38 research outputs found
Synthesis And Characterization Of Polystyrene/layered Hydroxide Salt Nanocomposites [síntese E Caracterização De Nanocompósitos De Poliestireno/hidroxissal Lamelar]
No full textPolystyrene/layered hydroxide salt (LHS) modified with sodium dodecyl sulfate was synthesized by in situ polymerization. The materials synthesized were characterized by gravimetry, X-ray diffraction (XRD), thermogravimetry analyses (TGA), differential scanning calorimetry (DSC) and the flammability test (FT). XRD demonstrated that synthesized nanocomposites in all compositions studied showed poor global dispersion of LHS in polystyrene. TGA showed a slight decrease in thermal stability. DSC curves showed that the glass transition temperature of polystyrene and nanocomposites were similar. The FT showed that the nanocomposite with low load of LHS exhibited good results.3711821Botan, R., Nogueira, T.R., Lona, L.M.F., Wypych, F., (2011) Polímeros, 21, p. 34Souza, M.A., Pessan, L.A., Rodolfo, Jr.A., (2006) Polímeros, 16, p. 257Nogueira, T., Botan, R., Wypych, F., Lona, L., (2011) Composites Part A, 42, p. 1025Camargo, P.H.C., Satyanarayana, K.G., Wypych, F., (2009) Mater. Res., 12, p. 1Arizaga, G.G.C., Satyanarayana, K.G., Wypych, F., (2007) Solid State Ionics, 178, p. 1143Alexandre, M., Dubois, P., (2000) Mater. Sci. Eng., 28, p. 1Pavlidou, S., Papaspyrides, C.D., (2008) Prog. Polym. Sci., 33, p. 1119Yano, K., Usuki, A., Okada, A., Kurauchi, T., Kamigaito, O., (1993) J. Polym. Sci., Part A: Polym. Chem., 31, p. 2493Esteves, A.C.C., Barros-Timmons, A., Trindade, T., (2004) Quim. Nova, 27, p. 798Nogueira, T., Botan, R., Wypych, F., Lona, L., (2012) J. Appl. Polym. Sci., 124, p. 1764Vaia, R.A., Teukolsky, R.K., Giannelis, E.P., (1994) Chem. Mater., 6, p. 1017Avalos, F., Ortiz, J.C., Zitzumbo, R., López-Manchado, M.A., Verdejo, R., Arroyo, M., (2008) Eur. Polym. J., 44, p. 3108Leite, I.F., Malta, O.L., Raposo, C.M.O., Canedo, L.E., Carvalho, L.H., Silva, S.M.L., (2011) Polímeros, 21, p. 195Marangoni, R., Ramos, L.P., Wypych, F., (2009) J. Colloid Interface Sci., 330, p. 303Botan, R., Nogueira, T.R., Wypych, F., Lona, L.M.F., (2012) Polym. Eng. Sci., 52, p. 1754Kotal, M., Kuila, T., Srivastava, S.K., Bhowmick, A.K., (2009) J. Appl. Polym. Sci., 114, p. 2691Qiu, L., Chen, W., Qu, B., (2005) Colloid Polym. Sci., 283, p. 1241Qiu, L., Chen, W., Qu, B., (2005) Polym. Degrad. Stab., 87, p. 433http://www.boedeker.com/bpi-ul94.htm, acessada em Setembro 2013Nogueira, T., Botan, R., Neto, J.C.M., Wypych, F., Lona, L., (2013) Adv. Polym. Tech., 32, pp. E66
Cyclic Trifunctional Peroxide On Living Free Radical Polymerization
No full textUntil the mid 90's, free radical polymerization (FRP) was characterized by producing polymers with high average molecular weig hts (1×10 5-1×106) since the beginning of polymerization, index of polidispersity (PDI) greater than 1.5 and wide molecular weight distribution (MWD). When necessary to produce polymers with more defined structure, it was usually used anionic polymerization, which is capable to produce polymers with narrow molecular weight distribution and PDI around 1.0 (1.1-1.2). The ionic polymerization, however, needs to be held in a high degree of purity and in the absence of inhibitors, what make the ionic polymerization expensive and not very practical from the industrial point of view. A promising alternative to ionic polymerization has been the living radical polymerization (LFRP), which is much more robust to the impurities and kind of solvent and it is able to produce polymers with polidispersity close to one. Nevertheless, the LFRP presents lower polymerization rates compared to standard and smaller polymer chains (lower molecular weights averages). In this work the effect of cyclic trifunctional initiator on the Living Free Radical Polymerization is analyzed. The Nitroxide Mediated Radical Polymerization (NMRP) is considered, using TEMPO as controller and styrene as monomer. It can be observed that the polidispersity can vary in a very broad range when this initiator is used, changing from PDI lower than 1.5 until PDI bigger than 4.0, depending on the operating conditions considered. Copyright © 2009, AIDIC Servizi S.r.l.17169174Cerna, J.R., Morales, G., Eyler, G.N., Canizo, A.I., Bulk Polymerization of Styrene Catalyzed by Bi- and Trifunctional Cyclic Initiators (2002) J. Applied Polymer Sci, 83, pp. 1-11Dias, R.S., Gonçalvez, M.C., Lona, L.M.F., Vivaldo-Lima, E., McManus, N.T., Penlidis, A., Nitroxide - Mediated Radical Polymerization of Styrene Using Mono and Di - Functional Initiators (2006) Chemical Engineering Science, , 16 Decembe
