Polistirenin Süspansiyon Polimerizasyonuyla Üretiminde Tanecik Boyutu Dağılımının Reaktör Geometrisi ve Karıştırma Koşulları ile İlişkisi

Year 2018, Volume: 33 Issue: 2, 125 - 138, 30.06.2018

Ebru Erünal

https://doi.org/10.21605/cukurovaummfd.508945

Cited By: 1

Abstract

İlgili çalışmada, süspansiyon polimerizasyonu yoluyla elde edilen polistirenin reaktör geometrisi ve karıştırma koşullarına bağlı olarak parçacık büyüklüğü ve ortalama moleküler ağırlık dağılımları incelenmiştir. Karıştırma işlemi, ikili marin tipi pervaneli bir karıştırıcı ile 1600 dev/dak ve 2000 dev/dak olmak üzere iki farklı karıştırma hızında gerçekleştirilmiştir. Etkin karıştırma alanını kaybetmemek için her iki reaktörün de çaplarının birbiriyle uyumlu olmasına dikkat edilmiş, ayrıca polimerizasyonun tümüyle bittiğinden emin olmak için tüm deneyler yaklaşık 8 saat sonunda kesilmiştir. Silindirik reaktörde beklenildiği üzere artan karıştırıcı hızıyla küçük çaplı taneciklerin arttığı ve dağılımın bu aralıkta yoğunlaştığı gözlenirken, küresel reaktörde ise yüksek karıştırıcı hızının vorteks oluşumuna ve tanecik boyutlarının kontrolsüze gelişmesine neden olduğu ancak düşük hızlarda ise çok daha etkin bir yoğunlukta küçük tanecik aralığının elde edildiği görülmüştür. Öte yandan, ortalama moleküler ağırlığı dağılımı tayinleri küresel reaktörde elde edilen polistirenin silindirik reaktörde elde edilenlere göre daha düşük moleküler ağırlık dağılımına sahip olduklarını ortaya koymuştur. Bunun nedeninin küresel reaktörde, karıştırıcı pervanelerinin reaktör duvarlarına göre yukarıdan aşağıya sabit mesafede olmayışı ve dolayısıyla silindirik reaktöre nazaran etkin bir kütle ve ısı transferinin sağlanamayarak polimer zincirlerinin kısalmasına ve polidispertiste endeksinin yükselmesine yol açtığı düşünülmektedir.

Keywords

Süspansiyon polimerizasyonu, Polistiren, Karıştırma, Parçacık boyut dağılımı

Bead Size Distribution Dependency on Reactor Geometry and Agitation Conditions of Polystyrene Production with Suspension Polymerization

Abstract

The relation between the reactor geometry and agitation conditions on particle size distribution for suspension polymerization of polystyrene was analyzed. The reactor geometries were selected as cylindrical and spherical, respectively. Mechanical agitation was provided via double-impeller Marine type propeller at 1600 rpm and 2000 rpm. The diameters of the reactors were selected approximately the same for cylindrical and spherical reactors in order to keep effective mixing area similar in both geometries. All experiments were conducted around 8 hours to complete the polymerization reaction. Particle size distribution analyses showed that at faster agitation conditions in cylindrical reactor narrower and smaller particles are obtained as expected. On the other hand, in spherical reactor, vortex formation and non-uniform particle size distribution were observed at faster agitation. Interestingly, when agitation speed was decreased in spherical reactor, quite narrower and smaller particle size distributions with respect to cylindrical reactor were obtained. However, the number and average molecular weight analyses suggested that the particles obtained from spherical reactor has a lower molecular weight distribution than particles from cylindrical reactor. This was attributed to the decrease in effective mixing area due to the non-homogenous changes of the distance between reactor walls and impellers throughout the spherical reactor. The geometry change to spherical geometry obviously causes diminishing in mass transfer of initiators and suspension stabilizers so that a shortening of polymer chains lead to a slight increase in polydispersity index. 

