• Textile Coloration and Finishing
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• v.25 no.4
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• pp.279-286
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• 2013

Application properties of ultra light weight silica aerogel toward polyurethane membranes were investigated. From the results of pre-milling process of the silica aerogel, the solvent for dispersion of the aerogel was determined for methyl ethyl ketone and its content in the solvent was determined by 30%. Using this aerogel dispersion, the polyurethane membranes were prepared according to the mixing amount of silica aerogel and various properties of the membranes were investigated. As results, the optimum mixing amount of silica aerogel inside polyurethane membranes was decided at 11%, because the improvement of light weight property, air permeability, and moisture vapor permeability were improved upto 11% of silica aerogel content, maintaining the water penetration resistance almost unchanged.

• Journal of the Korean Ceramic Society
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• v.36 no.11
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• pp.1189-1197
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• 1999

Low-density silica gel monolith was synthesized at ambient pressure by surface modification with TMCS and sub-sequent heat treatment. The mechanical thermal and optical properties of gel were studied. Compressive strength and modulus of compression of 350$^{\circ}C$-heated gel with the density of 0.24g/cm3 were 250kPa and 0.2MPa respectively. The thermal conductivity of silica gels synthesized at ambient pressure exhibited 0.02 W/m$.$K for the density of 0.24g/cm3 which is similar to that of the gel via supercritical drying and their main thermal transfer mechanism is considered to be solid and radiation conduction at room temperature. Ambient-dried silica gels were transparent blue showing about 60% of transmittance in the wavelength of 1500-2100nm and typical absorption bands of existing bonds under heat treatment at 350$^{\circ}C$. Medium scale monolity(${\Phi}$=50mm) at ambient pressure could be successfully prepared through total 5-month process period.

• 기계와재료
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• v.22 no.4
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• pp.6-20
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• 2010

현재 우리나라는 에너지 소비량의 97% 이상을 해외에 의존하고 있으며, 그 규모가 매년 증가하고 있는 실정이다. 이를 해소하기 위하여 다양한 시도가 이루어지고 있으며 이에 따른 관련 연구 분야의 정부 정책 지원도 증가하는 추세이다. 그러나 새로운 차세대 단열 소재의 개발을 통한 에너지 절감에 대한 노력은 아직 미흡한 상태이다. 본고에서는 이와 관련하여 에너지 효율 극대화 방안으로써, 기존의 단열 소재의 현황 및 향후 단열 소재의 연구방향을 다공질 세라믹(특히 에어로겔)을 중심으로 정리 기술함으로써 앞으로의 발전방향을 제시하고자 한다. 또한 이를 통하여 전체적인 다공성 무기질 단열 소재에 대한 이해를 높여 향후 친환경적이며, 에너지 효율적인 단열소재 연구 분야를 확립하는데 기여하고자 한다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.9
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• pp.1362-1367
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• 2012

High porous silica aerogel/polyurethane polymer composite was manufactured by cross-linking polymerization of polyurethane foaming process. The properties of microstructure, mechanical strength, and thermal properties were investigated for its various applications. The superhydrophobic silica aerogel powders were used for highly thermal insulation filler materials. The thermal conductivities can be resulted 0.07 W/mK to 0.13 W/mK, by decreasing the contents of silica aerogels in composite materials. It is found that the polymerization formulation by organic binders can be applied to heavy industires, building materials, and various industries.

• Journal of the Korean Ceramic Society
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• v.36 no.3
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• pp.307-318
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• 1999

동결건조법에 의한 저유전성 실리카 박막의 제조공정 개발 및 층간 절연물질로의 응용성이 연구되었다. 코팅용 폴리머 실리카 졸은 TEOS와 이소프로판올(iso-propanol:IPA)또는 터트부탄올(tert-butanol:TBA)을 용매로한 2단계 공정에 의하여 제조되었으며, 이들 졸을 p-Si(111)웨이퍼 상에 스핀코팅한 습윤겔 박막을 동결건조 하여 다공성 실리카 박막을 제조하였다. 균일한 박막 코팅층을 얻을 수 있는 실리카 졸의 최적 점도범위는 IPA와 TBA를 용매로 한 실리카 졸의 경우 각각 10~14 cP와 20~30cP 정도였으며 스핀속도는 2000 rpm 이상이었다. 결함이 없는 다공성 실리카 박막은 TBA(빙점 $25^{\circ}C$)를 동결용매로 하여-196$^{\circ}C$까지 급랭시킨 후 $0^{\circ}C$와 0.1 torr 까지 가열 감압한 상태에서 고상의 TBAFMF 모두 제거한 다음 20$0^{\circ}C$까지 열처리하여 제조되었다. 다공성 실리카 박막의 두께는 졸의 타입과 스핀코팅 속도에 의해 2500~15000$\AA$범위 내에서 제어가 가능하였으며 이들 막의 밀도와 유전상 수 값은 각각 0.9$\pm$0.3g/㎤(기공율 60$\pm$10%)과 2.4 정도였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.8
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• pp.660-666
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• 2010

