近年來高分子發泡材料因環保與節能的議題受到全球重視，其絕熱與輕量化的特性不僅可以節省能源，還可以減少塑膠的用量，因此如何提高泡孔密度、減小泡孔尺寸並且提升泡孔均勻性得到高品質的泡材就成為了許多學者研究的重點。
過去大部分的研究僅能透過掃描式電子顯微鏡(Scanning Electron Microscope, SEM)對實驗完成後的最終發泡樣品進行結構分析，無法直接了解發泡過程。為了觀察發泡過程初期的來龍去脈本研究將建立批次發泡視覺化機台並透過實驗驗證機台的可行性， 再利用批次發泡機台針對熱塑性聚氨酯(Thermoplastic polyurethane, TPU)發泡過程的初期進行觀察分析。觀察並比較三種TPU 在不同溫度條件下的發泡過程，分別為混煉前、混煉後以及添加成核劑，而實驗溫度為120°C、130℃、140℃以及150℃。目前已成功拍攝到發泡過程的影片，研究觀察到實驗溫度越高泡體成核出現提早的趨勢，還有泡體尺寸越大、泡體密度越小；另外添加成核劑後的TPU 在泡體成核有明顯提早的情形。

Polymer foams have gained global attention in recent years due to environmental
and energy-saving concerns. Their excellent insulation and lightweight properties help
save energy and reduce the amount of plastic used. Therefore, many scholars have
focused their research on increasing cell density, reducing cell size, and improving cell uniformity to obtain high-quality foam materials.
In the past, most studies could only analyze the structure of the final foamed
samples using a Scanning Electron Microscope (SEM) after understanding the foaming
process. In order to observe the intricacies of the early stages of the foaming process, this study aims to establish a batch foaming visualization system and verify that it will be used to observe and analyze the initial stages of the foaming process of thermoplastic polyurethane (TPU). Three types of TPU will be observed and compared under different temperature conditions; before compounding, after compounding, and with
the addition of a nucleating agent. The experimental temperatures will be set at 120℃,
130℃, 140℃ and 150℃.
Currently, videos capturing the foaming process have been successfully recorded.
The study observed that as the experimental temperature increased, there was a trend
of earlier cell nucleation, with larger cell sizes and lower cell densities. Additionally, the TPU samples with the addition of a nucleating agent showed significant early
nucleation of cells.

1. Polymer Foam Market Outlook - 2027. 2020; Available from: https://www.alliedmarketresearch.com/polymer-foam-market.
2. Polymer Foam Market: Global Industry Analysis and Forecast (2023-2029). 2022; Available from: https://www.maximizemarketresearch.com/market-report/global-polymer-foam-market/33278/#details.
3. D.I. Collias, and D.G. Baird, Impact behavior of microcellular foams of polystyrene and styrene-acrylonitrile copolymer, and single-edge-notched tensile toughness of microcellular foams of polystyrene, styrene-acrylonitrile copolymer, and palycarbonate. Polymer Engineering and Science, 1995. 35(14): p. 1178-1183.
4. D.I. Collias, D.G. Baird, and R.J.M. Borggreve, Impact toughening of polycarbonate by microcellular foaming. Polymer, 1994. 35(18): p. 3978-3983.
5. K.A. Seeler, and V. Kumar, Tension-tension fatigue of microcellular polycarbonate: initial results. Journal of Reinforced Plastics and Composites, 1993. 12(3): p. 359-376.
6. S. Doroudiani, C.B. Park, and M.T. Kortschot, Processing and characterization of microcellular foamed high-density polyethylene/isotactic polypropylene blends. Polymer Engineering and Science, 1998. 38(7): p. 1205-1215.
7. L.M. Matuana, C.B. Park, and J.J. Bauvhnecz, Cell morphology and property relationships of microcellular foamed PVC/wood-fiber composites. Polymer Engineering and Science, 1998. 38(11): p. 1862-1872.
8. K. Taki, T. Nakayama, T. Yatsuzuka and M. Ohshima, Visual observations of batch and continuous foaming processes. Journal of Cellular Plastics, 2003. 39(2): p. 155-169.
