本篇論文主要運用霍普金森試驗機在室溫(25℃)下對Nylon 66進行撞擊試驗，並觀測其巨觀機械性質及微觀結構的變化。本次實驗所採用之應變速率分別為2300s-1、3700s-1、5000s-1和6200s-1，並將其細分為高應變速率與低應變速率區間進行討論，再透過所獲得的實驗數據以及微觀結構(OM、SEM)進行分析，藉此了解高應變速率對高分子材料塑變行為及微觀結構之影響。最後利用G'Sell-Jonas 模型為構成方程式來進行模擬，以描述Nylon 66在各應變速率下與塑流應力之關係，方便未來在作為工程模擬分析之用途。
實驗結果指出，應變速率的不同對Nylon 66的機械性質有相當大的影響。在相同應變量下，隨著材料變形的應變速率提升，其塑流應力值、應變速率敏感性係數皆會跟著上升，而熱活化體積、加工硬化率、黏度係數則會隨著應變速率上升而下降。而在相同應變速率下，隨著應變量增加，其熱活化體積會跟著上升，而塑流應力值、應變速率敏感性係數、加工硬化率、黏度係數則會隨著應變量上升而下降。
在微觀結構方面，透過掃描式電子顯微鏡的觀測，Nylon 66在遭受撞擊後會產生凹陷，在凹陷處可以發現許多微裂縫的產生，這些微裂縫便是材料破裂的開端。當試件產生破裂後，可以觀察到破裂邊緣有許多的絲狀物產生，這些絲狀物即是高分子材料在高速撞擊過後產生扭曲的分子結構所形成。

In this study, Nylon 66 was examined under different strain rates by using split-Hopkinson pressure bar to investigate its dynamic deformation behaviors and microstructure characteristics. Impact tests were performed under different strain rates ranging from 2.3×103 s-1 to 6.2×103 s-1 at room temperature.
The results reveal that the mechanical properties are greatly affected by strain rates and the G'Sell-Jonas model can be used to describe the relationship between flow stress and strain. It is found that flow stress and strain rate sensitivity all increase, but the thermal activation volume, work hardening rate and viscosity decreases with the increasing strain rate. However, at a constant strain rate, flow stress, strain rate sensitivity, work hardening rate and viscosity decrease but the thermal activation volume increases with increasing strain. Last but not least, the modified G'Sell-Jonas model is used to describe the deformation behavior of Nylon 66 under the considered strain rate.
Scanning Electron Microscope(SEM) observations show that when Nylon 66 was impacted under high strain rate, the micro-fracture will appear although it can't be observed with the naked eye. Those micro-fracture are the beginning of the fracture, which could cause softening and rapid decrease in the flow stress. SEM fracture morphologies show that there are many threads at the edge of fracture side and the threads' cause of formation is distortion of molecular structure.

[1]M. A. Meyers, Dynamic behavior of materials. John wiley & sons, 1994.
[2]M. E. Hermes, Enough for one lifetime: Wallace carothers, inventor of nylon. Chemical Heritage Foundation, 1996.
[3]H. Kolsky, "An investigation of the mechanical properties of materials at very high rates of loading," Proceedings of the Physical Society. Section B, vol. 62, no. 11, p. 676, 1949.
[4]B. Butcher and C. Karnes, "Strain‐Rate Effects in Metals," Journal of Applied Physics, vol. 37, no. 1, pp. 402-411, 1966.
[5]F. E. Hauser, "Techniques for measuring stress-strain relations at high strain rates," Experimental Mechanics, vol. 6, no. 8, pp. 395-402, 1966.
[6]D. Steinberg, S. Cochran, and M. Guinan, "A constitutive model for metals applicable at high‐strain rate," Journal of Applied Physics, vol. 51, no. 3, pp. 1498-1504, 1980.
[7]G. Halldin and Y. Lo, "Solid‐phase flow behavior of polymers," Polymer Engineering & Science, vol. 25, no. 6, pp. 323-331, 1985.
[8]C. Heffelfinger and P. Schmidt, "Structure and properties of oriented poly (ethylene terephthalate) films," Journal of Applied Polymer Science, vol. 9, no. 8, pp. 2661-2680, 1965.
