Improved transparent thermal insulation using nano-spaces

Fuji, Masayoshi; Takai, Chika; Watanabe, Hideo; Fujimoto, Kyoichi

doi:10.1016/j.apt.2015.02.012

Cited by 40 publications

(22 citation statements)

References 20 publications

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“…One of the reason is that thermal energy at 700°C didn'ts reach CaCO 3 core owing to SiO 2 's thermal insulation ability. 9) To decrease the thermal insulation effect of SiO 2 coating, the added amount of TEOS was decreased to 0.5 ml. The estimated SiO 2 coating thickness is 2.46 nm.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of CaO@SiO<sub>2</sub> nanoparticle for chemical thermal storage

Yamashita

Fuji

2016

J. Ceram. Soc. Japan

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Preparation of CaO core-SiO 2 shell nanoparticles as a chemical thermal storage through hydration/de-hydration of CaO/ Ca(OH) 2 was proposed. Firstly, SiO 2 was coated on CaCO 3 template surface using solgel route and then the coreshell particles were heated at 700°C to form CaO@SiO 2 nanoparticle by de-carbonization. A thermal storage performance of the CaO@SiO 2 was confirmed by a thermogravimetry (TG) analysis and the result was compared with that of as-received CaCO 3 . The heating program was performed as following steps as (i) at 700°C for 30 min for de-carbonization under nitrogen (N 2 ) atmosphere, (ii) at room temperature for 60 min for hydration under water vapor, and (iii) at 500°C for de-hydration under N 2 . By repeating of (ii) hydration/(iii) de-hydration cycle, effect of the number of cycles on thermal storage ability was investigated. An efficiency of thermal storage was defined as difference in weight change between hydration/de-hydration reactions. For the as-received CaCO 3 nanoparticles, with increase in the number of cycles, the thermal storage performance gradually decreased. The microscopic results showed that the heating cycles induces coalescence of CaCO 3 nanoparticles and that decreases specific surface area. On the other hands, efficiency of thermal storage of CaO@SiO 2 didn't reach theoretical value because CaCO 3 didn't completely transform into CaO owing to SiO 2 's thermal insulation ability. By decreasing SiO 2 coating thickness, the thermal storage performance of CaO@SiO 2 was improved. The microscopic results showed that the SiO 2 coating prevented from coalescence of CaCO 3 nanoparticles.

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Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of CaO@SiO<sub>2</sub> nanoparticle for chemical thermal storage

Yamashita

Fuji

2016

J. Ceram. Soc. Japan

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“…Except for that, the introduction of fillers into polymers can improve the thermal properties. For example, the decomposition temperature and the storage modulus of poly(methyl methacrylate) (PMMA) foams were enhanced by the addition of mesoporous silica …”

Section: Introductionmentioning

confidence: 99%

Microstructural, mechanical, and thermal‐insulation properties of poly(methyl methacrylate)/silica aerogel bimodal cellular foams

Luo

Zhang

et al. 2016

J of Applied Polymer Sci

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Novel poly(methyl methacrylate) (PMMA)/silica aerogel bimodal cellular foams were prepared by melt mixing and a supercritical carbon dioxide foaming process. The effects of the silica aerogel content on the morphologies and thermal-insulating and mechanical properties of the foams were investigated by scanning electron microscopy, mechanical tests, and heat-transfer analysis. The experimental results show that compared to the pure PMMA foam, the PMMA/silica aerogel microcellular foams exhibited more uniform cell structures, decreased cell sizes, and increased cell densities (the densities of the foams were 0.38-0.45 g/cm 3 ). In particular, a considerable number of original nanometric cells (ca. 50 nm) were evenly embedded in the cell walls and on the inner surfaces of the micrometric cells (<10 lm). A 62.7% decrease in the thermal conductivity (0.072 W m 21 K 21 ) in comparison to that of raw PMMA after 0.5 wt % silica aerogel was added was obtained. Mechanical analysis of the PMMA/silica aerogel foams with 5 and 2 wt % silica aerogel showed that the compressive and flexural strengths were distinctly improved by 92 and 52%, respectively, and the dynamic storage moduli increased. The enhanced performance showed that with the addition of silica aerogel into PMMA, one can obtain thermal-insulation materials with a favorable mechanical strength. V C 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44434.

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“…Hollow silica nanoparticles (HSNPs) with inner air cavity and outer silica shell exhibit unique properties, for instance a high specific surface area [1], low density, thermal conductivity [2], and optical property [3][4][5]. They also can be used as a nano-container of solubility materials [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Effects of primary- and secondary-amines on the formation of hollow silica nanoparticles by using emulsion template method

Nakashima

Takai

Razavi‐Khosroshahi

et al. 2016

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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This paper describes the amine effect on sol-gel synthesis which is useful to rapidly form the shell structure of the hollow silica nanoparticles (HSNPs). Poly acrylic acid (PAA)/amine emulsion templates for silica coating performed in ethanol, and the emulsion templates was removed by water to obtain the HSNPs. To investigate of the ionic cross-linker and catalyst abilities of amine, four types of amines; ethylamine (EA), ethylenediamine (EDA), diethylenetriamine (DETA), and triethylenetetramine (TETA) were used. As a result, HSNPs could be successfully synthesized with a high TEOS conversion ratio (95%) and a shorter reaction time (2h) by using EDA, DETA, and TETA. In this procedure, amine worked as the catalyst for sol-gel reaction and the ionic cross-linkers for PAA. In catalyst ability, EDA worked as the most effective catalyst for sol-gel reaction that was measured by the zeta-potential. In cross-link ability, TETA worked as the most effective cross-linker for PAA condensation that was measured by the viscosity measurement. It showed that both cross-link ability and catalyst ability were important factor on this procedure. It was clarified that HSNPs can be synthesized at short time with high conversion ratio by considering the PAA/amine solution viscosity and interaction of amine with alcohol.

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Improved transparent thermal insulation using nano-spaces

Cited by 40 publications

References 20 publications

Synthesis and characterization of CaO@SiO<sub>2</sub> nanoparticle for chemical thermal storage

Synthesis and characterization of CaO@SiO<sub>2</sub> nanoparticle for chemical thermal storage

Microstructural, mechanical, and thermal‐insulation properties of poly(methyl methacrylate)/silica aerogel bimodal cellular foams

Effects of primary- and secondary-amines on the formation of hollow silica nanoparticles by using emulsion template method

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