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研究生： 曾子娟
Tzu-Jian - Tseng
論文名稱： 以二氧化碳批次發泡不同軟段多元醇組成熱塑性聚氨酯之研究
Foaming of thermoplastic polyurethanes composed with different soft segments using CO2 as the blowing agent
指導教授： 葉樹開
Shu-Kai Yeh
口試委員: 胡孝光
Shiaw-Guang Hu
朱建嘉
Chien-Chia Chu
學位類別： 碩士
Master
系所名稱： 工程學院 - 材料科學與工程系
Department of Materials Science and Engineering
論文出版年： 2017
畢業學年度： 105
語文別： 中文
論文頁數： 106
中文關鍵詞： 熱塑性聚氨酯 、多元醇 、二氧化碳 、批次發泡 、微米泡 、泡材密度
外文關鍵詞： Thermoplastic polyurethane, polyol, carbon dioxide, batch foam, microcellulars foam, foam density
相關次數： 點閱：262  下載：12 
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    • 熱塑性聚氨酯(TPU)為嵌段線性高分子，結構分為軟鏈段及硬鏈段。TPU的性質與組成有關。不同的軟硬鏈段組成使TPU具有不同的物理性質。而現今TPU在市場上最有發展潛力的材料應用即為ETPU (expandable TPU)，具有高抗衝擊性與耐磨耗性、高回彈性及低密度(0.2~0.3 g/cm3)，本實驗嘗試以不同的軟鏈段製備低密度TPU泡材。
    本實驗第一部份以預聚物法自行合成TPU。我們以MDI及BD當作硬段及擴鏈劑，並使用PPG、PTMEG、PBA分別作為軟段組成。實驗結果發現PPG基之TPU具有最低的硬度70A及最低的楊氏模數、PTMEG基之TPU硬度為85A且具有最高的斷裂伸長率，而PBA基之TPU具有最高的硬度90A，最高的楊氏模數及最低的斷裂伸長率。
    第二部份以二氧化碳對TPU分別進行一步及二步批次發泡，在一步發泡中討論含浸溫度對於泡孔型態的影響，隨著含浸溫度上升(60-120°C)，泡材密度可降至0.3 g/cm3。然而，在未添加成核劑之TPU發泡材料，泡體中間會有明顯裂縫且泡材外觀不平整，因此添加滑石粉作為成核劑，實驗結果發現確實有改善裂縫的情況並使泡材更加光滑。而在二次發泡中討論發泡時間及發泡溫度的影響，二步發泡法可以進一步降低泡材的密度，結果顯示在發泡時間為60秒時隨發泡溫度上升(60-100°C)，泡材密度可降至0.27 g/cm3。一步法發泡與二步法發泡在相同的發泡溫度下，在二步法中以長時間發泡，容易具有更低的泡材密度。
    從二步法的實驗結果也發現，在發泡時間為30秒時泡孔密度達到最高值，超過30秒以後泡孔密度趨近於常數而泡孔大小逐漸增大，此時發泡的型態轉以泡孔成長為主。

    Thermoplastic polyurethanes (TPU) are linear segmented block copolymers composed of soft and hard segments. It is known that the properties of TPU are related to its constituents. Different soft segments and hard segments offer different physical properties. Among the various applications, expandable TPU (ETPU) has become the most attractive application. ETPU provides excellent impact and wear resistance, high resilience, high tear strength and low density (0.2 ~ 0.3 g/cm3). This study will focus on how to prepare microcellular TPU foam with low foam density.
    The TPU was synthesized by the prepolymer method without solvent. The most commonly used 4, 4’-methylene bis(phenyl isocyanate) (MDI) and 1,4-butanediol (BD) system were applied as the hard segment. Poly (propylene glycol) (PPG), poly (tetramethylene ether) glycol (PTMEG), and poly (1,4-butylene adipate) (PBA) were used as the soft segments. The PPG-based TPU has the lowest hardness of 70A and the lowest Young's modulus. The PTEMG-based TPU has the hardness of 85A and the highest elongation at break. The PBA-based TPU has the hardness of 90A, the highest Young's modulus and the lowest elongation at break.
    The synthesized TPUs were foamed by one-step and two-step batch foaming and using CO2 as the blowing agent. In the one-step foaming experiment, with the increase of the saturation temperature from 60 to 120°C the foam density decreased 0.3 g/cm3. It was found that most TPU foams had cracks or cleavages in the TPU foams and the surface of the TPU foams was rough. Adding talc as the nucleation agent could improve the cell structure and the surface of TPU foams.
