本研究使用尼龍4,6/甲酸溶液進行單根針電紡製備尼龍4,6奈米纖維，並討論溶液性質對電紡纖維形態的影響。溶液導電度與表面張力隨溶液濃度增加幾乎沒有改變；以溶液比黏度對體積分率作圖，因聚電解質效應entanglement濃度出現在1 wt%，但當濃度高於10 wt%才能電紡得到均勻纖維。並且隨濃度上升電紡得到的纖維直徑增加，不同濃度電紡得到的纖維平均直徑約介於50~200 nm。

使用同軸雙管針頭，以4 wt% 尼龍6/甲酸為內管流體，15 wt% 尼龍4,6/甲酸為外管流體進行同軸電紡製備尼龍6/尼龍4,6芯鞘纖維；並固定外管流量(Qs)改變內管流量(Qc)的方式進行同軸電紡，可收集得到外直徑介於105~120 nm的奈米纖維。

將芯鞘纖維以DSC在25~260 oC間以10 oC/min進行動態升降溫，發現在降溫過程尼龍6於芯鞘纖維中的結晶峰出現於210 oC，相較於尼龍 6 cast film的降溫結晶峰出現於190 oC提升了20 oC。並且由Qc越小所收集的芯鞘纖維中，尼龍6的結晶度也會降低。以FT-IR分析尼龍6於芯鞘纖維中降溫結晶形成的晶型為a結構。

By using the coaxial electrospinning technique the Nylon 6/Nylon 4,6 core/shell fibers can be produced, and the melt-crystallization of Nylon 6 in the fiber core region was studied. 4 wt% Nylon 6/formic acid and 15 wt% Nylon 4,6/formic acid solutions were delivered to the inner and outer channel of coaxial spinneret for electrospinning to prepare Nylon 6/Nylon 4,6 core/shell fibers. By fixing the flow rate of outer channel (Qs) and changing the flow rate of the inner channel (Qc), uniform fibers with average diameter about 105~120 nm were obtained. And we use the differential scanning calorimetry with a rate 10 oC/min to heat the fibers to 260 oC, and then cool it back to 25 oC to observe the melt-recrystallization behavior of Nylon 6 in the core/shell fibers. We found out that the peak temperature of melt-recrystallization was 210 oC, which is 20 oC higher than that we measured from Nylon 6 cast film of 190 oC. And the crystallinity of Nylon 6 decreased with the Qc used in electrospinning process decreased. By using Fouier transform infrared spectroscopy, we also found out that the melt-recrystallization crystal of Nylon 6 in the core/shell fibers was a form crystal.

[1] 鄒世雍, "以電紡絲法製備尼龍奈米纖維及其微結構鑑定", 國立成
功大學碩士論文 (2007).
[2] F. Auriemma, V. Petraccone, L. Parravicini, P. Corradini, "Mesomorphic Form (β) of Nylon 6", Macromolecules 30, 7554 (1997).
[3] K. Miyashaka, K. Makishima, "Transition of Nylon 6 g-Phase Crystals by Stretching in the Chain Direction", Journal of Polymer Science: partA-1 5, 3017 (1967).
[4] K. Kaji, I. Sakurada, "Crystallite Size Determination of Nylon 6 by Wallner's Method", Journal of Polymer Science: Polymer Physics Edition 12, 1491 (1974).
[5] T. D. Fornes, D. R. Paul, "Crystallization behavior of nylon 6 nanocomposites", Polymer 44, 3945 (2003).
[6] Y. Li, W. A. Gorddard III, "Nylon 6 Crystal Structures, Folds, and Lamellae from Theory", Macromolecules 35, 8440 (2002).
[7] C. Ramesh, E. B. Gowd, "High-Temperature X-ray Diffraction Studies on the Crystalline Transitions in the α- and γ-Forms of Nylon-6", Macromolecules 34, 3308 (2001).
[8] E. D. T. Atkins, M. Hill, S. K. Hong, A. Keller, S. Organ, "Lamellar structure and morphology of nylon 46 crystals: a new chain folding mechanism for nylons", Macromolecules 25, 917 (1992).
