus and other solute elements. High purity manganese metal with a very low content of solute elements can be obtained by distillation of ferromanganese alloy melts. The evaporation of manganese is suppressed as the carbon content of ferromanganese alloy melt increases due to the decrease of activity and vapor pressure of the manganese. When the carbon content of ferromanganese alloy melt is high, melt droplets are ejected from the bath, especially in the early stages of the distillation, and the solute elements in the splashed droplets contaminate the condensed material. The ejection of melt droplets is presumed to be caused by the increase of melting temperature and viscosity of the surface layer of melt due to the enrichment of solute elements such as carbon and iron.

• 한국식품조리과학회지
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• 제12권1호
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• pp.20-26
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• 1996

The present study was attempted to investigate and to evaluate various hydrocolloids as a stabilizer in improving texture of the frozen yogurt. Four kinds of hydrocolloids used in this study were CMC (carboxymethyll cellulose), PGA(propylene glycol alginate), LMP(low methoxyl pectin), and the combination of LBG(locust bean gum) and GG(guar gum). The viscosity of frozen yogurt mixes did not show any significant differences among four samples at 5$^{\circ}C$. However, as the temperature increased up to 50$^{\circ}C$, theviscosity of frozen yogurt mixes containing CMC, LMP, PGA decreased drastically except frozen yogurt containing the combination of LBG+GG. The overrun of frozen yogurt containing each hydrocolloid gradually increased and reached to about 53, 50, 54, and 35%, respectively, after 40 min of operating ice cream freezer. As the result of sensory evaluation in the texture of frozen yogurt and melt-down quality, the sample containing LMP was described as the most coarce & icy, crumbly, and sand-like characters. On the other hand, PGA sample was evaluated as not being icy, crumbly, but being chewy and soft in texture. However, any significant differences among four samples were not shown in melt-down quality.

• 한국세라믹학회지
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• 제30권1호
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• pp.7-16
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• 1993

Effect of sulfate on the reactionof C3S formation in presence of clinker melt and its appearance in clinker were investigated, using (NH4)2SO4 and CaSO4 as sulfate sources. When (NH4)2SO4 and CaSO4 were added, both showed the similar results, 1.0wt% of sulfate could promoted the reaction of C3S formation, however for its content of more than 2.0wt%, the formation of C3S was prevented. Residual limit of sulfate to C3S formation is about 1.4wt%. Appearances of sulfate were C4A3l and CaSO4 in interstitial phase. For the addition of (NH4)2SO4 or CaSO4 of 20wt%~4.0wt%, C3S grains showed the hypertrophic growth. We might consider that, because sulfate reduced the surface tension and viscosity of the clinker melt, C3S crystals were precipitated below 140$0^{\circ}C$, and the crystlas of C3S were coalesced and linked in the same crystallographical direction with increasing temperature becuase of their rapid growth rate.

• Macromolecular Research
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• 제10권4호
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• pp.221-229
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• 2002

PET nanocomposites filled with fumed silicas were prepared via direct melt compounding method at various mixing conditions such as filler type and filler content. Some fumed silicas were pre-treated to improve the wettability and dispersibility, and principal characterizations were performed to investigate the effects of nano fumed silicas on polymer matrix. Hydrophobic fumed silica (M-FS), which has the similar contact angles of water with neat PET, acted as the best reinforcement for the thermal stability and mechanical properties of PET nanocomposite, and FE-SEM images also showed that M-FS was uniformly dispersed into matrix and had good wettability. But, some filler (O-FS) had low dispersibility and caused the deterioration of mechanical properties. Besides, the results of DSC revealed the nucleation effect of all fillers in polymer matrix, and PET nanocomposite filled with hydroptilic fumed silica (FS) showed markedly the characteristic dynamic rheological properties such as shear thinning behavior at very low frequencies and the decrease of viscosity.

• 전기학회논문지
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• 제65권3호
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• pp.499-503
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• 2016

For safety and economy reasons, hazardous waste including radioactive waste is desired to be converted into stable waste forms with a maximum volume reduction. High temperature melting technology using a plasma torch system can effectively treat even the non-flammable waste as desired. By far, one of the most difficult process for melting the non-flammable waste is a tapping of melts because the melting point of a residual slag in the tapping hole is high and because the viscosity of the melt increases sharply when tapping out. In case of a stationary furnace with a slant tapping port on the side of furnace, a certain amount of melts is left in the tapping hole after tapping out. Because of this, at every end of a melting cycle, the tapping hole needs to be opened by tapping device. The developed tapping device of melts based on both a guide electrode and auxiliary electrode is adequate for the application to discharge of melts except that the consumption of the guide electrode is somewhat faster than expected. Melt is collected in the water cooled vessel.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2002년도 봄 학술발표회 논문집
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• pp.309-312
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• 2002

The polymer nanocomposites are attracting considerable attention on account of the characteristic properties of nanoparticles have extremely large surface area per a unit mass. Recentry, mica-type silicates like montmorillonite have received a good deal of attention as effective nano-reinforcemen(1), but actually some critical problems such as the difficulties of exfoliation and surface modification, the weak heat-resistance of modifier, and inferior processability due to the increase in melt viscosity have restricted the mass production and various applications of the nanocoposite. (omitted)

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.364-364
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• 2006

The rheological properties of Parmax 1200, a new semi-flexible substituted polyphenylene, were investigated. The reported high stiffness of the material was confirmed. The rheological measurements proved that, despite the very high stiffness of the molecules, Parmax showed shear thinning and that, although the viscosity is very high and the melt is highly elastic, the polymer can be extruded in the melt. A worm-like morphology was detected in AFM and TEM. This morphology could explain the reported mechanical and rheological behaviour. The compatibility with flexible chain polymers (e.g. polycarbonate) could also be explained by the worm-like morphology.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.505-506
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• 2006

This study is focused on the manufacturing technique of powder injection molding of watch case made from zirconia powder. A series of computer simulation processes were applied to the prediction of the flow pattern in the inside of the mould and defects as weld-line. The material properties of melted feedstock, including the PVT graph and thermal viscosity flowage properties were measured to obtain the input data to be used in a computer simulation. Also, a molding experiment was conducted and the results of the experiment showed a good agreement with the simulation results for flow pattern and weld line location. On the other hand, gravity and inertia effects have an influence on the velocity of the melt front because of the high density of ceramic powder particles during powder injection molding in comparison with polymer's injection molding process. In the experiment, the position of the melt front was compared with the upper gate and lower gate positions. The gravity and inertia effect could be confirmed in the experimental results.