Baffled Tubular Reactor For Emulsion Polymerisation Of Styrene For High Performance Operation
No full textEmulsion Homopolymerization of styrene into tubular reactor with angle internal baffles as static mixer is presented in this work. It is assumed cylindrical one-dimensional model, fully developed laminar plug flow, and the model solved by finite volume method. Also it is considered the Smith-Ewart model to estimate the monomer conversion and Arrhenius chemical kinetics as laminar finite-rate model to compute chemical source. The objective is to model and simulate the behavior of baffles with reactor diameter effect in constant reaction temperature. The results have the performance of baffled reactor with desired properties of polystyrene.GILBERT, R.G., (1995) Emulsion Polymerization, A Mechanistic Approach, , Academic PressLondon;SCHOLTENS, C.A., (2002) CIP-DATA Library Technische Universiteit Eindhoven, Ter Verkrijging van de graad van DoctorBOCKHORN, H., Mathematical Modeling (1992) ULLMANN'S Encyclopedia of Industrial Chemistry, B1, p. 2GAO, J., PENLIDIS, A., Mat. Mod. and Comp. Simulator/database for Em. Polymerizations (2002) Prog. Polym. Sci, 27, pp. 403-535MACIEL FILHO, R., and DOMINGUES, A., ISCRE 12 (Inter. Symposium on Chemical Reaction Engineering), Turin, Itália, 1992MENDOZA MARIN, F.L.Modelagem, Simulação e Analise de Desempenho de Reatores Tubulares de Polimerização com Deflectores Angulares InternosTese de Doutorado, FEQ/UNICAMP, Campinas, 2004BATAILE, P., VAN, B.T., PHAM, Q.B., (1982) Journal of Polymer Science: Polymer Chemistry Edition, 20, pp. 795-810MENDOZA MARÍN, F.L., LONA, L.M.F., WOLF MACIEL, M.R., MACIEL FILHO, R., New Emulsion Polymerization Tubular Reactor with Internal Angular Baffles: Reaction Temperature Effect. Journal (2006) Journal of Applied Polymer Science, 100, pp. 2572-2581. , IssueMENDOZA MARÍN, F.L., LONA, L.M.F., WOLF MACIEL, M.R., MACIEL FILHO, R., Numerical Method of Finite Volume Method for New Emulsion Polymerization Tubular Reactor with Internal Angle Baffles. International Journal of Chemical Reaction Engineering (2006), submittedPATANKAR, S.V., (1980) Numerical Heat Transfer and Fluid Flow, , Hemisphere Publishing CorporationNew YorkVERSTEEG, H.K., MALALASEKERA, W., (1998) The Finite Volume Method, , 2nd Ed, Addison Wesley Longman Limited
Computational And Experimental Investigation Of Free Radical Polymerization Of Styrene Using A Multifunctional Initiator
No full textLately, the study of peroxides multifunctional initiators has been explored in the scientific and industrial field. These initiators are able to increase the reaction rate in a free radical polymerization without decrease the molecular weight of the formed polymer. Besides that they can also generate branches in the polymeric chain, changing the polymer structure. Copyright © 2009, AIDIC Servizi S.r.l.1718011806Machado P.F.M.P.B.Lona, L.M.F.,2005, Development of a Software to Simulate Free Radical Polymerization of Linear and Branched Polymers using Mono-and Bi-Functional Initiators, E. Symp. on Comp. Aided Proc. Eng.-15, 2005, 20 A, 445-450Scorah, M.J., (2005) Modelling of Free Radical Polymerization of Styrene and Methyl Methacrylate by a Tetrafunctional Initiator, , PhD thesis, Dept. of Chem. Eng, University of Waterloo, Waterloo, Ontario, CanadaScorah, M. J.Dhib, R.Penlidis, A., 2007, Recent Advances in the Study of Multifunctional Initiators in Free Radical Polymerizations, Macrom. React. Eng., 1, 209-22