    In the two-step foaming experiments, the effects of foaming time to the cell morphology was discussed. The foam density can be manipulated by the foaming time. When the foaming time increased to 60 sec, the foam density decreased to 0.27 g/cm3 as the foaming temperature increased from 60 to 100°C. Under the same foaming conditions, two-step foaming had a lower foam density compared with one-step foaming.
    In the two step foaming experiments, it was found that the cell density reached the maximum value at the foaming time of 30 seconds. After 30 seconds, the cell density approached to a constant, but the cell size increased with the foaming time. The decrease in foaming density after 30 seconds of foaming results from the cell growth.

    摘要 i Abstract iii 誌謝 v 目錄 vi 圖目錄 ix 表目錄 xiii 第一章 緒論 1 1.1 前言 1 第二章 相關理論與文獻回顧 4 2.1 熱塑性聚氨酯(Thermoplastic Polyurethane)簡介 4 2.1.1 TPU的合成 6 2.1.2 TPU的原料 7 2.2 滑石粉 10 2.3 高分子發泡材料 11 2.3.1 發泡劑 12 2.3.2 發泡機制 13 2.3.3 批次發泡 17 第三章　實驗方法 19 3.1 實驗藥品 19 3.2 實驗儀器 24 3.3 實驗步驟 27 3.3.1 實驗流程圖 27 3.3.2 不同軟段之熱塑性聚氨酯製備 28 3.3.3 官能基滴定實驗 28 3.3.4 混煉加工 29 3.3.5 滑石粉/熱塑性聚氨酯複合材料之製備 30 3.3.6 射出成型除泡 30 3.3.7 批次發泡 30 3.4 量測方法 32 3.4.1 高效能高分子核心系統(APC) 32 3.4.2 熱示差掃描量熱儀(DSC) 32 3.4.3 熱重損失分析儀(TGA) 32 3.4.4 熱機械分析儀(TMA)32 3.4.5 硬度量測 33 3.4.6 拉伸測試 33 3.4.7 掃描式電子顯微鏡(SEM) 34 3.4.8 泡孔孔徑(cell size)計算 34 3.4.9 泡材密度(foam density)量測 34 3.4.10 泡孔密度(cell density)計算 35 3.4.11 溶解度量測 35 第四章　結果與討論 37 4.1 不同軟段多元醇之熱塑性聚氨酯(TPU)性質分析 37 4.1.1預聚物滴定分析 37 4.1.2 分子量量測 37 4.1.3 熱分析 39 4.1.4 硬度量測 42 4.1.5 拉伸測試 42 4.1.6 密度量測 43 4.1.7 二氧化碳溶解度量測 43 4.2 不同軟段多元醇之熱塑性聚氨酯(TPU)之一步法批次發泡分析 44 4.2.1 含浸溫度對泡孔型態之影響 44 4.2.3 添加滑石粉對泡孔型態之影響 51 4.3 不同軟段多元醇之熱塑性聚氨酯(TPU)之二步法批次發泡分析 58 4.3.1 二步發泡發泡時間對於泡孔型態之影響 58 4.3.2 發泡動力學定性探討 67 4.3.3 二步發泡發泡溫度對於泡孔型態之影響 69 4.3.4 二步法及一步法發泡的比較 72 第五章　結論 75 參考文獻 77 附錄 A 不同軟段組成之TPU之溶解度量測 87 附錄 B 未添加滑石粉一次發泡SEM圖 88 附錄 C 添加滑石粉一次發泡SEM圖 92 附錄 D PPG組成之TPU在20°C發泡SEM圖 96 附錄 E 二步發泡發泡溫度80°C不同發泡時間SEM圖 98 附錄 F 二步發泡發泡時間15~60秒、發泡溫度60-100°C之泡材密度 102 附錄 G 空氣置換膨脹倍率收縮比較 103 附錄 H PPG基TPU在20°C 2000psi含浸24小時二次發泡SEM圖 104

    1. Chan, E., et al., Novel Thermally Conductive Thermoplastic/Ceramic Composite Foams. Macromolecular Materials and Engineering, 2012. 297(10): p. 1014-1020.
    2. Leung, S.N., et al., Ideal surface geometries of nucleating agents to enhance cell nucleation in polymeric foaming processes. Journal of Applied Polymer Science, 2008. 108(6): p. 3997-4003.
    3. Sorrentino, L., M. Aurilia, and S. Iannace, Polymeric foams from high-performance thermoplastics. Advances in Polymer Technology, 2011. 30(3): p. 234-243.
