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.

[1] S. Jiang, Y. Chen, G. Duan, C. Mei, A. Greiner, and S. Agarwal, "Electrospun nanofiber reinforced composites: a review," Polymer Chemistry, vol. 9, pp. 2685-2720, 2018.
[2] Z. Li and C. Wang, "Effects of Working Parameters on Electrospinning," One-Dimensional nanostructures: Electrospinning Technique and Unique Nanofibers, Springer, pp. 15-28, 2013.
[3] S. L. Shenoy, W. D. Bates, H. L. Frisch, and G. E. Wnek, "Role of chain entanglements on fiber formation during electrospinning of polymer solutions: good solvent, non-specific polymer–polymer interaction limit," Polymer, vol. 46, pp. 3372-3384, 2005.
[4] C. J. Angammana and S. H. Jayaram, "Analysis of the Effects of Solution Conductivity on Electrospinning Process and Fiber Morphology," IEEE Transactions on Industry Applications, vol. 47, pp. 1109-1117, 2011.
[5] S. Chuangchote, T. Sagawa, and S. Yoshikawa, "Electrospinning of Poly(vinyl pyrrolidone): Effects of Solvents on Electrospinnability for the Fabrication of Poly(p-phenylene vinylene) and TiO2 Nanofibers," Journal of applied polymer science, vol. 114, pp. 2777-2791, 2009.
[6] Q. Yang, Z. Li, Y. Hong, Y. Zhao, S. Qiu, C. Wang, et al., "Influence of solvents on the formation of ultrathin uniform poly(vinyl pyrrolidone) nanofibers with electrospinning," Journal of Polymer Science Part B: Polymer Physics, vol. 42, pp. 3721-3726, 2004.
[7] X. Yuan, Y. Zhang, C. Dong, and J. Sheng, "Morphology of ultrafine polysulfone fibers prepared by electrospinning," Polymer International, vol. 53, pp. 1704-1710, 2004.
[8] H. R. Darrell and C. Iksoo, "Nanometre diameter fibres of polymer, produced by electrospinning," Nanotechnology, vol. 7, p. 216, 1996.
[9] S. H. Tan, R. Inai, M. Kotaki, and S. Ramakrishna, "Systematic parameter study for ultra-fine fiber fabrication via electrospinning process," Polymer, vol. 46, pp. 6128-6134, 2005.
[10] L. Sharifi, F. Assa, H. Ajamein, and S. H. Mirhosseini, "Effect of Voltage and Distance on Synthesis of Boehmite Nanofibers with PVP by the Electrospinning Method," vol. 98, 2017.
[11] S. Farhang Dehghan, F. Golbabaei, B. Maddah, M. Latifi, H. Pezeshk, M. Hasanzadeh, et al., "Optimization of Electrospinning Parameters for PAN-MgO Nanofibers Applied in Air Filtration," Journal of the Air & Waste Management Association, vol. 66, pp. 912-921.2016.
[12] S. Zargham, S. Bazgir, A. Tavakoli, A. Saied Rashidi, and R. Damerchely, "The Effect of Flow Rate on Morphology and Deposition Area of Electrospun Nylon 6 Nanofiber," Journal of Engineered Fabrics & Fibers, vol. 7, 2012.
[13] J. T. McCann, M. Marquez, and Y. Xia, "Highly Porous Fibers by Electrospinning into a Cryogenic Liquid," Journal of the American Chemical Society, vol. 128, pp. 1436-1437, 2006.
[14] P. Kiselev and J. Rosell-Llompart, "Highly aligned electrospun nanofibers by elimination of the whipping motion," Journal of Applied Polymer Science, vol. 125, pp. 2433-2441, 2012.
[15] S. Koombhongse, W. Liu, and D. H. Reneker, "Flat polymer ribbons and other shapes by electrospinning," Journal of Polymer Science Part B: Polymer Physics, vol. 39, pp. 2598-2606, 2001.
[16] J. T. McCann, D. Li, and Y. Xia, "Electrospinning of nanofibers with core-sheath, hollow, or porous structures," Journal of Materials Chemistry, vol. 15, pp. 735-738, 2005.