[9] N. A. Jones, E. D. T. Atkins, M. J. Hill, S. J. Cooper, L. Franco, "Polyamides with a Choice of Structure and Crystal Surface Chemistry. Studies of Chain-Folded Lamellae of Nylons 8 10 and 10 12 and Comparison with the Other 2N 2(N + 1) Nylons 4 6 and 6 8", Macromolecules 30, 3569 (1997).
[10] Q. Zhang, Z. Zhang, H. Zhang, Z. Mo, "Isothermal and nonisothermal crystallization kinetics of nylon-46", Journal of Polymer Science Part B: Polymer Physics 40, 1784 (2002).
[11] C. Ramesh, "New Crystalline Transitions in Nylons 4,6, 6,10, and 6,12 Using High Temperature X-ray Diffraction Studies", Macromolecules 32, 3721 (1999).
[12] J. Zeleny, "The Electrical Discharge from Liquid Points, and a Hydrostatic Method of Measuring the Electric Intensity at Their Surfaces", Physical Review 3, 69 (1914).
[13] F. Anton, "Process and apparatus for preparing artificial threads", United States Patent (1934).
[14] D. H. Reneker, I. Chun, "Nanometre diameter fibres of polymer, produced by electrospinning", Nanotechnology 7, 216 (1996).
[15] I. Chun, D. H. Reneker, H. Fong, "Beaded nanofibers formed during electrospinning", Polymer 40, 4585 (1999).
[16] G. Taylor, "Disintegration of Water Drops in an Electric Field", Proceedings of the Royal Society of London. Series A, Mathematical and Sciences 280, 383 (1964).
[17] M. Claupeaua, B. Prunet-Focha, "Electrostatic spraying of liquids in cone-jet mode", Journal of Electrostatics 22, 135 (1989).
[18] A. Barrero, A. M. Gañán-Calvo, J. Dávila, A. Palacio, E. Gómez-González, "Low and high Reynolds number flows inside Taylor cones", Physical Review E 58, 7309 (1998).
[19] J. Doshi, "Electrospinning Process and Applications of Electrospun Fibers", Industry Applications Society Annual Meeting 3, 1698 (1994).
[20] D. Galehouse, D. H. Reneker, H. Xu, "Study of the relationship between jet diameter and interference color during electrospinning", Polymer Materials: Science & Engineering 88, (2003).
[21] Y. M. Shin, M. M. Hohman, M. P. Brenner, G. C. Rutledge, "Experimental characterization of electrospinning: the electrically forced jet and instabilities", Polymer 42, 09955 (2001).
[22] P. K. Baumgarten, "Electrostatic spinning of acrylic microfibers", Journal of Colloid and Interface Science 36, 71 (1971).
[23] A. L. Yarin, S. Koombhongse, D. H. Reneker, "Bending instability in electrospinning of nanofibers", Journal of Applied Physics 89, 3018 (2001).
[24] W. Liu, D. H. Reneker, S. Koombhongse, "Flat Polymer Ribbons and Other Shapes by Electrospinning", Journal of Polymer Science Part B: Polymer Physics 39, 2598 (2001).
[25] K.-H. Lee, K.-W. Kim, A. Pesapane, H.-Y. Kim, J. F. Rabolt, "Polarized FT-IR Study of Macroscopically Oriented Electrospun Nylon-6 Nanofibers", Macromolecules 41, 1494 (2008).
[26] Y. Liu, L. Cui, F. Guan, Y. Gao, N. E. Hedin, L. Zhu, H. Fong, "Crystalline Morphology and Polymorphic Phase Transitions in Electrospun Nylon-6 Nanofibers", Macromolecules 40, 6283 (2007).
[27] M. M. Bergshoef, G. J. Vancso, "Transparent nanocomposites with ultrathin, electrospun nylon‐4, 6 fiber reinforcement", Advanced Materials 11, 1362 (1999).
[28] H. Chaobo, C. Shuiliang, L. Chuilin, H. R. Darrell , Q. Haiyan, Y. Ying, H. Haoqing, "Electrospun polymer nanofibres with small diameters", Nanotechnology 17, 1558 (2006).