    4. Wang, C. and S. Ying, Solid-state foaming of carbon fiber/polypropylene/nano-CaCO3 composite using supercritical CO2. Polymer Composites, 2014. 35(9): p. 1723-1735.
    5. Park, C.B., D.F. Baldwin, and N.P. Suh, Effect of the pressure drop rate on cell nucleation in continuous processing of microcellular polymers. Polymer Engineering & Science, 1995. 35(5): p. 432-440.
    6. Matsunaga, K., et al., Gas permeability of thermoplastic polyurethane elastomers. Polymer Journal, 2005. 37(6): p. 413-417.
    7. Ito, S., et al., Generation of microcellular polyurethane with supercritical carbon dioxide. Journal of Applied Polymer Science, 2007. 106(6): p. 3581-3586.
    8. Infinergy® (E-TPU) -The first expanded TPU. Available from: http://www.plasticsportal.net/wa/plasticsEU/portal/show/common/content/campaigns/infinergy/english/pdf/infinergy.pdf.
    9. Prasad, A., G. Fotou, and S. Li, The effect of polymer hardness, pore size, and porosity on the performance of thermoplastic polyurethane-based chemical mechanical polishing pads. Journal of Materials Research, 2013. 28(17): p. 2380-2393.
    10. Mi, H.-Y., et al., Fabrication of thermoplastic polyurethane tissue engineering scaffold by combining microcellular injection molding and particle leaching. Journal of Materials Research, 2014. 29(08): p. 911-922.
    11. Song, J.J., H.H. Chang, and H.E. Naguib, Design and characterization of biocompatible shape memory polymer (SMP) blend foams with a dynamic porous structure. Polymer, 2015. 56: p. 82-92.
    12. 劉宇哲, 超臨界二氧化碳發泡製備法奈米孔徑之熱塑性聚氨酯奈米複合材料研究, 化學工程研究所. 2012, 國立臺北科技大學: 台北市. p. 105.
    13. 彭昇平, 以超臨界二氧化碳發泡技術製備熱塑性聚氨酯微米泡材, 化學工程研究所. 2014, 國立臺北科技大學: 台北市. p. 125.
    14. 康庭瑋, 高分子硬度對超臨界二氧化碳發泡技術製備熱塑性聚氨酯微奈米孔洞泡材之影響, 化學工程與生物科技系化學工程碩士班. 國立臺北科技大學: 台北市.
    15. 陳瀅如, 以超臨界二氧化碳發泡製備石墨烯/熱塑性聚氨酯之微奈米孔洞發泡材料, 化學工程研究所. 2015, 國立臺北科技大學: 台北市.
    16. Prissok, F. and F. Braun, Foams based on thermoplastic polyurethanes. 2010, US20100222442.
    17. Raps, D., et al., Past and present developments in polymer bead foams and bead foaming technology. Polymer, 2015. 56: p. 5-19.
    18. Urbanczyk, L., et al., Batch foaming of SAN/clay nanocomposites with scCO2: A very tunable way of controlling the cellular morphology. Polymer, 2010. 51(15): p. 3520-3531.
    19. Prisacariu, C., Polyurethane Elastomers: From Morphology to Mechanical Aspects. 2011: Springer Vienna.
    20. Engels, H.W., et al., Polyurethanes: versatile materials and sustainable problem solvers for today's challenges. Angew Chem Int Ed Engl, 2013. 52(36): p. 9422-41.
    21. Uhlig, K., Discovering Polyurethanes. 1999: Hanser Publishers.
    22. Kojio, K., S. Nakashima, and M. Furukawa, Microphase-separated structure and mechanical properties of norbornane diisocyanate-based polyurethanes. Polymer, 2007. 48(4): p. 997-1004.
    23. Furukawa, M., et al., Microphase-separated structure and mechanical properties of novel polyurethane elastomers prepared with ether based diisocyanate. Polymer, 2005. 46(24): p. 10817-10822.
    24. Krol, P., Synthesis methods, chemical structures and phase structures of linear polyurethanes. Properties and applications of linear polyurethanes in polyurethane elastomers, copolymers and ionomers. Progress in Materials Science, 2007. 52(6): p. 915-1015.
    25. Drobny, J.G., Thermoplastic Polyurethane Elastomers. 2014: p. 233-253.
    26. Yilgör, I., E. Yilgör, and G.L. Wilkes, Critical parameters in designing segmented polyurethanes and their effect on morphology and properties: A comprehensive review. Polymer, 2015. 58: p. A1-A36.
