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A platform for research: civil engineering, architecture and urbanism
Size and microstructure control of calcium aluminate microcapsules
Microencapsulation is nowadays widely applied for the separation or controlled and targeted release of substances. In the present work we propose using particle-stabilized water-in-oil emulsions to produce microcapsules from calcium aluminate cement. First, we investigate the parameters determining the capsule size and size distribution. Then, the anhydrous particles at the water-oil contact line are hydrated resulting in the formation of a layer of precipitated calcium aluminate hydrate that strengthens the capsule shells. By manipulating the hydration reaction of the cement particles, the capsule shell thickness is varied between 200 nm and 1300 nm. For hydration temperatures of 3 °C and 25 °C, the capsule walls are mainly formed from Ca2Al2O5 · 8H2O, whereas Ca2Al2O5 · 8H2O and the stable γ-Al(OH)3 and Ca3Al2O6 · 6H2O phases are precipitated at 60 °C. In addition, the impact of these manipulations on the yield of dry microcapsules is discussed. The highest yield of intact capsules observed in this study is (72 +/- 3) %. We believe that such microcapsules can lead to new applications, particularly in environments with harsh conditions or in inorganic matrixes.
Size and microstructure control of calcium aluminate microcapsules
Microencapsulation is nowadays widely applied for the separation or controlled and targeted release of substances. In the present work we propose using particle-stabilized water-in-oil emulsions to produce microcapsules from calcium aluminate cement. First, we investigate the parameters determining the capsule size and size distribution. Then, the anhydrous particles at the water-oil contact line are hydrated resulting in the formation of a layer of precipitated calcium aluminate hydrate that strengthens the capsule shells. By manipulating the hydration reaction of the cement particles, the capsule shell thickness is varied between 200 nm and 1300 nm. For hydration temperatures of 3 °C and 25 °C, the capsule walls are mainly formed from Ca2Al2O5 · 8H2O, whereas Ca2Al2O5 · 8H2O and the stable γ-Al(OH)3 and Ca3Al2O6 · 6H2O phases are precipitated at 60 °C. In addition, the impact of these manipulations on the yield of dry microcapsules is discussed. The highest yield of intact capsules observed in this study is (72 +/- 3) %. We believe that such microcapsules can lead to new applications, particularly in environments with harsh conditions or in inorganic matrixes.
Size and microstructure control of calcium aluminate microcapsules
Sturzenegger, Philip N. (author) / Gonzenbach, Urs T. (author) / Martynczuk, Julia (author) / Gauckler, Ludwig J. (author)
Journal of the American Ceramic Society ; 95 ; 2481-2490
2012
10 Seiten, 14 Bilder, 3 Tabellen, 22 Quellen
Article (Journal)
English