Heat insulation property silica aerogel/unsaturated polyester composites with preserved aerogel pores using decompression forming

송봉관,홍창국 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0

Silica aerogel/unsaturated polyester composites were fabricated by decompression forming of silica aerogel powders and unsaturated polyester resin. Due to the porous structure, silica aerogel showed extremely low thermal conductivity. But owing to the infiltration of unsaturated polyester resin into aerogel pores, aerogel pores isn’t preserved.A new process was designed to dilate aerogel pores between silica aerogels and unsaturated polyester resin using decompression forming. Well-preserved aerogel pores were observed in the silica aerogel/unsaturated polyester composites using scanning electron microscope and Heat insulation property was indicated thermal conductivity.And it was measured by the plating method.

Thermal conductivity of silica aerogel/unsaturated polyester composites with preserved aerogel pores using room temperature forming

송봉관,홍창국 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0

Silica aerogel/unsaturated polyester composites were fabricated by room temperature forming of silica aerogel powders and unsaturated polyester resin. Due to the porous structure, silica aerogel showed extremely low thermal conductivity. But owing to the attraction of aerogel and polymer resin, aerogel pores isn’t preserved. Polymer resin tend to decrease of mobility at low temperature conditions. A new process was designed to preserve pores between hydrophobic silica aerogels and unsaturated polyester composites using room temperature forming. Well-preserved aerogel pores were observed in the silica aerogel/unsaturated polyester composites using scanning electron microscope and Heat insulation property was indicated thermal conductivity.And it was measured by the plating method.

Improvement in the high temperature thermal insulation performance of Y₂O₃ opacified silica aerogels

Parale, Vinayak G.,Jung, Hae-Noo-Ree,Han, Wooje,Lee, Kyu-Yeon,Mahadik, Dinesh B.,Cho, Hyung Hee,Park, Hyung-Ho Elsevier 2017 Journal of Alloys and Compounds Vol.727 No.-

<P><B>Abstract</B></P> <P>To improve the high-temperature thermal insulation characteristics of silica aerogels, it is important to reduce the radiative heat transfer. This can be achieved by Y<SUB>2</SUB>O<SUB>3</SUB> doping in the silica sol to opacify the infrared radiation of silica aerogels. The purpose of the present work was to study the effect of Y<SUB>2</SUB>O<SUB>3</SUB> incorporation on the structural and physicochemical properties of opacified silica aerogels prepared by a simple ambient pressure drying method. The influence of Y<SUB>2</SUB>O<SUB>3</SUB> addition on specific extinction coefficient and high temperature thermal insulation of prepared aerogels were investigated. The synthesized aerogels were lightweight and crack-free, with a granular, nanoporous morphology. The specific surface area, pore diameter, and bulk density of the prepared samples were 917.5–937.6 m<SUP>2</SUP>/g, 5.64–6.58 nm, and 0.047–0.076 g/cm<SUP>3</SUP>, respectively. The thermal conductivity of opacified silica aerogel at 1000 K was 0.080 W/(m.K), which was lower than the unopacified silica aerogel and it was around 0.104 W/(m.K) at same temperature.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Low density Y<SUB>2</SUB>O<SUB>3</SUB> opacified SiO<SUB>2</SUB> aerogels by APD for HT thermal insulation. </LI> <LI> Y<SUB>2</SUB>O<SUB>3</SUB> effect on structural, physicochemical and morphological properties of aerogels. </LI> <LI> Aerogels: 917.5 m<SUP>2</SUP>/g surface area, 3.422 cm<SUP>3</SUP>/g pore volume, 6.58 nm pore diameter. </LI> <LI> 0.080 W/(m.K) of thermal conductivity of Y<SUB>2</SUB>O<SUB>3</SUB> opacified aerogels at 1000 K. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

2P-157 Fabrication of Nano Porous Silica Aerogel-Polydimethylsiloxane (PDMS) Insulation Film

노영아,김희택,송시내,박성수,심호형,김진이,( Tran Xuan Tin ) 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1

The silica aerogel is a suitable material to apply for insulation material with lower thermal conductivity than that of air to save energy. However expensive precursor and drying process were the main issues of the silica aerogel synthesis. Therefore, we demonstrate an ecofriendly route toward silica-PDMS insulation film with low thermal conductivity under ambient pressure. Silica aerogel was synthesized from rice husk ash, which was an agricultural waste to be able to recycle. The silica aerogel is prepared by sol-gel processing and obtained by modification of silica hydrogel surface and dry at ambient pressure. Finally, aerogel film was respectively fabricated by the different content with aerogel in PDMS. Silica aerogel particle size was analyzed by Scanning electron microscope and silica aerogel with high surface area (832.26 m²/g) was characterized by Brunauer Emmett Teller. Then thermal conductivity of silica Aerogel-PDMS insulation film was analyzed by thermal wave system.