    27. 山西省化工研究所, 聚氨酯彈性體手册. 2001, 北京: 化學工業出版社.
    28. Kim, K.-J. and J. White, Dispersion of Agglomerated Nanoparticles in Rubber Processing, in Polymer Nanocomposites Handbook. 2009, CRC Press.
    29. Zhao, G., T. Wang, and Q. Wang, Studies on wettability, mechanical and tribological properties of the polyurethane composites filled with talc. Applied Surface Science, 2012. 258(8): p. 3557-3564.
    30. Talc in Plastics. Available from: http://www.mondominerals.com/uploads/media/mondo_bulletin_plastics.pdf.
    31. Xanthos, M., Functional Fillers for Plastics. 2010: Wiley.
    32. Yousfi, M., et al., Use of new synthetic talc as reinforcing nanofillers for polypropylene and polyamide 6 systems: thermal and mechanical properties. J Colloid Interface Sci, 2013. 403: p. 29-42.
    33. Drobny, J.G., Handbook of thermoplastic elastomers. 2014, Merrimack, New Hampshire and Prague, Czech Republic: Elsevier Science. 17-32.
    34. Subramanian, M.N., Types of Additives, in Plastics Additives and Testing. 2013, John Wiley & Sons, Inc. p. 35-72.
    35. Notario, B., J. Pinto, and M.A. Rodriguez-Perez, Nanoporous polymeric materials: A new class of materials with enhanced properties. Progress in Materials Science, 2016. 78-79: p. 93-139.
    36. Wang, G.-l., et al., Research on formation mechanisms and control of external and inner bubble morphology in microcellular injection molding. Polymer Engineering & Science, 2015. 55(4): p. 807-835.
    37. Aram, E. and S. Mehdipour-Ataei, A review on the micro- and nanoporous polymeric foams: Preparation and properties. International Journal of Polymeric Materials and Polymeric Biomaterials, 2015. 65(7): p. 358-375.
    38. Mittal, V., Polymer Nanocomposite Foams. 2013: CRC Press.
    39. Goel, S.K. and E.J. Beckman, Generation of microcellular polymeric foams using supercritical carbon dioxide. I: Effect of pressure and temperature on nucleation. Polymer Engineering & Science, 1994. 34(14): p. 1137-1147.
    40. Martini-Vvedensky, J.E., N.P. Suh, and F.A. Waldman, Microcellular closed cell foams and their method of manufacture. 1984, US 4473665 A.
    41. Jacobs, L.J.M., M.F. Kemmere, and J.T.F. Keurentjes, Sustainable polymer foaming using high pressure carbon dioxide: a review on fundamentals, processes and applications. Green Chemistry, 2008. 10(7): p. 731.
    42. Jacobs, M.A., M.F. Kemmere, and J.T.F. Keurentjes, Foam processing of poly(ethylene-co-vinyl acetate) rubber using supercritical carbon dioxide. Polymer, 2004. 45(22): p. 7539-7547.
    43. 劉士榮, 高分子加工. 2010, 台中.
    44. Shukla, S. and K.W. Koelling, Steady flow simulation of a polymer-diluent solution through an abrupt axisymmetric contraction using internally consistent rheological scaling. Journal of Applied Polymer Science, 2007. 106(2): p. 1053-1074.
    45. Wong, A., et al., The synergy of supercritical CO2 and supercritical N2 in foaming of polystyrene for cell nucleation. The Journal of Supercritical Fluids, 2014. 90: p. 35-43.
    46. Secretariat, O., The Montreal protocol on substances that deplete the ozone layer, United Nations Environment Programme. 2000: Nairobi, Kenya.
    47. Xu, Z.-M., et al., Foaming of polypropylene with supercritical carbon dioxide. The Journal of Supercritical Fluids, 2007. 41(2): p. 299-310.
    48. Colton, J.S. and N.P. Suh, The nucleation of microcellular thermoplastic foam with additives: Part I: Theoretical considerations. Polymer Engineering & Science, 1987. 27(7): p. 485-492.
    49. Colton, J.S. and N.P. Suh, The nucleation of microcellular thermoplastic foam with additives: Part II: Experimental results and discussion. Polymer Engineering & Science, 1987. 27(7): p. 493-499.
    50. Colton, J.S. and N.P. Suh, Nucleation of microcellular foam: Theory and practice. Polymer Engineering & Science, 1987. 27(7): p. 500-503.
