本研究主要利用電紡絲技術製備具有可撓性之氧化鋯奈米纖維網並應用於高溫氣體之過濾。我們使用之起始物為表面醋酸改質之氧化鋯奈米粒子(ZA)所形成透明水性溶膠。並藉由醋酸與水之添加調整溶液之導電度與表面張力，透過ZA與聚乙烯吡咯烷酮(PVP)濃度調整溶液黏度，同時將無機物與有機物之體積比控制在30/70以上。在適當之極化電場及溶液流速下可製備出平滑沒有珠狀結構的連續纖維。經過乾燥後只要以500°C鍛燒就可將有機物移除。因為不產生大幅度晶相轉變與燒結，所以氧化鋯纖維膜保有其可撓性並且可承受400次以上180°彎折。但是由於我們未添加氧化釔，所以在800°C高溫鍛燒後會有晶相轉變及體積收縮而變脆弱。經過不同鍛燒溫度下測試，確定可撓性與XRD晶相變化有直接關係。最後我們透過電紡參數的調整製備出不同直徑之奈米纖維且厚度適當之可撓性濾材，進行氯化鈉粉塵之過濾測試，找出過濾效率最高而壓損較低的適當濾材製備方法。

Electrospinning is a scalable process for the preparation of flexible zirconia nanofibrous web useful as a hot gas filter. Composite fibers are formed under polarized electric field from a solution containing zirconium salt and a hydrophilic polymer (PVP) and are later transformed into zirconia via calcination. In this study, the precursor employed was a transparent aqueous sol of zirconia nanocrystals modified with acetate ligand. The surface tension and the conductivity of the precursor were adjusted by the addition of acetic acid and water. The viscosity and the inorganic/organic ratio were adjusted by the concentration of ZA and PVP. Under proper operation conditions, smooth fibrous web without bead structure could be electrospun. The zirconia mat obtained remained flexibility after calcination at 500°C and withstood 400 times of 180° bending. This temperature is lower than that required by literature processes using amorphous precursor. Consequently, the problem of fiber fracture due to crystallization was eliminated. Upon increasing the calcination temperature and duration, the monoclinic phase started to appear which break the fiber and remove its flexibility due to volume expansion. We further prepared flexible mats with nanofibers of different diameters, and study the filtration of NaCl dust. Our mat could achieve more than 99.9% removal with less than 200 Pa pressure drop at 20 LPM flow rate.

1. T. Grafe, K. Graham, paper presented at the International Nonwovens Technical Conference, Georgia, 2002.
2. T. H. Grafe, K. M. Graham, paper presented at the Nonwovens in Filtration - Fifth International Conference, Germany, 2003.
3. K. Graham, M. Ouyang, T. G. Tom Raether, B. McDonald, P. Knauf, paper presented at the Fifteenth Annual Technical Conference & Expo of the American Filtration & Separations Society, Galveston, Texas, 2002.
4. N. Tucker, J. J. Stanger, M. P. Staiger, H. Razzaq, K. Hofman, The History of the Science and Technology of Electrospinning from 1600 to 1995. Journal of Engineered Fibers and Fabrics, 63-73 (2012).
5. M. L. F. Nascimento, E. S. Araújo, E. R. Cordeiro, A. H. P. d. Oliveira, H. P. d. Oliveira, A Literature Investigation about Electrospinning and Nanofibers: Historical Trends, Current Status and Future Challenges. Recent Patents on Nanotechnology 9, 76-85 (2015).
6. A. L. Szentivanyi, H. Zernetsch, H. Menzel, B. Glasmacher, A review of developments in electrospinning technology: new opportunities for the design of artificial tissue structures. Int J Artif Organs 34, 986-997 (2011).
7. K. Garg, G. L. Bowlin, Electrospinning jets and nanofibrous structures. Biomicrofluidics 5, 13403 (2011).
8. D. H. Reneker, A. L. Yarin, H. Fong, S. Koombhongse, Bending instability of electrically charged liquid jets of polymer solutions in electrospinning. Journal of Applied Physics 87, 4531-4547 (2000).
9. A. K. Haghi, M. Akbari, Trends in electrospinning of natural nanofibers. physica status solidi (a) 204, 1830-1834 (2007).
10. Q. Yang 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 42, 3721-3726 (2004).
11. J.-Y. Zheng et al., The Effect of Surfactants on the Diameter and Morphology of Electrospun Ultrafine Nanofiber. Journal of Nanomaterials 2014, 1-9 (2014).