[29] B. De Schoenmaker, L. Van der Schueren, Ö. Ceylan, K. De Clerck, "Electrospun polyamide 4.6 nanofibrous nonwovens: parameter study and characterization", Journal of Nanomaterials 2012, 14 (2012).
[30] Z. Sun, E. Zussman, A. L. Yarin, J. H. Wendorff, A. Greiner, "Compound Core–Shell Polymer Nanofibers by Co-Electrospinning", Advanced Materials 15, 1929 (2003).
[31] D. Li, J. T. McCann, Y. Xia, "Use of Electrospinning to Directly Fabricate Hollow Nanofibers with Functionalized Inner and Outer Surfaces", Small 1, 83 (2005).
[32] M. Wang, J. H. Yu, D. L. Kaplan, G. C. Rutledge, "Production of Submicron Diameter Silk Fibers under Benign Processing Conditions by Two-Fluid Electrospinning", Macromolecules 39, 1102 (2006).
[33] I. G. Loscertales, A. Barrero, I. Guerrero, R. Cortijo, M. Marquez, A. M. Gañán-Calvo, "Micro/Nano Encapsulation via Electrified Coaxial Liquid Jets", Science 295, 1695 (2002).
[34] D. Li, Y. Xia, "Direct Fabrication of Composite and Ceramic Hollow Nanofibers by Electrospinning", Nano Letters 4, 933 (2004).
[35] J. T. McCann, D. Li, Y. Xia, "Electrospinning of nanofibers with core-sheath, hollow, or porous structures", Journal of Materials Chemistry 15, 735 (2005).
[36] Y. Z. Zhang, X. Wang, Y. Feng, J. Li, C. T. Lim, S. Ramakrishna, "Coaxial Electrospinning of (Fluorescein Isothiocyanate-Conjugated Bovine Serum Albumin)-Encapsulated Poly(ε-caprolactone) Nanofibers for Sustained Release", Biomacromolecules 7, 1049 (2006).
[37] D.-G. Yu, C. J. Branford-White, N. P. Chatterton, K. White, L.-M. Zhu, X.-X. Shen, W. Nie, "Electrospinning of Concentrated Polymer Solutions", Macromolecules 43, 10743 (2010).
[38] H. Luo, Y. Huang, D. Wang, J. Shi, "Coaxial-electrospinning as a new method to study confined crystallization of polymer", Journal of Polymer Science Part B: Polymer Physics 51, 376 (2013).
[39] J. R. Schaefgen, C. F. Trivisonno, "Polyelectrolyte Behavior of Polyamides. I. Viscosities of Solutions of Linear Polyamides in Formic Acid and in Sulfuric Acid1", Journal of the American Chemical Society 73, 4580 (1951).
[40] S.-Y. Tsou, H.-S. Lin, C. Wang, "Studies on the electrospun Nylon 6 nanofibers from polyelectrolyte solutions: 1. Effects of solution concentration and temperature", Polymer 52, 3127 (2011).
[41] R. Gaymans, T. Van Utteren, J. Van den Berg, J. Schuyer, "Preparation and some properties of nylon 46", Journal of Polymer Science: Polymer Chemistry Edition 15, 537 (1977).
[42] Z. Zhang, K. Huang, Z. Liu, "Synthesis of high molecular weight nylon 46 in supercritical carbon dioxide", Macromolecules 44, 820 (2011).
[43] P. Cong, F. Xiang, X. Liu, T. Li, "Morphology and microstructure of polyamide 46 wear debris and transfer film: In relation to wear mechanisms", Wear 265, 1100 (2008).
[44] F. Liberti, B. Wunderlich, "Melting of polycaprolactam", Journal of Polymer Science Part A‐2: Polymer Physics 6, 833-848 (1968).
[45] B. Guo, Q. Zou, Y. Lei, M. Du, M. Liu, D. Jia, "Crystallization behavior of polyamide 6/halloysite nanotubes nanocomposites", Thermochimica Acta 484, 48-56 (2009).