9. V. Shaayegan, L. H. Mark, A. Tabatabaei and C.B. Park, A new insight into foaming mechanisms in injection molding via a novel visualization mold. Express Polymer Letters, 2016. 10(6): p. 462-469.
10. Q. Guo, J. Wang, C.B. Park and M. Ohshima, A microcellular foaming simulation system with a high pressure-drop rate. Industrial and Engineering Chemistry Research, 2006. 45(18): p. 6153-6161.
11. P.C. Lee, J. Wang, and C.B. Park, Extruded open-cell foams using two semicrystalline polymers with different crystallization temperatures. Industrial and Engineering Chemistry Research, 2006. 45(1): p. 175-181.
12. M. Tomin, and Á. Kmetty, Polymer foams as advanced energy absorbing materials for sports applications—A review. Journal of Applied Polymer Science, 2022. 139(9): p. 51714.
13. C. Okolieocha, D. Raps, K. Subramaniam and V. Altstädt, Microcellular to nanocellular polymer foams: Progress (2004–2015) and future directions – A review. European Polymer Journal, 2015. 73: p. 500-519.
14. R. Dugad, G. Radhakrishna, and A. Gandhi, Recent advancements in manufacturing technologies of microcellular polymers: a review. Journal of Polymer Research, 2020. 27(7): p. 182.
15. A.K. Bledzki, and O. Faruk, Extrusion and injection moulded microcellular wood fibre reinforced polypropylene composites. Cellular Polymers, 2004. 23(4): p. 211-227.
16. C.D. Han, Y.W. Kim, and K.D. Malhotra, A study of foam extrusion using a chemical blowing agent. Journal of Applied Polymer Science, 1976. 20(6): p. 1583-1595.
17. United National Environment Programme Ozone Secretariat, Handbook for the Montreal Protocol. 2019.
18. E. Aram, 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.
19. A. Wong, H. Guo, V. Kumar, C.B. Park and N. P. Suh, Microcellular Plastics. Encyclopedia of Polymer Science and Technology, 2016: p. 1-57.
20. A. Wong, L. H. Mark, M. M. Hasan and C. B. Park, The synergy of supercritical CO2 and supercritical N2 in foaming of polystyrene for cell nucleation. Journal of Supercritical Fluids, 2014. 90: p. 35-43.
21. A. Wong, Y. Guo, C.B. Park and N.Q. Zhou, A polymer visualization system with accurate heating and cooling control and high-speed imaging. International Journal of Molecular Sciences, 2015. 16(5): p. 9196-9216.
22. J.S. Colton, and N.P. Suh, The nucleation of microcellular thermoplastic foam with additives: Part I: Theoretical considerations. Polymer Engineering and Science, 1987. 27(7): p. 485-492.
23. J.H. Han, and C.D. Han, Bubble nucleation in polymeric liquids. II. theoretical considerations. Journal of Polymer Science Part B: Polymer Physics, 1990. 28(5): p. 743-761.
24. S.N. Leung, A. Wong, C.B. Park and J.H. Zong, 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.
25. S.N. Leung, C.B. Park, and H. Li, Effects of nucleating agents shapes and interfacial properties on cell nucleation. Journal of Cellular Plastics, 2010. 46(5): p. 441-460.
26. S.N. Leung, 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.
27. H.J. Yoo, and C.D. Han, Studies on structural foam processing. III. Bubble dynamics in foam extrusion through a converging die. Polymer Engineering and Science, 1981. 21(2): p. 69-75.
28. C.D. Han, and H.J. Yoo, Studies on structural foam processing. IV. Bubble growth during mold filling. Polymer Engineering and Science, 1981. 21(9): p. 518-533.
29. M. Amon, and C.D. Denson, A study of the dynamics of foam growth: Analysis of the growth of closely spaced spherical bubbles. Polymer Engineering and Science, 1984. 24(13): p. 1026-1034.
30. P. Payvar, , Mass transfer-controlled bubble growth during rapid decompression of a liquid. International Journal of Heat and Mass Transfer, 1987. 30(4): p. 699-706.