Keywords

Suspension polymerization, Polystyrene, Mixing, Particle size distribution

References

• 1. Sterbacek, Z., Tausk, P., 1965. Mixing in the Chemical Industry, Pergamon, London, 55-60.
• 2. Baldyga, J., Bourne, J.R., 1999. Turbulent Mixing and Chemical Reactions, Wiley, 73-80, New York.
• 3. Paul, E.L., Atiemo-Obeng, V.A., Kresta, S.M., 2004. Handbook of Industial Mixing, WileyInterscience, New York, 116-130.
• 4. North American Mixing Forum. Mixing of Bulk Chemicals. http://mixing.net. [Online] March 14, 2011. [Cited: March 25, 2017.] http://mixing.net/Featured/Mixing-in-BulkChemical-Industry.pdf
• 5. Bourne, J., 2003. Mixing and the Selectivity of Chemical Reactions. Organic Process Research & Development, 7, 471−508.
• 6. Matar, S., Hatch, L.F., 2001. Chemistry of Petrochemical Processes (Second Edition), Butterworth-Heinemann, Woburn, 301-322.
• 7. Scheirs, J., Priddy, D.B., 2003. Modern Styrenics Polymers. John Wiley & Sons Ltd., England.
• 8. Seymor, R., Corraher, C. E., 2003. Polymer Chemistry (Sixth Edition), Dekker, New York, 344-357.
• 9. Kotoulas, C., Kiparissides, C., 2006. A Generalized Population Balance Model for the Prediction of Particle Size Distribution in Suspension Polymerization Reactors. Chemical Engineering Science, 61, 332-346.
• 10. Dowding, P.J., Vincent, B., 2000. Suspension Polymerisation to form Polymer Beads. 2000, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 161, 259-269.
• 11. Erbay, E., Bilgic, T., Karali, M., Savasci, O., 1992. Polystyrene Suspension Polymerization: The Effect of Polymerization Parameters on Particle Size and Distribution. Polymer-Plastics Technology and Engineering, 31(7-8),589-605.
• 12. Vivaldo-Lima, E., Wood, P., Hamielec, A., Penlidis, A., 1997. An Updated Review on Suspension Polymerization. Industrial Engineering Chemistry Research, 36, 939-965.
• 13. Hukkanen, E., Braatz, R., 2005. Influence of Semi-Batch Operations on Morphological Properties of Polystyrene Made in Suspension Polymerization. American Control Conference Proceedings, Portland, 925-930.
• 14. Nogueira, A.L., Quadri, B.M., Araujoa, P.H., Machado, R.A., 2012. Influence of Semi-Batch Operations on Morphological Properties of Polystyrene Made in Suspension Polymerization. Procedia Engineering, 42, 1045-1052.
• 15. Lenzi, M., Silva, F., Lima, E., Pinto, J., 2003. Semibatch Styrene Suspension Polymerization. Journal of Applied Polymer Sciences, 89, 3021-3038.
• 16. Tanaka, M., Izumi, T., 1985. Application of Stirred Tank Reactor Equipped with Draft Tube to Suspension Polymerization of Styrene. Journal of Chemical Engineering of Japan, 4(18), 354-358.
• 17. Mitchell, G. 1986. Effect of Agitator Geometry and Speed on Suspension Polystyrene. M. Eng. Thesis. Ontairo: McMaster University.
• 18. Hosogai, K., Tanaka, M., 1992. Effect of Impeller Diameter on Mean Droplet Diameter in Circular Loop Reactor. The Canadian Journal of Chemical Engineering, 70, 645-653.
• 19. Jahanzad, F., Sajjadi, S., Brooks, B.W., 2005. Characteristic Intervals in Suspension Polymerisation Reactors: An Experimental and Modelling Study. Chemical Engineering Science, 60, 5574-5589.
• 20. Jahanzad, F., Sajjadi, S., Yianneskis, M., Brooks, B., 2008. In Situ Mass-suspension Polymerisation. Chemical Engineering Science, 63, 4412- 4417.
• 21. Patel, H., 2007. Computational Fluid Dynamics (CFD) Analysis of Mixing in Styrene Polymerization. M.Sc. Thesis, Toronto: Ryerson University.
• 22. Hui, A. W. T., 1967. Free Radical Polymerization of Styrene in a Batch Reactor up to High Conversion. M.Eng.Thesis, Ontaria: McMaster University.
• 23. Cole, W.M., 1975. Experimental Study of Mixing Patterns in Continuous Polymerization Reactors and their Effect on Polymer Structure. AICHE Symposium Series, 160, 51-60.
• 24. Harada, M., Tanaka, K., Eguchi, W., Nagata, S., 1968. The Effect of Micro-Mixing on the Homogeneous Polymerization of Styrene in a Continuous Flow Reactor. Journal of Chemical Engineering of Japan, 2, 148-152.