    51. Okolieocha, C., et al., Microcellular to nanocellular polymer foams: Progress (2004–2015) and future directions – A review. European Polymer Journal, 2015. 73: p. 500-519.
    52. Goel, S.K. and E.J. Beckman, Generation of microcellular polymeric foams using supercritical carbon dioxide. II: Cell growth and skin formation. Polymer Engineering & Science, 1994. 34(14): p. 1148-1156.
    53. Sun, X., et al., Investigation on the cell nucleation and cell growth in microcellular foaming by means of temperature quenching. Journal of Applied Polymer Science, 2004. 93(1): p. 163-171.
    54. Leung, S.N., et al., Computer simulation of bubble-growth phenomena in foaming. Industrial and Engineering Chemistry Research, 2006. 45(23): p. 7823-7831.
    55. Costeux, S., et al., Experimental study and modeling of nanofoams formation from single phase acrylic copolymers. Journal of Cellular Plastics, 2014. 51(2): p. 197-221.
    56. Tsivintzelis, I., A.G. Angelopoulou, and C. Panayiotou, Foaming of polymers with supercritical CO2: An experimental and theoretical study. Polymer, 2007. 48(20): p. 5928-5939.
    57. Mi, H.-Y., et al., Approach to Fabricating Thermoplastic Polyurethane Blends and Foams with Tunable Properties by Twin-Screw Extrusion and Microcellular Injection Molding. Advances in Polymer Technology, 2014. 33(1): p. 21380.
    58. White, L.J., et al., The effect of processing variables on morphological and mechanical properties of supercritical CO2 foamed scaffolds for tissue engineering. Acta Biomater, 2012. 8(1): p. 61-71.
    59. Matuana, L.M., C.B. Park, and J.J. Balatinecz, Processing and cell morphology relationships for microcellular foamed PVC/wood-fiber composites. Polymer Engineering and Science, 1997. 37(7): p. 1137-1147.
    60. Naguib, H.E., C.B. Park, and N. Reichelt, Fundamental foaming mechanisms governing the volume expansion of extruded polypropylene foams. Journal of Applied Polymer Science, 2004. 91(4): p. 2661-2668.
    61. Frerich, S.C., Biopolymer foaming with supercritical CO2—Thermodynamics, foaming behaviour and mechanical characteristics. The Journal of Supercritical Fluids, 2015. 96: p. 349-358.
    62. Costeux, S., CO2-blown nanocellular foams. Journal of Applied Polymer Science, 2014. 131(23): p. 41293.
    63. Kiran, E., Supercritical fluids and polymers – The year in review – 2014. The Journal of Supercritical Fluids, 2016. 110: p. 126-153.
    64. Product Data Sheet Jetfine1H/1CH. Available from: http://www.imerystalc.com/.
    65. Moore, J.C., Gel permeation chromatography. I. A new method for molecular weight distribution of high polymers. Journal of Polymer Science Part A: General Papers, 1964. 2(2): p. 835-843.
    66. Trathnigg, B., Determination of MWD and chemical composition of polymers by chromatographic techniques. Progress in Polymer Science, 1995. 20(4): p. 615-650.
    67. Pattanayak, A., CLAY-TETHERED THERMOPLASTIC POLYURETHANE NANOCOMPOSITES BY BULK POLYMERIZATION METHODS. 2005, University of Akron.
    68. Jung, C., SYNTHESIS OF THERMOPLASTIC POLYURETHANES AND POLYURETHANE NANOCOMPOSITES UNDER CHAOTIC MIXING CONDITIONS. 2005, University of Akron.
    69. Chu, C.-C., et al., Preparation of microporous thermoplastic polyurethane by low-temperature supercritical CO2 foaming. Journal of Cellular Plastics, 2016.
    70. Leung, S.N., et al., Mechanism of extensional stress-induced cell formation in polymeric foaming processes with the presence of nucleating agents. The Journal of Supercritical Fluids, 2012. 63: p. 187-198.
    71. Lee, L., et al., Polymer nanocomposite foams. Composites Science and Technology, 2005. 65(15-16): p. 2344-2363.
    72. Marrazzo, C., E. Di Maio, and S. Iannace, Conventional and nanometric nucleating agents in poly(ε-caprolactone) foaming: Crystals vs. bubbles nucleation. Polymer Engineering and Science, 2008. 48(2): p. 336-344.