12. Z. Li, C. Wang, Effects of Working Parameters on Electrospinning. 15-28 (2013).
13. H. Fong, I. Chun, D. H. Reneker, Beaded nanofibers formed during electrospinning. Polymer 40, 4585-4592 (1999).
14. S. Huan et al., Effect of Experimental Parameters on Morphological, Mechanical and Hydrophobic Properties of Electrospun Polystyrene Fibers. Materials 8, 2718-2734 (2015).
15. J. Lyons, C. Li, F. Ko, Melt-electrospinning part I: processing parameters and geometric properties. Polymer 45, 7597-7603 (2004).
16. S. A. Theron, E. Zussman, A. L. Yarin, Experimental investigation of the governing parameters in the electrospinning of polymer solutions. Polymer 45, 2017-2030 (2004).
17. K. Arayanarakul, N. Choktaweesap, D. Aht-ong, C. Meechaisue, P. Supaphol, Effects of Poly(ethylene glycol), Inorganic Salt, Sodium Dodecyl Sulfate, and Solvent System on Electrospinning of Poly(ethylene oxide). Macromolecular Materials and Engineering 291, 581-591 (2006).
18. C. Mit-uppatham, M. Nithitanakul, P. Supaphol, Ultrafine Electrospun Polyamide-6 Fibers: Effect of Solution Conditions on Morphology and Average Fiber Diameter. Macromolecular Chemistry and Physics 205, 2327-2338 (2004).
19. T. Uyar, F. Besenbacher, Electrospinning of uniform polystyrene fibers: The effect of solvent conductivity. polymer 49, 5336-5343 (2008).
20. C. Huang et al., Electrospun polymer nanofibres with small diameters. Nanotechnology 17, 1558-1563 (2006).
21. W. Ding et al., Manipulated Electrospun PVA Nanofibers with Inexpensive Salts. Macromolecular Materials and Engineering 295, 958-965 (2010).
22. J. Y. Park, I. H. Lee, G. N. Bea, Optimization of the electrospinning conditions for preparation of nanofibers from polyvinylacetate (PVAc) in ethanol solvent. Journal of Industrial and Engineering Chemistry 14, 707-713 (2008).
23. T. Mazoochi, M. Hamadanian, M. Ahmadi, V. Jabbari, Investigation on the morphological characteristics of nanofiberous membrane as electrospun in the different processing parameters. International Journal of Industrial Chemistry 3, 2 (2012).
24. D. H. Reneker, A. L. Yarin, Electrospinning jets and polymer nanofibers. Polymer 49, 2387-2425 (2008).
25. V. Pillay et al., A Review of the Effect of Processing Variables on the Fabrication of Electrospun Nanofibers for Drug Delivery Applications. Journal of Nanomaterials 2013, 1-22 (2013).
26. M. Guo et al., Amphiphobic Nanofibrous Silica Mats with Flexible and High-Heat-Resistant Properties. J. Phys. Chem. 114, 916-921 (2010).
27. X. Mao et al., Silica nanofibrous membranes with robust flexibility and thermal stability for high-efficiency fine particulate filtration. RSC Advances 2, 12216 (2012).
28. S.-J. Park, G. G. Chase, K.-U. Jeong, H. Y. Kim, Mechanical properties of titania nanofiber mats fabricated by electrospinning of sol–gel precursor. Journal of Sol-Gel Science and Technology 54, 188-194 (2010).
29. E. T. Bender, P. Katta, G. G. Chase, R. D. Ramsier, Spectroscopic investigation of the composition of electrospun titania nanofibers. Surface and Interface Analysis 38, 1252-1256 (2006).
30. R. Zhang et al., In situ synthesis of flexible hierarchical TiO2nanofibrous membranes with enhanced photocatalytic activity. J. Mater. Chem. A 3, 22136-22144 (2015).
31. A. Biswas, H. Park, W. M. Sigmund, Flexible ceramic nanofibermat electrospun from TiO2–SiO2 aqueous sol. Ceramics International 38, 883-886 (2012).
32. M. Xi et al., Mechanically flexible hybrid mat consisting of TiO2 and SiO2 nanofibers electrospun via dual spinnerets for photo-detector. Materials Letters 120, 219-223 (2014).
33. C. Shao et al., A novel method for making ZrO2 nanofibres via an electrospinning technique. Journal of Crystal Growth 267, 380-384 (2004).
34. H. B. Zhang, M. J. Edirisinghe, Electrospinning Zirconia Fiber From a Suspension. Journal of the American Ceramic Society 89, 1870-1875 (2006).