Characterization of Mechanical Property Change in Polymer Aerogels Depending on the Ligand Structure of Acrylate Monomer

Lee, Kyu-Yeon,Jung, Hae-Noo-Ree,Mahadik, D.B.,Park, Hyung-Ho The Korean Microelectronics and Packaging Society 2016 마이크로전자 및 패키징학회지 Vol.23 No.3

In an effort to overcome the weakness of aerogel, polymer aerogels have been prepared by copolymerizing the different types of monomers through sol-gel process. Polymerizing the successive phase of a high internal phase emulsion, which has interconnected porous structure, porous polymer aerogel can be manufactured. In this paper, we use the styrene/divinylbenzene chain as a basic monomer structure, and additionally use 2-ethylhexyl methacrylate (2-EHMA) or 2-ethylhexyl acrylate (2-EHA) as monomers for distinguishing the visible mechanical properties of synthesized polymer aerogel. We can observe the different tendency of polymer aerogels by kinds of monomer or ratio. Flexibility and microstructure can be changed by the types of monomer. EHA polymer aerogel shows high flexibility and thin microstructure, and EHMA polymer aerogel shows high hardness and thick microstructure. EHA/EHMA polymer aerogel shows the intermediate nature between them. By utilizing the mechanical properties of three types of polymer aerogels to adequate situation or environment, polymer aerogels could be used as drug agent, ion exchange resin, oil filter and insulator, and so on.

Ambient pressure dried tetrapropoxysilane-based silica aerogels with high specific surface area

Parale, Vinayak G.,Han, Wooje,Jung, Hae-Noo-Ree,Lee, Kyu-Yeon,Park, Hyung-Ho Elsevier 2018 Solid state sciences Vol.75 No.-

<P><B>Abstract</B></P> <P>In the present paper, we report the synthesis of tetrapropoxysilane (TPOS)-based silica aerogels with high surface area and large pore volume. The silica aerogels were prepared by a two-step sol-gel process followed by surface modification via a simple ambient pressure drying approach. In order to minimize drying shrinkage and obtain hydrophobic aerogels, the surface of the alcogels was modified using trichloromethylsilane as a silylating agent. The effect of the sol-gel compositional parameters on the polymerization of aerogels prepared by TPOS, one of the precursors belonging to the Si(OR)<SUB>4</SUB> family, was reported for the first time. The oxalic acid and NH<SUB>4</SUB>OH concentrations were adjusted to achieve good-quality aerogels with high surface area, low density, and high transparency. Controlling the hydrolysis and condensation reactions of the TPOS precursor turned out to be the most important factor to determine the pore characteristics of the aerogel. Highly transparent aerogels with high specific surface area (938 m<SUP>2</SUP>/g) and low density (0.047 g/cm<SUP>3</SUP>) could be obtained using an optimized TPOS/MeOH molar ratio with appropriate concentrations of oxalic acid and NH<SUB>4</SUB>OH.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Optically transparent and hydrophobic silica aerogel using TPOS was successfully synthesized. </LI> <LI> Sol-gel compositional effect using TPOS on the polymerization of aerogels was firstly reported. </LI> <LI> MeOH/TPOS and acid/base concentrations strongly influenced on the physical and textural properties. </LI> <LI> High surface area (938 m<SUP>2</SUP>/g) and low density (0.047 g/cm<SUP>3</SUP>) are obtained using TPOS as precursor. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effect of fiber surface-treatment on the properties of ceramic fiber reinforced silica aerogel blanket

송봉관,홍창국 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0

Silica aerogel is a porous-structured material with low thermal conductivity. Due to this thermal property, silica aerogel has attracted attention for their wide range of applications such as thermal insulator, wave adsorption. However, from the point of view of applications, aerogel has poor mechanical property and it makes they cannot be easily handled. Therefore, fiber-reinforced aerogel blanket has been prepared as an alternative to improve mechanical property. In this study, ceramic fiber reinforced silica aerogel blankets for insulation were prepared under ambient drying using sodium silicate as a source of silica and TMCS as a surface modification agent. The ceramic fiber as a supporting skeleton. To increase thermal insulation property of silica aerogel blanket, its surface treated with acid to enhance compatibility between fiber and aerogel. The silica aerogel blanket is characterized by scanning electron microscope, Fourier transform infrared spectroscopy.