• 25. Hukkanen, E.J., Braatz, R.D., 2005. Identification of Particle-Particle Interactions in Suspension Polymerization Reactors. Portland: American Control Conference, 925-930.
• 26. Erdoğan, S., Alpbaz, M., Karagöz, A.R., 2002. The Effect of Operational Conditions on the Performance of the Batch Polymerization Reactor. Chemical Engineering Journal, 86, 259-268.
• 27. Kemmere, M.F., Meuldljk, J, Drinkenburg, A.A.H., German, A.L., 2001. Emulsification in Batch-Emulsion Polymerization of Styrene and Vinyl Acetate: A Reaction Calorimetric Study, Journal of Applied Polymer Sciences, 79(5), 944-957.
• 28. Saliakas, V., Kotoulas, C., Meimaroglou, D., Kiparissides, C., 2008. Dynamic Evolution of the Particle Size Distribution in Suspension Polymerization Reactors: A Comparative Study on Monte Carlo and Sectional Grid Methods. The Canadian Journal of Chemical Engineering, 86, 924-936.
• 29. Platzer, B., Klodt, R.D., Hamann, B., Henkel, K.D., 2005. The Influence of Local Flow Conditions on the Particle Size Distribution in an Agitated Vessel in the Case of Suspension Polymerisation of Styrene. Chemical Engineering and Processing, 44, 1228-1236.
• 30. Qiao, S., Wang, R., Yan, Y., Yang, X., 2014. Computational Fluid Dynamics Analysis to Effects of Geometrical Design and Physical Property on Complete Suspension of Floating Solids in Stirred Tanks. Asia-Pacific Journal of Chemical Engineering, 9, 866-876.
• 31. Widjaja, R., Widjaja, E. 2011. Suspension Polymerization of Styrene Using Zinc Oxide as a Suspension. Agent Journal of Materials Science and Engineering (B1), 404-409
• 32. Machado, R.A.F., Bolzan, A., 1998. Control of Batch Suspension Polymerization Reactor. Chemical Engineering Journal, 70, 1-8. 33. Arshady, R., 1992. Suspension, Emulsion, and Dispersion Polymerization: A Methodological Survey, Colloidal Polymer Science, 270, 717-732.
• 34. Ahmed, S.M., 1984. Effects of Agitation, and The Nature of Protective Colloid on Particle Size During Suspension Polymerization. Journal of Dispersion Science and Technology, 5, 421.
• 35. Kotoulas, C., Bousquet, J., Kiparissides, C. 2004. Advanced Software Tools, Dynamic Simulation of Particle Size Distribution in Industrial Suspension Polymerization Reactors, Workshop of CPERI.
• 36. Choi, J., Kwak,, S.Y., Kang, S., Lee, S.S., Park, M., Lim, S., Kim, J., Choe, C.R., Hong, S.I. 2002. Synthesis of Highly Crosslinked Monodisperse Polymer Particles: Effect of Reaction Parameters on the Size and Size Distribution. Journal of Polymer Science Part A: Polymer Chemistry, 40, 23.
• 37. Polacco, G., Basile, G., Palia, M., Semino. D. 2000. A Simple Technique for Measuring Particle Size Distributions During Suspension Polymerization, Polymer Journal, 32(8), 688-693.
• 38. Paine, A.J., Luymes, W., McNulty, J. 1990. Dispersion Polymerization of Styrene in Polar Solvents. 6. Influence of Reaction Parameters on Particle Size and Molecular Weight in Poly (N-vinylpyrro1idone)-Stabilized Reactions. Macromolecules, 23, 3104-3109.
• 39. Yang, B., Takahashi, K., Takeishi. M., 2000. Styrene Drop Size and Size Distribution in an Aqueous Solution of Poly (vinyl alcohol) Industrial Engineering Chemistry Research, 39, 2085-2090.
• 40. Maggioris, D., Goulas, A., Alexopoulos, A.H., Chatzi, E.G., Kiparissides, C., 2000. Prediction of Particle Size Distribution in Suspension Polymerization Reactors: Effect of Turbulence Nonhomogeneity. Chemical Engineering Science, 55, 4611-4627.
• 41. Kaflas, G., Yuan, H., Ray, W.H., 1993. Modelling and Experimental Studies of Aqueous Suspension Polymerization Processes. 2. Experiments in Batch Reactors. Industrial Engineering Chemistry Research, 32, 1831-1838.
• 42. Nienow, A.W., Harnby, N., Edwards, M.F., 1997. Mixing in the Process Industries. Second Edition. Oxford: Butterworth-Heinemann.
• 43. Erdmenger, T., Becer, C.R., Hoogenboom, R., Schubert, U.S., 2009. Simplfiying the FreeRadical Polymerization of Styrene: Microwave-Asisted High-Temperture Auto Polymerizations. Australian Journal of Chemistry, 62, 58-63.
• 44. Tosun, G., 1992. A Mathematical Model of Mixing and Polymerization in a Semibatch Stirred Tank Reactor, AIChE, 38(3), 425-437.