مروری بر جنبه های ترمودینامیکی اسفنج های گرمانرم

نوع مقاله: مروری

نویسندگان

گروه مهندسی پلیمر، دانشکده مهندسی شیمی، دانشگاه تربیت مدرس، تهران، ایران

چکیده

در دو روش رایج برای تولید اسفنج‌های بسپاری، از عامل‌های اسفنج‌ساز شیمیایی و فیزیکی استفاده می‌شود. عامل اسفنج‌ساز فیزیکی در فشار و دمای بالاتر از شرایط بحرانی آن، تا حدی در بسپار حل شده و در اثر ایجاد افت فشار سریع یا افزایش دما در مخلوط، طی سه مرحله هسته‌گذاری، رشد و به ­هم‌ پیوستگی، ساختار اسفنج شکل می‌گیرد. در مرحله هسته‌گذاری، در اثر ایجاد فراسیر ‌شدگی، ناپایداری ترمودینامیکی در مخلوط‌ ایجاد شده که موجب تمایل مولکول‌های حلال برای انتقال فازی از حالت فوق‌بحرانی به حالت گاز در جهت کاهش ناپایداری می‌شود. با غلبه بر سدی از انرژی، انرژی آزاد سامانه کاهش یافته و هسته ­های پایداری از مولکول‌های گاز در حجم‌های آزاد بین زنجیرهای بسپارشکل می‌گیرند. با نفوذ مولکول‌های گاز به درون هسته‌ها، رشد و به ­هم پیوستگی آن­ ها رخ می ­دهد که سرانجام رشد متوقف شده و ساختار اسفنج تثبیت می‌شود. با افزایش بازده مرحله هسته‌گذاری، تعداد هسته‌های پایدار بیش ­تری ایجاد شده و میزان رشد و به­ هم‌ پیوستگی آنها نیز کاهش می‌یابد. بنابراین پیش‌بینی میزان سته‌گذاری عاملی مهم در کنترل ساختار اسفنج‌های گرمانرم بوده و بررسی مرحله هسته‌گذاری به کمک نظریه‌های هسته‌گذاری انجام‌پذیر است. نظریه کلاسیک هسته‌گذاری روش اصلی و اولیه بررسی پدیده هسته‌گذاری در اسفنج‌های گرمانرم بوده که به دلیل ناهمخوانی مناسب نتیجه­ های آن با نتیجه­ های آزمایشگاهی، اصلاحاتی بر روی آن آنجام شده است. همچنین نظریه‌های رقیب دیگری همچون نظریه‌های عاملیت چگالی و میدان خودسازگار نیز
به ­وجود آمده‌اند. هدف اصلی این مقاله مروری، بررسی جامع نظریه کلاسیک هسته‌گذاری  و اصلاحات آن و بررسی اجمالی دیگر نظریه‌ها در اسفنج‌های گرمانرم است.

کلیدواژه‌ها

موضوعات


[1] Colton J.S., Suh N.P., The Nucleation of Microcellular Thermoplastic Foam with Additives. Part I. Theoretical Considerations, Polym. Eng. Sci., 27:485-492 (1987).

[2] Kima Y., Park C.B., Chen P., Thompson R.B., Towards Maximal Cell Density Predictions for Polymeric Foams, Polym., 52:5622-5629 (2011).

[3] Janani H., Famili M.H.N., Investigation of a Strategy for Well Controlled Inducement of Microcellular and Nanocellular Morphologies in Polymers, Polym. Eng. Sci., 10:1558-1570 (2010).

[4] Maghsoud Z., Famili M.H.N., Madaeni S.S., Phase Diagram Calculations of Water/Tetrahydrofuran/Poly(vinyl chloride) Ternary System Based on a Compressible Regular Solution Model, I.P.J., 19:581-588 (2010).

[5] Enayati M.S., Famili M.H.N., Janani H., Production of Polystyrene Open-Celled Microcellular Foam in Batch Process by Supercritical CO2, Iran. J. Polym. Sci. Tech. (Persian), 23:223-234 (2010).

[6] Enayati M.S., Famili M.H.N., Janani H., Open-Celled Microcellular Foaming and the Formation of Cellular Structure by a Theoretical Pattern in Polystyrene, I.P.J, 22:417-428 (2013).

[7] Gutierrez C., Rodriguez J.F., Gracia I., Development of a Strategy for the Foaming of Polystyrene Dissolutions in scCO2, J. Supercrit. Fluids, 76:126-134 (2013).

[8] Liu T., Li D., Zhao L., Manipulation of Polymer Foam Structure Based on CO2-Induced Changes in Polymer Fundamental Properties, Particuology, 8:607-612 (2010).

[9] Baoa M.B., Liua T., Zhao L., A Two-Step Depressurization Batch Process for the Formation of Bi-Modal Cell Structure Polystyrene Foams Using scCO2, J. Supercrit. Fluids, 55:1104–1114 (2011).

[10] Tomasko D.L., Burley A., Development of CO2 for Polymer Foam Applications, J. Supercrit. Fluids, 47:493–499 (2009).