하이퍼써미아 응용을 위한 하이브리드 에어로젤 내 분산된 마그네타이트 나노입자

이은희,좌용호,김창열,Lee, Eun-Hee,Choa, Yong-Ho,Kim, Chang-Yeoul 한국재료학회 2012 한국재료학회지 Vol.22 No.7

Magnetite nanoparticles(NPs) have been the subject of much interest by researchers owing to their potential use as magnetic carriers in drug targeting and as a tumor treatment in cases of hyperthermia. However, magnetite nanoparticles with 10 nm in diameter easily aggregate and thus create large secondary particles. To disperse magnetite nanoparticles, this study proposes the infiltration of magnetite nanoparticles into hybrid silica aerogels. The feasible dispersion of magnetite is necessary to target tumor cells and to treat hyperthermia. Magnetite NPs have been synthesized by coprecipitation, hydrothermal and thermal decomposition methods. In particular, monodisperse magnetite NPs are known to be produced by the thermal decomposition of iron oleate. In this study, we thermally decomposed iron acetylacetonate in the presence of oleic acid, oleylamine and 1,2 hexadecanediol. We also attempted to disperse magnetite NPs within a mesoporous aerogels. Methyltriethoxysilicate(MTEOS)-based hybrid silica aerogels were synthesized by a supercritical drying method. To incorporate the magnetite nanoparticles into the hybrid aerogels, we devised two methods: adding the synthesized aerogel into a magnetite precursor solution followed by nucleation and crystal growth within the pores of the aerogels, and the infiltration of magnetite nanoparticles synthesized beforehand into aerogel matrices by immersing the aerogels in a magnetite nanoparticle colloid solution. An analysis using a vibrating sample magnetometer showed that approximately 20% of the magnetite nanoparticles were well dispersed in the aerogels. The composite samples showed that heating under an inductive magnetic field to a temperature of $45^{\circ}C$ is possible.

Three-dimensional barium-sulfate-impregnated reduced graphene oxide aerogel for removal of strontium from aqueous solutions

Jang, Jiseon,Lee, Dae Sung Elsevier 2018 Journal of nuclear materials Vol.504 No.-

<P><B>Abstract</B></P> <P>A three-dimensional barium-sulfate-impregnated reduced graphene oxide (BaSO<SUB>4</SUB>-rGO) aerogel was successfully synthesized by a facile one-step hydrothermal method and was used as an adsorbent to remove strontium from aqueous solutions. The characterized elemental composition, crystal structure, and morphology of the prepared aerogel confirmed that barium sulfate particles were firmly anchored on the surface of the rGO sheets and exhibited a porous 3D structure with a high surface area of 129.37 m<SUP>2</SUP>/g. The mass ratio of BaSO<SUB>4</SUB> in the BaSO<SUB>4</SUB>-rGO aerogel substantially affected strontium adsorption, and the optimal BaSO<SUB>4</SUB>/rGO ratio was found to be 1:1. The synthesized BaSO<SUB>4</SUB>-rGO aerogel not only reached adsorption equilibrium within 1 h, but also showed much higher adsorption capacity than an rGO aerogel. The experimental data were well fitted to a pseudo-second-order kinetic model and the adsorption behavior followed the Langmuir isotherm. The adsorption capacity of strontium on BaSO<SUB>4</SUB>-rGO aerogels remained relatively high even under ionic competition in simulated seawater. These results showed that the BaSO<SUB>4</SUB>-rGO aerogel is an efficient and promising adsorbent for the treatment of strontium in aqueous solutions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> 3D barium-sulfate-impregnated reduced graphene oxide aerogels were synthesized. </LI> <LI> The mass ratio of BaSO<SUB>4</SUB> in the aerogels substantially affected strontium adsorption. </LI> <LI> The Langmuir isotherm gave the best fit to the experimental adsorption data. </LI> <LI> The strontium adsorption capacity was relatively high even with competing ions in simulated seawater. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Synthesis of Monolithic Titania-Silica Composite Aerogels with Supercritical Drying Process

Kim, Won-Il,Hong, In-Kwon 한국공업화학회 2003 Journal of Industrial and Engineering Chemistry Vol.9 No.6

Monolithic titania-silica composite aerogels have been prepared by complexation and impregnation methods. In the case of complexation method, monolithic titania-silica composite aerogels had good transparency and homogeneity. Particularly, the sol-gel reaction rate was successfully controlled by modifying tetrabutyl orthotitanate (TBOT) with acetylacetone, and the resulting titania-silica composite aerogel bad very high specific surface area. From W-vis diffuse reflectance spectra and FT-IR spectra, it was evident that the resulting titania-silica composite aerogels had homogeneous Si-0-Ti bonds. However, they had more crack and shrinkage than those prepared by impregnation method after supercritical drying and calcination. It was possible to produce crack-free titania-silica composite aerogels hy impregnation method, hut those composite aerogels showed some drawbacks of low Ti contents and non-uniformly distributed Ti phase. We have investigated the influence of addition of various polymers on the synthesis of monolithic aerogel. As a result, it was possible to enhance the hardness of gel network and consequently get a crack-free titania-silica composite aerogel.