    73. Abouzahr, S., G.L. Wilkes, and Z. Ophir, Structure-property behaviour of segmented polyether-MDI-butanediol based urethanes: effect of composition ratio. Polymer, 1982. 23(7): p. 1077-1086.
    74. Tien, Y.I. and K.H. Wei, Thermal transitions of montmorillonite/polyurethane nanocomposites. Journal of Polymer Research, 2000. 7(4): p. 245-250.
    75. THERMAL APPLICATIONS NOTE-Enhanced DSC Glass Transition Measurements. Available from: http://www.tainstruments.com/pdf/literature/TN7.pdf
    76. Bagdi, K., et al., Quantitative estimation of the strength of specific interactions in polyurethane elastomers, and their effect on structure and properties. European Polymer Journal, 2012. 48(11): p. 1854-1865.
    77. Wen-hao Zhang, et al., Preparation and Microcellular Foaming Investigation of Poly (Lactic Acid) Talc Composites, Antec 2013. 2013: Cincinnati, Ohio, U.S.A.
    78. Xiao, H., D. Guo, and J. Bao, Synergistic effects of N, N'-bis (benzoyl) sebacic acid dihydrazide and talc on the physical and mechanical behaviors of poly(l -latic acid). Journal of Applied Polymer Science, 2015. 132(7).
    79. 李俊賢, 塑料工業手冊 : 聚氨酯. 1999, 北京: 化學工業出版社.
    80. Bagdi, K., et al., Specific interactions, structure and properties in segmented polyurethane elastomers. Express Polymer Letters, 2011. 5(5): p. 417-427.
    81. Yeh, S.K., et al., Thermoplastic polyurethane/clay nanocomposite foam made by batch foaming. Journal of Cellular Plastics, 2013. 49(2): p. 119-130.
    82. Hossieny, N.J., et al., Crystallization of hard segment domains with the presence of butane for microcellular thermoplastic polyurethane foams. Polymer, 2014. 55(2): p. 651-662.
    83. Liao, X., et al., The effects of viscoelastic properties on the cellular morphology of silicone rubber foams generated by supercritical carbon dioxide. RSC Adv., 2015. 5(129): p. 106981-106988.
    84. Taki, K., et al., CO2 foaming of poly(ethylene glycol)/polystyrene blends: Relationship of the blend morphology, CO2 mass transfer, and cellular structure. Journal of Applied Polymer Science, 2005. 97(5): p. 1899-1906.
    85. Zhang, P., N. Zhou, and B. Li, Effects of Process Variables on Microcellular Structure and Crystallization of Polypropylene Foams with Supercritical CO2 as the Foaming Agent—A Study of Microcellular Foaming of Polypropylene. Polymer-Plastics Technology and Engineering, 2007. 46(9): p. 885-891.
    86. Ding, J., W. Ma, and Q. Zhong, Foaming of Homogeneous Polypropylene and Ethylene-Polypropylene Block Copolymer Using Supercritical Carbon Dioxide. Polymer-Plastics Technology and Engineering, 2013. 52(6): p. 592-598.
    87. Spitael, P., C.W. Macosko, and R.B. McClurg, Block copolymer micelles for nucleation of microcellular thermoplastic foams. Macromolecules, 2004. 37(18): p. 6874-6882.
    88. Callister, W.D. and D.G. Rethwisch, Materials Science and Engineering: An Introduction. 2010: John Wiley & Sons.
    89. Ruiz, J.A.R., et al., Two-step micro cellular foaming of amorphous polymers in supercritical CO2. The Journal of Supercritical Fluids, 2011. 57(1): p. 87-94.
    90. Reverchon, E. and S. Cardea, Production of controlled polymeric foams by supercritical CO2. The Journal of Supercritical Fluids, 2007. 40(1): p. 144-152.
    91. Taki, K., et al., Visual observation of CO2 foaming of polypropylene-clay nanocomposites. Polymer Engineering and Science, 2004. 44(6): p. 1004-1011.
    92. Bledzki, A.K. and O. Faruk, Injection moulded microcellular wood fibre-polypropylene composites. Composites Part A: Applied Science and Manufacturing, 2006. 37(9): p. 1358-1367.
    93. Wang, C., et al., Numerical investigation of nucleating-agent-enhanced heterogeneous nucleation. Industrial and Engineering Chemistry Research, 2010. 49(24): p. 12783-12792.
    94. Leung, S.N., C.B. Park, and H. Li, Numerical simulation of polymeric foaming processes using modified nucleation theory. Plastics, Rubber and Composites, 2006. 35(3): p. 93-100.

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