31. A. Arefmanesh, S.G. Advani, and E.E. Michaelides, A Numerical Study of Bubble-Growth during Low-Pressure Structural Foam Molding Process. Polymer Engineering and Science, 1990. 30(20): p. 1330-1337.
32. M.A.Shafi, J.G. Lee, and R.W. Flumerfelt, Prediction of cellular structure in free expansion polymer foam processing. Polymer Engineering and Science, 1996. 36(14): p. 1950-1959.
33. K. Taki, and Y. Otsuki, (15) マクロスコピック系の CAE : 発泡成形の基礎と応用. Seikei-Kakou, 2006. 18(3): p. 205-218.
34. R. Pop-Iliev, F. Liu, G. Liu and C.B. Park, Rotational foam molding of polypropylene with control of melt strength. Advances in Polymer Technology, 2003. 22(4): p. 280-296.
35. H.E. Naguib, 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.
36. A.H. Behravesh, C.B. Park, L.K. Cheung and R.D. Venter, Extrusion of polypropylene foams with hydrocerol and isopentane. Journal of Vinyl and Additive Technology, 1996. 2(4): p. 349-357.
37. T.A.Osswald, and G. Menges, Material science of polymers for engineers. 3rd edition 2012, Cincinnati, OH, Hanser Publishers.
38. P.L. Durrill, and R.G. Griskey, Diffusion and solution of gases into thermally softened or molten polymers: Part II. Relation of diffusivities and solubilities with temperature pressure and structural characteristics. AIChE Journal, 1969. 15(1): p. 106-110.
39. P.L. Durrill, and R.G. Griskey, Diffusion and solution of gases in thermally softened or molten polymers: Part I. Development of technique and determination of data. AIChE Journal, 1966. 12(6): p. 1147-1151.
40. J. Crank, , The mathematics of diffusion. 2nd edition 1975, Oxford, UK, Clarendon Press. p.51
41. S. N. Leung, C. B. Park, D. Xu, H. Li and R. G. Fenton, Computer simulation of bubble-growth phenomena in foaming. Industrial and Engineering Chemistry Research, 2006. 45(23): p. 7823-7831.
42. M. Mar Bernal, Effect of carbon nanofillers on flexible polyurethane foaming from a chemical and physical perspective. RSC Advances, 2014. 4(40): p. 20761-20768.
43. S. Pardo-Alonso, E. Solórzano, S. Estravís, M.A. Rodríguez-Pérez, J.A. De Saja, In situ evidence of the nanoparticle nucleating effect in polyurethane-nanoclay foamed systems. Soft Matter, 2012. 8(44): p. 11262-11270.
44. S. Pardo-Alonso, E. Solórzano, L. Brabant, P. Vanderniepen, M. Dieick, L. Van Hoorebeke, M.A. Rodríguez-Pérez, 3D Analysis of the progressive modification of the cellular architecture in polyurethane nanocomposite foams via X-ray microtomography. European Polymer Journal, 2013. 49(5): p. 999-1006.
45. S. Pardo-Alonso, E. Solórzano, and M.A. Rodríguez-Pérez, Time-resolved X-ray imaging of nanofiller-polyurethane reactive foam systems. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2013. 438: p. 119-125.
46. E. Solórzano, S. Pardo-Alonso, J.A. De Saja, M.A. Rodríguez-Pérez, X-ray radioscopy in-situ studies in thermoplastic polymer foams. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2013. 438: p. 167-173.
47. E. Solórzano, S. Pardo-Alonso, N. Kardijlov, I. Manke, F. Wieder, F. García-Moreno, M.A. Rodríguez-Pérez, Comparison between neutron tomography and X-ray tomography: A study on polymer foams. Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms, 2014. 324: p. 29-34.
48. S. Pérez-Tamarit, E. Solórzano, R. Mokso, M.A. Rodríguez-Pérez, In-situ understanding of pore nucleation and growth in polyurethane foams by using real-time synchrotron X-ray tomography. Polymer, 2019. 166: p. 50-54.