35. E. Davies, A. Lowe, M. Sterns, K. Fujihara, S. Ramakrishna, Phase Morphology in Electrospun Zirconia Microfibers. Journal of the American Ceramic Society 91, 1115-1120 (2008).
36. L. Li, P. Zhang, J. Liang, S. M. Guo, Phase transformation and morphological evolution of electrospun zirconia nanofibers during thermal annealing. Ceramics International 36, 589-594 (2010).
37. Y. Zhao, Y. Tang, Y. Guo, X. Bao, Studies of electrospinning process of zirconia nanofibers. Fibers and Polymers 11, 1119-1122 (2010).
38. L. Yin, J. Niu, Z. Shen, Y. Bao, S. Ding, Preparation and photocatalytic activity of nanoporous zirconia electrospun fiber mats. Materials Letters 65, 3131-3133 (2011).
39. D. Qin, A. Gu, G. Liang, L. Yuan, A facile method to prepare zirconia electrospun fibers with different morphologies and their novel composites based on cyanate ester resin. RSC Adv. 2, 1364-1372 (2012).
40. R. Ghelich, R. Mehdinavaz Aghdam, F. S. Torknik, M. R. Jahannama, Low Temperature Carbothermal Reduction Synthesis of ZrC Nanofibers via Cyclized Electrospun PVP/Zr(OPr)4Hybrid. International Journal of Applied Ceramic Technology 13, 352-358 (2016).
41. O. Saligheh, R. Khajavi, M. E. Yazdanshenas, A. Rashidi, Production and Characterization of Zirconia (ZrO2) Ceramic Nanofibers by Using Electrospun Poly(Vinyl Alcohol)/Zirconium Acetate Nanofibers as a Precursor. Journal of Macromolecular Science, Part B 55, 605-616 (2016).
42. V. V. Rodaev, A. O. Zhigachev, V. V. Korenkov, Y. I. Golovin, The influence of zirconia precursor/binding polymer mass ratio in the intermediate electrospun composite fibers on the phase transformation of final zirconia nanofibers. physica status solidi (a) 213, 2352-2355 (2016).
43. R. C. Garvie, The Occurrence of Metastable Tetragonal Zirconia as a Crystallite Size Effect. J. Phys. Chem. 69, 1238–1243 (1965).
44. A.-M. Azad, T. Matthews, J. Swary, Processing and characterization of electrospun Y2O3-stabilized ZrO2 (YSZ) and Gd2O3-doped CeO2 (GDC) nanofibers. Materials Science and Engineering: B 123, 252-258 (2005).
45. J. Y. Li et al., Hollow fibers of yttria-stabilized zirconia (8YSZ) prepared by calcination of electrospun composite fibers. Materials Letters 62, 2396-2399 (2008).
46. Y. Chen et al., Free-standing zirconia nanofibrous membranes with robust flexibility for corrosive liquid filtration. RSC Adv. 4, 2756-2763 (2014).
47. G.-X. Sun, F.-T. Liu, J.-Q. Bi, C.-A. Wang, Electrospun zirconia nanofibers and corresponding formation mechanism study. Journal of Alloys and Compounds 649, 788-792 (2015).
48. X. Mao, Y. Bai, J. Yu, B. Ding, J. Ferreira, Flexible and Highly Temperature Resistant Polynanocrystalline Zirconia Nanofibrous Membranes Designed for Air Filtration. Journal of the American Ceramic Society 99, 2760-2768 (2016).
49. X. Mao et al., Brittle-flexible-brittle transition in nanocrystalline zirconia nanofibrous membranes. CrystEngComm 18, 1139-1146 (2016).
50. K. Castkova, K. Maca, J. Sekaninova, J. Nemcovsky, J. Cihlar, Electrospinning and thermal treatment of yttria doped zirconia fibres. Ceramics International 43, 7581-7587 (2017).
51. J. Li, X. Jiao, D. Chen, Preparation of Zirconia Fibers via a Simple Aqueous Sol‐Gel Method. Journal of Dispersion Science and Technology 28, 531-535 (2007).
52. 白謹通, 製備具再分散之立方體奈米氧化鋯結晶粒子. 化學工程與材料工程學系, 國立中央大學 (2012).
53. E. M. Kock, M. Kogler, T. Bielz, B. Klotzer, S. Penner, In Situ FT-IR Spectroscopic Study of CO2 and CO Adsorption on Y2O3, ZrO2, and Yttria-Stabilized ZrO2. J Phys Chem C Nanomater Interfaces 117, 17666-17673 (2013).