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| Autor: | Hsin-Chi Tseng, 曾欣琪 |
|---|---|
| Rok vydání: | 2019 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 107 Previously, my senior classmate Li have successfully fabricated flexible nanofibrous membranes made of zirconia via the electrospinning method. He also measured the filtration efficiency of these membranes and showed 99.986% efficiency for 0.3 µm NaCl particles under a cross membrane velocity of 3.3 cm/s and a pressure drop of 299 Pa. My initial attempt was to scale-up his process so that I can produce large enough (35 cm x 35 cm) pieces of membranes and test for other possible applications. However, the first problem I encountered during the scale-up was the environmental issues. The acetic acid solvent used by Li was simply unacceptable for a production plan. Consequently, I have to develop a new recipe. A water-based spinning sol was accomplished by dispersing the acetic ligand capped ZrO2 nanoparticles (ZA) in water, followed by a specific amount of polyvinyl pyrrolidone (PVP) as spinning add and a minute quantity of surfactant to reduce the surface tension. The new recipe was first electrospun in our lab with a needle type equipment to investigate the influence of solution properties and process parameters. The best recipe was then tested in a wire type semi-pilot equipment to scale-up the production. The ZA/PVP composite nanofibrous membranes produced was calcined to 500oC at a heating rate of 10oC/min, and shrunk to an inorganic mat about half the original size. The needle-type equipment leads to a much stronger mat then the wire-type, while the area density of the inorganic fiber mat was not as important a factor. The inorganic mat was very flexible if the calcination temperature was less than 500oC but became fragile above that. We expected that the working temperature could be extended to 1000oC by replacing the zirconia nanocrystals with that made by YSZ. Unfortunately, the same procedure did not work for YSZ, since the acetic capping was done in an acidic condition where the extraction of yttrium was unavoidable. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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