49. E. Brown, and H.M. Jaeger, Shear thickening in concentrated suspensions: phenomenology, mechanisms and relations to jamming. Reports on Progress in Physics, 2014. 77(4): p. 23.
50. K. Taki, T. Yanagimoto, E. Funami, M. Okamoto, M. Oshima, Visual observation of CO2 foaming of polypropylene-clay nanocomposites. Polymer Engineering and Science, 2004. 44(6): p. 1004-1011.
51. Q.P. Guo, J. Wang, and C.B. Park, A Comparison of CO2 and N2 Foaming Behaviors of PP in a Visualization System. International Polymer Processing, 2020. 35(5): p. 503-517.
52. A. Wong, S.N. Leung, G.Y.G. Li, C.B. Park, Role of processing temperature in polystyrene and polycarbonate foaming with carbon dioxide. Industrial and Engineering Chemistry Research, 2007. 46(22): p. 7107-7116.
53. Q. Guo, Y. Mei, S.S.Y. Chang, J. Wang, C.B. Park, Cell nucleation and growth study of PP foaming with CO2 in a batch-simulation system. SAE Technical Papers, 2006.
54. C.D. Han, and C.A. Villamizar, Studies on structural foam processing I. The rheology of foam extrusion. Polymer Engineering and Science, 1978. 18(9): p. 687-698.
55. Tatibouët, J. and R. Gendron, A Study of Strain-Induced Nucleation in Thermoplastic Foam Extrusion. Journal of Cellular Plastics, 2004. 40(1): p. 27-44.
56. A. Wong, R.K.M. Chu, S.N. Leung, C.B. Park, J.H. Zong, A batch foaming visualization system with extensional stress-inducing ability. Chemical Engineering Science, 2011. 66(1): p. 55-63.
57. A.Wong, and C.B. Park, A visualization system for observing plastic foaming processes under shear stress. Polymer Testing, 2012. 31(3): p. 417-424.
58. A.Wong, and C.B. Park, The effects of extensional stresses on the foamability of polystyrene-talc composites blown with carbon dioxide. Chemical Engineering Science, 2012. 75: p. 49-62.
59. C.A.Villamizar, and C.D. Han, Studies on structural foam processing II. Bubble dynamics in foam injection molding. Polymer Engineering and Science, 1978. 18(9): p. 699-710.
60. V.Shaayegan, G. Wang, and C.B. Park, Study of the bubble nucleation and growth mechanisms in high-pressure foam injection molding through in-situ visualization. European Polymer Journal, 2016. 76: p. 2-13.
61. V. Shaayegan, G. Wang, and C.B. Park, Effect of foam processing parameters on bubble nucleation and growth dynamics in high-pressure foam injection molding. Chemical Engineering Science, 2016. 155: p. 27-37.
62. V. Shaayegan, L.H. Mark, C.B. Park, G. Wang, Identification of cell-nucleation mechanism in foam injection molding with gas-counter pressure via mold visualization. AIChE Journal, 2016. 62(11): p. 4035-4046.
63. V. Shaayegan, C. Wang, F. Costa, S. Han, C.B. Park, Effect of the melt compressibility and the pressure drop rate on the cell-nucleation behavior in foam injection molding with mold opening. European Polymer Journal, 2017. 92: p. 314-325.
64. N.J. Hossieny, M.R. Barzegari, M. Nofar, S.H. Mahmood, C.B. Park, Crystallization of hard segment domains with the presence of butane for microcellular thermoplastic polyurethane foams. Polymer, 2014. 55(2): p. 651-662.
65. 徐廷豪, 以超臨界二氧化碳技術探討不同硬度熱塑性聚氨酯之發泡行為,碩士論文,國立臺灣科技大學,材料科學與工程研究所.2019.
66. R.H. Hansen, and W.M. Martin, Novel Methods for the Production of Foamed Polymers. Nucleation of Dissolved Gas by Localized Hot Spots. Industrial and Engineering Chemistry Product Research and Development, 1964. 3(2): p. 137-141.
67. R.H. Hansen, and W.M. Martin, Novel methods for the production of foamed polymers ii. nucleation of dissolved gas by finely-divided metals. Journal of Polymer Science Part B: Polymer Letters, 1965. 3(4): p. 325-330.