[9]Y. Tsunekawa, M. Oyane, and K. Kojima, "Effects of irradiation and rolling on the tensile behavior of polyethylene," Journal of Polymer Science Part A: Polymer Chemistry, vol. 50, no. 153, pp. 35-44, 1961.
[10]E. M. Arruda, M. C. Boyce, and R. Jayachandran, "Effects of strain rate, temperature and thermomechanical coupling on the finite strain deformation of glassy polymers," Mechanics of Materials, vol. 19, no. 2-3, pp. 193-212, 1995.
[11]M. C. Boyce, E. Montagut, and A. Argon, "The effects of thermomechanical coupling on the cold drawing process of glassy polymers," Polymer Engineering & Science, vol. 32, no. 16, pp. 1073-1085, 1992.
[12]S. Chou, K. Robertson, and J. Rainey, "The effect of strain rate and heat developed during deformation on the stress-strain curve of plastics," Experimental mechanics, vol. 13, no. 10, pp. 422-432, 1973.
[13]R. Kapoor and S. Nemat-Nasser, "Determination of temperature rise during high strain rate deformation," Mechanics of Materials, vol. 27, no. 1, pp. 1-12, 1998.
[14]D. Rittel, "On the conversion of plastic work to heat during high strain rate deformation of glassy polymers," Mechanics of Materials, vol. 31, no. 2, pp. 131-139, 1999.
[15]D. Rittel, "Experimental investigation of transient thermoelastic effects in dynamic fracture," International Journal of Solids and Structures, vol. 35, no. 22, pp. 2959-2973, 1998.
[16]紀坤宏 and 陳仁浩, "模具內的剪切操作對於 iPP/PC 聚摻物射出成形品的材料結構的影響之研究," 2004.
[17]G. Ungar and X.-b. Zeng, "Learning polymer crystallization with the aid of linear, branched and cyclic model compounds," Chemical reviews, vol. 101, no. 12, pp. 4157-4188, 2001.
[18]R. Janssen, H. Meijer, L. Govaert, R. Schellekens, and B. Schrauwen, Deformation and Failure in Semi-Crystalline Polymer Systems. Citeseer, 2002.
[19]L. H. Sperling, Introduction to physical polymer science. John Wiley & Sons, 2005.
[20]蔡信行, 聚合物化學. 台北: 文京圖書有限公司, 1984.
[21]賴耿陽, 聚丙烯樹脂 PP 原理與應用. 台南: 復漢出版社, 1999.
[22]U. S. Lindholm, "High strain rate tests," Measurement of mechanical properties, vol. 5, no. Part 1, pp. 199-271, 1971.
[23]U. Lindholm and L. Yeakley, "High strain-rate testing: tension and compression," Experimental Mechanics, vol. 8, no. 1, pp. 1-9, 1968.
[24]J. Achenbach, Wave propagation in elastic solids. Elsevier, 2012.
[25]B. Dodd, Adiabatic shear localization: occurrence, theories, and applications. Pergamon Press, 1992.
[26]W.-S. Lee and C.-F. Lin, "Plastic deformation and fracture behaviour of Ti–6Al–4V alloy loaded with high strain rate under various temperatures," Materials Science and Engineering: A, vol. 241, no. 1, pp. 48-59, 1998.
[27]呂名祺, "晶粒尺寸對奈米結構316LVM不銹鋼塑性變形行為及微觀結構特性之效應分析," 2017.
[28]I. M. Ward and D. W. Hadley, An introduction to the mechanical properties of solid polymers. John Wiley & Sons Ltd.; John Wiley & Sons, Inc., 1993.
[29]H. Eyring, "Viscosity, plasticity, and diffusion as examples of absolute reaction rates," The Journal of chemical physics, vol. 4, no. 4, pp. 283-291, 1936.
[30]A. Argon, "A theory for the low-temperature plastic deformation of glassy polymers," Philosophical Magazine, vol. 28, no. 4, pp. 839-865, 1973.
[31]A. S. Argon and M. Bessonov, "Plastic deformation in polyimides, with new implications on the theory of plastic deformation of glassy polymers," Philosophical Magazine, vol. 35, no. 4, pp. 917-933, 1977.