[17] F.-L. Zhou, R. Gong, and I. Porat, "Mass production of nanofibre assemblies: By electrostatic spinning," Polymer International, vol. 58, pp. 331-342, 2009.
[18] S. Xie and Y. Zeng, "Effects of Electric Field on Multineedle Electrospinning: Experiment and Simulation Study," Industrial & Engineering Chemistry Research, vol. 51, pp. 5336-5345, 2012.
[19] H. Niu and T. Lin, "Fiber Generators in Needleless Electrospinning," Journal of Nanomaterials, vol. 2012, p. 13, 2012.
[20] F. Yalcinkaya, "Preparation of various nanofiber layers using wire electrospinning system," Arabian Journal of Chemistry, 2016.
[21] D. Li and Y. Xia, "Fabrication of Titania Nanofibers by Electrospinning," Nano Letters, vol. 3, pp. 555-560, 2003.
[22] W. Sigmund, J. Yuh, H. Park, V. Maneeratana, G. Pyrgiotakis, A. Daga, et al., "Processing and Structure Relationships in Electrospinning of Ceramic Fiber Systems," Journal of the American Ceramic Society, vol. 89, pp. 395-407, 2006.
[23] Z. Chen, Z. Zhang, C.-C. Tsai, K. Kornev, I. Luzinov, M. Fang, et al., "Electrospun mullite fibers from the sol–gel precursor," Journal of Sol-Gel Science and Technology, vol. 74, pp. 208-219, 2015.
[24] Y. Zhang, J. Li, Q. Li, L. Zhu, X. Liu, X. Zhong, et al., "Preparation of In2O3 ceramic nanofibers by electrospinning and their optical properties," Scripta materialia, vol. 56, pp. 409-412, 2007.
[25] C. Shao, H. Guan, Y. Liu, J. Gong, N. Yu, and X. Yang, "A novel method for making ZrO2 nanofibres via an electrospinning technique," Journal of Crystal Growth, vol. 267, pp. 380-384, 2004.
[26] C. Wessel, R. Ostermann, R. Dersch, and B. M. Smarsly, "Formation of inorganic nanofibers from preformed TiO2 nanoparticles via electrospinning," The Journal of Physical Chemistry C, vol. 115, pp. 362-372, 2010.
[27] H. Zhang and M. Edirisinghe, "Electrospinning zirconia fiber from a suspension," Journal of the American Ceramic Society, vol. 89, pp. 1870-1875, 2006.
[28] M. Möller, N. Tarabanko, C. Wessel, R. Ellinghaus, H. Over, and B. M. Smarsly, "Electrospinning of CeO2 nanoparticle dispersions into mesoporous fibers: on the interplay of stability and activity in the HCl oxidation reaction," RSC Advances, vol. 8, pp. 132-144, 2018.
[29] D. B. Leiser, M. Smith, and H. E. Goldstein, "Developments in fibrous refractory composite insulation," 1981.
[30] Y. Chen, X. Mao, H. Shan, J. Yang, H. Wang, S. Chen, et al., "Free-standing zirconia nanofibrous membranes with robust flexibility for corrosive liquid filtration," RSC Advances, vol. 4, pp. 2756-2763, 2014.
[31] X. Mao, Y. Bai, J. Yu, and B. Ding, "Flexible and highly temperature resistant polynanocrystalline zirconia nanofibrous membranes designed for air filtration," Journal of the American Ceramic Society, vol. 99, pp. 2760-2768, 2016.
[32] M. Guo, B. Ding, X. Li, X. Wang, J. Yu, and M. Wang, "Amphiphobic nanofibrous silica mats with flexible and high-heat-resistant properties," The Journal of Physical Chemistry C, vol. 114, pp. 916-921, 2009.
[33] Y. Wang, W. Li, Y. Xia, X. Jiao, and D. Chen, "Electrospun flexible self-standing γ-alumina fibrous membranes and their potential as high-efficiency fine particulate filtration media," Journal of Materials Chemistry A, vol. 2, pp. 15124-15131, 2014.
[34] S.-J. Park, G. G. Chase, K.-U. Jeong, and H. Y. Kim, "Mechanical properties of titania nanofiber mats fabricated by electrospinning of sol–gel precursor," Journal of sol-gel science and technology, vol. 54, pp. 188-194, 2010.
