先前李政憲學長利用靜電紡絲法製備可撓曲的氧化鋯奈米纖維膜，並應用於氣體過濾。通過氯化鈉(0.3µm)粉塵過濾測試，在氣體流速為3.3 cm/s下，過濾效能達到99.986%，壓損為299 Pa。本研究試圖將此製程放大，期望製備更大面積(35 cm x 35 cm)的纖維膜，並拓展其應用。先前使用濃醋酸作為溶劑，基於環保的需求，須將學長使用的濃醋酸溶劑改為水溶劑，將醋酸包覆之氧化鋯奈米粒子(ZA)分散於水中並加入適量PVP高分子，再加入少許界面活性劑以降低表面張力，配製成電紡絲溶膠。我們首先以實驗室中小型針式電紡設備探討溶膠物性及製程條件對於纖維形貌的影響。然後利用業界較大型線式電紡設備嘗試進行製程放大。ZA/PVP溶膠經電紡產生複合纖維膜需要煅燒移除有機物始得到無機纖維膜。此時約有50%面積收縮，不同製程條件所得無機纖維膜面積密度各異。將煅燒後無機纖維膜進行撓曲性測試，探討影響撓曲性因子。發現針式電紡與線式電紡設備所製備之纖維膜，機械強度有明顯差異。另外，為將此纖維膜可承受溫度自500oC提高到1000oC以上，我們也嘗試製備醋酸包覆之釔安定氧化鋯奈米粒子(YZA)，希望依循相同程序製備出煅燒1000oC後依然保有撓曲性之YSZ奈米纖維膜。然而實驗結果在酸性環境下釔會析出，因此並未成功。;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.