[32]M. C. Boyce, D. M. Parks, and A. S. Argon, "Large inelastic deformation of glassy polymers. Part I: rate dependent constitutive model," Mechanics of Materials, vol. 7, no. 1, pp. 15-33, 1988.
[33]林煌隆, "高分子聚合物在不同應變速率下之壓縮變形特性與破壞分析," 2001.
[34]R. Haward, "The derivation of a strain hardening modulus from true stress-strain curves for thermoplastics," Polymer, vol. 35, no. 18, pp. 3858-3862, 1994.
[35]N. Albérola, P. Mélé, and C. Bas, "Tensile mechanical properties of PEEK films over a wide range of strain rates. II," Journal of applied polymer science, vol. 64, no. 6, pp. 1053-1059, 1997.
[36]C. Bauwens‐Crowet, J. Bauwens, and G. Homes, "Tensile yield‐stress behavior of glassy polymers," Journal of Polymer Science Part B: Polymer Physics, vol. 7, no. 4, pp. 735-742, 1969.
[37]Y. Duan, A. Saigal, R. Greif, and M. Zimmerman, "A uniform phenomenological constitutive model for glassy and semicrystalline polymers," Polymer Engineering & Science, vol. 41, no. 8, pp. 1322-1328, 2001.
[38]C. G'sell and J. Jonas, "Determination of the plastic behaviour of solid polymers at constant true strain rate," Journal of materials science, vol. 14, no. 3, pp. 583-591, 1979.
[39]V. Tan, X. Zeng, and V. Shim, "Characterization and constitutive modeling of aramid fibers at high strain rates," International Journal of Impact Engineering, vol. 35, no. 11, pp. 1303-1313, 2008.
[40]N. S. Al-Maliky, "Strain rate behaviour of thermoplastic polymers," © Noori Sabih Jarrih Al-Maliky, 1997.
[41]U. Andrade, M. Meyers, and A. Chokshi, "Constitutive description of work-and shock-hardened copper," Scripta metallurgica et materialia, vol. 30, no. 7, pp. 933-938, 1994.
[42]S. Esmaeili, L. Cheng, A. Deschamps, D. Lloyd, and W. Poole, "The deformation behaviour of AA6111 as a function of temperature and precipitation state," Materials Science and Engineering: A, vol. 319, pp. 461-465, 2001.
[43]B. Viguier, "Dislocation densities and strain hardening rate in some intermetallic compounds," Materials Science and Engineering: A, vol. 349, no. 1, pp. 132-135, 2003.
[44]D. Chu and J. Morris, "The influence of microstructure on work hardening in aluminum," Acta materialia, vol. 44, no. 7, pp. 2599-2610, 1996.
[45]I. Ward, "The role of molecular networks and thermally activated processes in the deformation behavior of polymers," Polymer Engineering & Science, vol. 24, no. 10, pp. 724-736, 1984.
[46]J. Lefebvre and B. Escaig, "Plastic deformation of glassy amorphous polymers: influence of strain rate," Journal of materials science, vol. 20, no. 2, pp. 438-448, 1985.
[47]J. Cavrot, J. Haussy, J. Lefebvre, and B. Escaig, "Thermally activated deformation of glassy polystyrene," Materials Science and Engineering, vol. 36, no. 1, pp. 95-103, 1978.
[48]J. Campbell and W. Ferguson, "The temperature and strain-rate dependence of the shear strength of mild steel," Philosophical Magazine, vol. 21, no. 169, pp. 63-82, 1970.
[49]D. Zaukelies, "Observation of slip in nylon 66 and 610 and its interpretation in terms of a new model," Journal of applied physics, vol. 33, no. 9, pp. 2797-2803, 1962.
[50]G. Fanchini and D. Gagliostro, "The e-st@ r CubeSat: Antennas system," Acta Astronautica, vol. 69, no. 11-12, pp. 1089-1095, 2011.
[51]曾昫嵐, "霍普金森桿應用於材料動態測試之模擬與分析," 1998.
[52]R. Woodward, G. Egglestone, B. Baxter, and K. Challis, "Resistance to penetration and compression of fibre-reinforced composite materials," Composites Engineering, vol. 4, no. 3, pp. 329-341, 1994.