[35] Y. Si, C. Yan, F. Hong, J. Yu, and B. Ding, "A general strategy for fabricating flexible magnetic silica nanofibrous membranes with multifunctionality," Chemical Communications, vol. 51, pp. 12521-12524, 2015.
[36] A. Biswas, H. Park, and W. M. Sigmund, "Flexible ceramic nanofibermat electrospun from TiO2–SiO2 aqueous sol," Ceramics International, vol. 38, pp. 883-886, 2012.
[37] M. Z. B. Mukhlish, Y. Horie, K. Higashi, A. Ichigi, S. Guo, and T. Nomiyama, "Self-standing conductive ITO-silica nanofiber mats for use in flexible electronics and their application in dye-sensitized solar cells," Ceramics International, vol. 43, pp. 8146-8152, 2017.
[38] H.-y. Wei, H. Li, Y. Cui, R.-l. Sang, H.-y. Wang, P. Wang, et al., "Synthesis of flexible mullite nanofibres by electrospinning based on nonhydrolytic sol–gel method," Journal of Sol-Gel Science and Technology, vol. 82, pp. 718-727, 2017.
[39] X. Mao, H. Shan, J. Song, Y. Bai, J. Yu, and B. Ding, "Brittle-flexible-brittle transition in nanocrystalline zirconia nanofibrous membranes," CrystEngComm, vol. 18, pp. 1139-1146, 2016.
[40] X. Mao, Y. Bai, J. Yu, and B. Ding, "Insights into the flexibility of ZrMxOy (M= Na, Mg, Al) nanofibrous membranes as promising infrared stealth materials," Dalton Transactions, vol. 45, pp. 6660-6666, 2016.
[41] W. Han, B. Ding, M. Park, F. Cui, S.-H. Chae, and H.-Y. Kim, "Insight into the precursor nanofibers on the flexibility of La2O3-ZrO2 nanofibrous membranes," e-Polymers, vol. 17, pp. 243-248, 2017.
[42] G. Cadafalch Gazquez, H. Chen, S. A. Veldhuis, A. Solmaz, C. Mota, B. A. Boukamp, et al., "Flexible yttrium-stabilized zirconia nanofibers offer bioactive cues for osteogenic differentiation of human mesenchymal stromal cells," ACS nano, vol. 10, pp. 5789-5799, 2016.
[43] K. Castkova, K. Maca, J. Sekaninova, J. Nemcovsky, and J. Cihlar, "Electrospinning and thermal treatment of yttria doped zirconia fibres," Ceramics International, vol. 43, pp. 7581-7587, 2017.
[44] M. M. Munir, A. B. Suryamas, F. Iskandar, and K. Okuyama, "Scaling law on particle-to-fiber formation during electrospinning," Polymer, vol. 50, pp. 4935-4943, 2009.
[45] M. Li, Z. Feng, P. Ying, Q. Xin, and C. Li, "Phase transformation in the surface region of zirconia and doped zirconia detected by UV Raman spectroscopy," Physical Chemistry Chemical Physics, vol. 5, pp. 5326-5332, 2003.
[46] F. Ribot, P. Toledano, and C. Sanchez, "X-ray and spectroscopic investigations of the structure of yttrium acetate tetrahydrate," Inorganica chimica acta, vol. 185, pp. 239-245, 1991.
[47] M. Manna, D. Grandstaff, G. Ulmer, and E. Vicenzi, "The chemical durability of yttria-stabilited ZrO2 pH and O2 geothermal sensors," Proceedings of the Tenth International Symposium on Water–Rock Interaction. Balkema, Rotterdam, The Netherlands, pp. 295-299, 2001.
[48] M. Della Negra, C. Knöfel, K. T. S. Thydén, and M. Wandel, "Study of the behaviour of YSZ dispersions in water," 12th Conference of the European Ceramic Society, 2011.
[49] 李政憲，「應用於高溫氣體過濾之氧化鋯奈米纖維濾網」，碩士論文，國立中央大學化學工程與材料工程學系，2016。