68. R. Li, J.H. Lee, C. Wang, L.H. Mark, C.B. Park, Solubility and diffusivity of CO2 and N2 in TPU and their effects on cell nucleation in batch foaming. The Journal of Supercritical Fluids, 2019. 154: p 104623.
69. S.K. Yeh, R. Rangappa, T.H. Hsu, S. Utomo, Effect of extrusion on the foaming behavior of thermoplastic polyurethane with different hard segments. Journal of Polymer Research, 2021. 28(7): p. 244.
70. V. Kumar, and N.P. Suh, A process for making microcellular thermoplastic parts. Polymer Engineering and Science, 1990. 30(20): p. 1323-1329.
71. Q. Guo, Visualization of polymer foaming using a batch foaming simulation system with a high pressure-drop rate., Ph.D. Dissertation, Department of Mechanical and Insdustrial Engineering, University of Toronto, 2007
72. S.N. Leung, A. Wong, C.B. Park, Q. Guo, Strategies to estimate the pressure drop threshold of nucleation for polystyrene foam with carbon dioxide. Industrial and Engineering Chemistry Research, 2009. 48(4): p. 1921-1927.
73. C.B. Park, D.F. Baldwin, and N.P. Suh, Effect of the pressure drop rate on cell nucleation in continuous processing of microcellular polymers. Polymer Engineering and Science, 1995. 35(5): p. 432-440.
74. X.M. Han, K.W. Koelling, D.L. Tomasko, L.J. Lee, Continuous microcellular polystyrene foam extrusion with supercritical CO2. Polymer Engineering and Science, 2002. 42(11): p. 2094-2106.
75. H. Guo, A. Nicolae, and V. Kumar, Solid-state poly(methyl methacrylate) (PMMA) nanofoams. Part II: Low-temperature solid-state process space using CO2 and the resulting morphologies. Polymer, 2015. 70: p. 231-241.
76. C. Barlow, V. Kumar, B. Flinn, R.K. Bordia, J. Weller, Impact strength of high density solid-state microcellular polycarbonate foams. Journal of Engineering Materials and Technology-Transactions of the Asme, 2001. 123(2): p. 229-233.
77. S.K. Yeh, Y.C. Liu, W.Z. Wu, K.C. Chang, W.J. Guo, S.F. Wang, Thermoplastic polyurethane/clay nanocomposite foam made by batch foaming. Journal of Cellular Plastics, 2013. 49(2): p. 119-130.
78. L. Urbanczyk, C. Calberg, C. Detrembleur, C. Jérôme, M. Alexandre, Batch foaming of SAN/clay nanocomposites with scCO2: A very tunable way of controlling the cellular morphology. Polymer, 2010. 51(15): p. 3520-3531.
79. X. Gao, Y. Chen, Z. Xu, L. Zhao, D. Hu, Supercritical CO2 foaming of thermoplastic polyurethane composite: simultaneous simulation of cell nucleation and growth coupling in Situ visualization. Industrial and Engineering Chemistry Research, 2022. 61(36): p. 13474-13487.
80. A.Wong, Y.T. Guo, and C.B. Park, Fundamental mechanisms of cell nucleation in polypropylene foaming with supercritical carbon dioxide-Effects of extensional stresses and crystals. Journal of Supercritical Fluids, 2013. 79: p. 142-151.
81. R.Rangappa, and S.-K. Yeh, Effect of N2 plasticization on the crystallization of different hardnesses of thermoplastic polyurethanes. The Journal of Supercritical Fluids, 2022. 189: p. 105726.
82. X. Gao, W. Qiang, L. Zhao, Z. Xu, L. Tao, M. Tian, Z. Liu, D. Hu, Effect of alcohols-regulated crystallization on foaming process and cell morphology of polypropylene. The Journal of Supercritical Fluids, 2021. 175: p. 105271.
83. 李佳芸, 以添加不同表面處理的奈米矽顆粒對於熱塑性聚氨酯的發泡影響,碩士論文,國立臺灣科技大學,材料科學與工程研究所.2022.