[11] Kashchiev D., "Nucleation: Basic Theory with Applications", Butterworth-Heinemann, UK (2000).

[12] Vehkamaki H., “Classical Nucleation Theory in Multicomponent Systems", Springer, Finland (2006).

[13] Merikanto J., Lauri A., Vehkama H., Origin of the Failure of Classical Nucleation Theory: Incorrect Description of the Smallest Clusters, Phys. Rev. Lett., 98:145702-145706 (2007).

[14] Goel S.K., Beckman E.J., Generation of Microcellular Polymeric Foams Using Supercritical Carbon Dioxide. I: Effect of Pressure and Temperature on Nucleation, Polym. Eng. and Sci., 34:1137-1147 (1994).

[15] Han J.H., Han C.D., Bubble Nucleation in Polymeric Liquids. II. Theoretical ConsiderationsJ. Polym. Sci., Part B: Polym. Phys., 28: 743-761 (1990).

[16] Kima Y., Park Ch.B., Chen P., Thompson R.B., Maximal Cell Density Predictions for Compressible Polymer Foams, Polym., 54: 841-845 (2013).

[17] Talreja M., "Towards Understanding Interfacial Phenomena in Polymer-CO2 Systems", PhD Thesis, USA, The Ohio State University (2010).

[18] Talreja M., Kusaka I., Tomasko D.L., Density Functional Approach for Modeling CO2 Pressurized Polymer Thin Films in Equilibrium, J. Phys. Chem., 130: 084902-084907 (2009).

[19] Ghosh S. and Ghosh S.K., Density Functional Theory of Size-Dependent Surface Tension of Lenard-Jones Fluid Droplets Using a Double Well Type Helmholtz Free Energy Functional, J. Phys. Chem., 135: 124710-124718 (2011).

[20] Ghosh S., Ghosh S.K., Homogeneous Nucleation in Vapor-Liquid Phase Transition of Lennard-Jones Fluids: A Density Functional Theory Approach, J. Phys. Chem., 134: 024502-024510 (2011).

[21] Parra I.E., Graa J.C., Influence of the Attractive Pair-Potential in Density Functional Models of Nucleation, The J. Phys. Chem., 132:034702-034711 (2010).

[22] Kima Y., Park C.B., Chen P., Thompson R.B., Origins of the Failure of Classical Nucleation Theory for Nanocellular Polymer Foams, Soft. Matter., 7:7351-7358 (2011).

[23] Kiran E., Foaming Strategies for Bioabsorbable Polymers in Supercritical FLuid Mixtures. Part II. Foaming of poly(ε-caprolactone-co-lactide) in Carbon Dioxide and Carbon Dioxide + Acetone Fluid Mixtures and Formation of Tubular Foams Via Solution Extrusion, J. Supercrit. Fluids, 54: 308-319 (2010).

[24] Han J.H., Han C.D., Bubble Nucleation in Polymeric Liquids. I. Bubble Nucleation in Concentrated Polymer Solutions, J. Polym. Sci. Part B: Polym. Phys.  28: 711-741 (1990).

[25] Han J.H., Han C.D., Bubble Nucleation in Polymeric Liquids. II. Theoretical Considerations, J. Polym. Sci. Part B: Polym. Phys., 28: 743-761 (1990).

[26] Ott B.A., Caneba G., Solubility of Supercritical CO2 in Polystyrene during Foam Formation via Statistical Associated Fluid Theory (SAFT) Equation of State, Journal of Minerals & Materials Characterization & Engineering, 9:411-426, (2010).

[27] Kasturirangan A., Teja A.S., Correlation of Cloud Points in CO2 Fluorinated Polymer Systems, J. Chem. Eng. Data., 55: 4385-4389 (2010).

[28] Yuan Y., Teja A.S., Extension of a Compressible Lattice Model to CO2 + Cosolvent + Polymer Systems, J. Supercrit. Fluids, 55:358-362 (2010).

[29] Kasturirangan A., Koh C.A., Teja A.S., Glass-Transition Temperatures in CO2 Polymer Systems: Modeling and Experiment, Ind. Eng. Chem. Res., 50:158-162 (2011).

[30] Xiong Y. and Kiran E., Kinetics of pressure-Induced Phase Separation (PIPS) in Polystyrene + Methylcyclohexane Solutions at High Pressure, Polym., 41:3759-3777 (2000).

[31] Mortezaie M., Famili M.H.N., Kokabi M., Influence of the Particle size on the Viscoelastic Glass Transition of Silica-Filled Polystyrene, J. Appl. Polym. Sci., 115: 969-975 (2010).

[32] Zakian S.E, Famili M.H.N., Ako M., Hetrogeneous Nucleation in Batch Foaming of Polystyrene in Presence of Nanosilica as a Nucleating Agent, Iran. J. Polym. Sci. Tech. (persian), 25:231-240 (2012).

[33] Famili M.H.N., Janani H., Enayati M.S., Foaming of a Polymer–Nanoparticle System: Effect of the Particle Properties, J. Appl. Polym. Sci., 119:2847-2856 (2011).