Carbon aerogels are promising materials as electrodes for electrical double layer capacitors (EDLCs). An optimum process is presented for synthesis of nanoporous carbon aerogels via pyrolyzing resorcinol-formaldehyde (RF) organic aerogels, which could be cost-effectively manufactured from RF wet gels. The major reactions between resorcinol and formaldehyde include an addition reaction to form hydroxymethyl derivatives ($-CH_2OH$), and then a condensation reaction of the hydroxymethyl derivatives ($-CH_2-$)- and methylene ether ($-CH_2OCH_2-$) bridged compounds. The textural properties of carbon aerogels obtained were characterized by nitrogen adsorption/desorption analysis and SEM and TEM. The application of the resultant carbon for electrodes of electric double layers capacitor (EDLC) in organic TEABF4/ACN electrolyte indicated that the ESR, as low as 55 $m{\Omega}$, was smaller than for commercially activated carbons. And EDLC with carbon Aerogel electrodes has an excellent stable more than for commercially activated carbons.

• Journal of the Korean Ceramic Society
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• v.34 no.9
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• pp.969-978
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• 1997

The properties of microstructure, hydrophobicity/hydrophilicity, mechanical strength, and thermal conduction of pure/opacified silica aerogels synthesized by the sol-gel supercritical drying technique were investigated. The hydrophobic surface of opacified silica aerogels doped with carbon (0.13 g/cm3 density, 94% porosity, 580 m2/g specific surface area) transformed to hydrophilic surface after heat-treated above 30$0^{\circ}C$. The values of compressive modulus (1.85 MPa) and strength (0.5 MPa) of opacfied silica aerogels were about 20 times higher than those of pure silica aerogels. The mechanical properties of pure silica aerogels heat-treated at $700^{\circ}C$ were also considerably improved without changing their porosity and density. Particularly, compressive modulus and compressive strength of pure silica aerogels GPSed under 100$0^{\circ}C$ and 80 bar were improved 140 and 37 times, respectively. Thermal conductivities of pure/opacified silica aerogels measured at room temperature and 227$^{\circ}C$ were about 0.013 and 0.019 W/m.K, respectively, and were to be found very low value of 0.004 W/m.K below 10 torr pressure at room temperature.

• Journal of the Korean Ceramic Society
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• v.47 no.6
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• pp.553-559
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• 2010

The synthesis behavior of nanoporous silica aerogel in the macroporous ceramic structure was observed using TEOS as a source material and glycerol as a DCCA(dry control chemical additive). Silica aerogel in the macroporous ceramic structure were synthesized through a sono-gel process. The wet gel in the macroporous ceramic structure were aged in ethanol for 72 h at $50^{\circ}C$. The aged wet gel was dried under supercritical drying condition. The addition of glycerol has a role of giving the uniform pore size distribution. The reproducibility of aerogel in the macroporous ceramic was improved in the glycerol(0.05 mol%) added to the silica sol and TEOS : $H_2O$=1 : 12.

• Journal of Powder Materials
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• v.18 no.3
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• pp.269-276
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• 2011

The synthesis behavior of nanoporous silica aerogel in the macroporous ceramic structure was observed using TEOS as a source material and glycerol as a dry control chemical additive (DCCA). Silica aerogel in the macroporous ceramic structure was synthesized via sono-gel process using hexamethyldiazane (HMDS) as a modification agent and n-hexane as a main solvent. The wet gel with a modified surface was dried at $105^{\circ}C$ under ambient pressure. The addition of glycerol appears to give the wet gel a more homogeneous microstructure. However, glycerol also retarded the rate of surface modification and solvent exchange. Silica aerogel completely filled the macroporous ceramic structure without defect in the condition of surface modification (20% HMDS/nhexane at 36hr).

• Journal of the Korean Applied Science and Technology
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• v.27 no.3
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• pp.282-289
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• 2010

In preparation of silica aerogel-based hybrid coating materials, the combination of hydrophobic aerogel with organic polar binder material is shown to be very limited due to dissimilar surface property between two materials. Accordingly, the surface modification of the aerogel would be required to obtain compatibilized hybrid coating sols with homogeneous dispersion. In this study, the surface of silica aerogel particles was modified by using both surfactant adsorption and heat treatment methods. Four types of surfactants with different molecular weights and HLB values were used to examine the effect of chain length and hydrophilicity. The surface property of the modified aerogel was evaluated in terms of visible observation for aerogel dispersion in water, water contact angle measurement, and FT-IR analysis. In surface modification using surfactants, the effects of surfactant type and content, and mixing time as process parameter on the degree of hydrophilicity for the modified aerogel. In addition, the temperature condition in modification process via heat treatment was revealed to be significant factor to prepare aerogel with highly hydrophilic property.