[34] Mortezaie M., Famili M.H.N., Kalaee M.R., Effect of Immobilized Interfacial Layer on the Maximum Filler Loading of Polystyrene/Silica Anocomposites, J. Reinfo. Plas. and Compo., 30:593-599 (2011).

[35] Hwang S.S., Peming P.H., Effects of Silica Particle Size on the Structure and Properties of Polypropylene/Silica Composites Foams, J. Ind. Eng. Chem., 19:  1377–1383 (2013).

[36] Zenga ch., Hossieny N., Wang B., Morphology and Tensile Properties of PMMA Carbon Nanotubes Nanocomposites and Nanocomposites Foams, Compos. Sci. Technol.,  82:29–37 (2013).

[37] Costeux S., Zhu L., Low Density Thermoplastic Nanofoams Nucleated by Nanoparticles, Polym., 54:2785-2795 (2013).

[38] Soares F.A., Nachtigall S.M, Effect of Chemical and Physical Foaming Additives on the Properties of PP/Wood Flour Composites, Polym. Test., 32:640-646 (2013).

[39] Nofar M.R., Tabatabaei A.R., Park C.B., Effects of Nano-/Micro-Sized Additives on the Crystallization Behaviors of PLA and PLA/CO2 Mixtures, Polymer, 54:2382-2391 (2013).

[40] Goren K., Chen L., Ozisik R., Influence of Nanoparticle Surface Chemistry and Size on Supercritical Carbon Dioxide Rocessed Nanocomposite Foam Morphology, J. Supercrit. Fluids, 51:420-427 (2010).

[41] Salernoa A., Maioc E., Iannaceb S., Netti P.A., Solid-State Supercritical CO2 Foaming of PCL and PCL-HA Nano-Composite: Effect of Composition, Thermal History and Foaming Process on Foam Pore Structure, J. Supercrit. Fluids, 58:158-167 (2011).

[42] Thanh V.,  Duchet J., Gerard J., Processing of Nanocomposite Foams in Supercritical Carbon Dioxide. Part I: Effect of Surfactant, Polym., 51:3436–3444 (2010).

[43] Gang Z.C., Irreversible Thermodynamics of Nucleation, J. Coll. Int. Sci., 124: 262-268(1988).

[44] Zenga ch., Hossieny N., Wang B., Synthesis and Processing of PMMA Carbon Nanotube Nanocomposite Foams, Polym., 51:655–664 (2010).

[45] Chen L., Ozisik R., Schadler L.S., The Influence of Carbon Nanotube Aspect Ratio on the Foam Morphology of MWNT/PMMA Nanocomposite Foams, Polymer, 51:2368-2375 (2010).

[46] Kim S.G., Siu N.L., Chul B.P., Sain M., The Effect of Dispersed Elastomer Particle Size on Heterogeneous Nucleation of TPO with N2 Foaming, Chem. Eng. Sci., 66:3675-3686 (2011).

[47] Riahinezhad M., Ghasemi I., Karrabi M., Azizi H., An Investigation on the Correlation between Rheology and Morphology of Nanocomposite Foams Based on Low-Density Polyethylene and Ethylene Vinyl Acetate Blends, Polym. Composite., 31:1808–1816 (2010).

[48] Ghasemi I., Farsheh A.T., Masoomi Z., Effects of Multi-Walled Carbon Nanotube Functionalization on the Morphological and Mechanical Properties of Nanocomposite Foams Based on Poly(vinyl chloride)/(wood flour)/ (multi-walled carbon nanotubes), J. Vinyl. Addit. Techn., 18:161-167 (2012).

[49] Zakian S.E, Famili M.H.N., Ako M., Controlling Foam Morphology of Polystyrene via Surface Chemistry, Size and Concentration of Nanosilica Particles, J. Mate. Sci., 49:6225-6239 (2014).

[50] Liao X., Yaogai G.L., C.B. Park, Chen P., Interfacial Tension of Linear and Branched PP in Supercritical Carbon Dioxide, J. Supercrit. Fluids, 55:386–394 (2010).

[51] Tsivintzelis I., Angelopoulou A.G., Panayiotou C., Foaming of Polymers with Supercritical CO2: An experimental and Theoretical Study, Polymer, 48:5928-5939 (2007).

[52] Panayiotou C., Pantoula M., Stefanis E., Tsivintzelis I., Nonrandom Hydrogen-Bonding Model of Fluids and Their Mixtures. 1. Pure Fluids, Ind. Eng. Chem. Res., 43:6592-6606 (2004).

[53] Panayiotou C., Tsivintzelis I., Economou I.G., Nonrandom Hydrogen-Bonding Model of Fluids and Their Mixtures. 2. Multicomponent Mixtures, Ind. Eng. Chem. Res., 46:2628-2636 (2007).

[54] Oxtoby D.W., Density functional Methods in the Statistical Mechanics of Materials, Annu. Rev. Mater. Res., 32:39-52 (2002).

[55] Schmelzer J.W.P., Comments on the Nucleation Theorem, J. Colloid Interface Sci. 242:354–372 (2001).

[56] Oxtoby D.W., Density Functional Methods in the Statistical Mechanics of Materials, Annu. Rev. Mater. Res., 32:39-52 (2002).