Synthesis And Characterization Of Exfoliated Polystyrene-layered Double Hydroxide Nanocomposites Via In Situ Polymerization [síntese E Caracterização De Nanocompósitos Esfoliados De Poliestireno - Hidróxido Duplo Lamelar Via Polimerização In Situ]
No full textExfoliated nanocomposites of polystyrene (PS) and layered double hydroxide (LDH) compound of zinc, aluminium and sodium dodecyl sulfate, as interlayer anion, have been synthesized via in situ polymerization. The effect from the LDH compositions (0.5, 1, 3, 5% weight) was studied. The nanocomposites were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and Thermogravimetric Analysis (TGA). The XRD and TEM results showed an exfoliated morphology for the nanocomposites in all compositions. With the 50% weight loss taken as a reference, the TGA results indicated significant improvement in thermal stability for all compositions of the nanocomposites, in comparison to pure polystyrene. This is promising for the application of these new materials in many fields of industry and research.2113438Esteves, A.C.C., Timmons, A.B., Trindade, T., (2004) Quím. Nova, 27, p. 795Wang, L., Su, S., Chen, D., Wilkie, C.A., (2009) Polym. Degrad. Stab., 94, p. 770Wing Mai, Y., Zhen Yu, Z., (2006) Polymer Nanocomposites, , CRC press LLC, New YorkOkada, A., Kawasumi, M., Usuki, A., Kojima, Y., Kurauchi, T., Kamigaito, O., (1990) Synthesis and Properties of Nylon-6/clay Hybrids, , Polymer based molecular composites", cap.1, Schaefer D. W. & Mark, J. E. (ed.), PittsburghLiu, Z., Ma, R., Ebina, Y., Iyi, N., Takada, K., Sasaki, T., (2007) Langmuir, 23, p. 861Liu, Z., Ma, R., Osada, M., Iyi, N., Ebina, Y., Takada, K., Sasaki, T., (2006) J. Am. Chem. Soc., 128, p. 4872Leroux, F., Meddar, L., Mailhot, B., Morlat-Thérias, S., Gardette, J.L., (2005) Polymer, (46), p. 3571Sahu, B., Pugazhenthi, G., (2008) J. Polym. Mater., 25, p. 407Wypych, F., Satyanarayana, K.G., (2005) J. Colloid Interface Sci., 285, p. 532Demir, M.M., Memesa, M., Castignolles, P., Wegner, G., (2006) Macromol. Rapid. Comm., 27, p. 763Cavani, F., Trifirò, F., Vaccari, A., (1991) Catal. Today., 11, p. 173Nogueira, T.R., Lona, L.M.F., Mcmanus, N.T., Vivaldo-Lima, E., Penlidis, A., (2010) J. Mater. Sci., 45, p. 1878Del Arco, M., Fernándes, A., Martín, C., Rives, C., (2007) Appl. Clay Sci., 36, p. 133Velu, S., Suzuki, K., Okasaki, M., Osaki, T., Tomura, S., Ohashi, F., (1999) Chem. Mater., 11, p. 2163Qiu, L., Chen, W., Qu, B., (2005) Coll. Polym. Sci., 283, p. 1241Nyambo, C., Songtipya, P., Manias, E., Jimenez-Gascoc, M.M., Wilkie, C.A., (2008) J. Mater. Chem., 18, p. 4827Ding, P., Qu, B., (2005) J. Colloid Interface Sci., 291, p. 13Qiu, L., Chen, W., Qu, B., (2005) Polym. Degrad. Stab., 87, p. 433Manzi-Nshuti, C., Chen, D., Wilkie, C.A., (2009) Polym. Degrad. Stab., 94, p. 129
Numerical Simulation To Evaluate The Effect From Pre-polymerization On The Behavior Of Tubular Reactors [simulação Numérica Aplicada Para Avaliar O Efeito Da Pré-polimerização No Comportamento De Reatores Tubulares]
No full textThe present study uses a phenomenological model to simulate a continuous, two-stage polymerization process. This system is composed by a continuous stirred tank reactor (CSTR) for monomer pre-polymerization (first stage), connected to a tubular reactor (second stage) to carry out the reaction up to high conversion values. A comprehensive non-iso-thermal 2-D model (axial and radial variations) was used to predict the tubular reactor behavior. A polymer characterization model was also developed to provide estimates of the polymer average molecular weight and polydispersity. According to the results, polymerization reactions carried out in a continuous two-stage system provide a polymer with less heterogeneous properties than the one obtained in a single tubular reactor. Besides, it is possible to produce a more homogeneous polymer increasing the viscosity of the mixture fed in the tubular reactor.173250257McGreavy, C., (1994) Polymer Reactor Engineering, , 1st ed, VCH Publishers, New YorkCabral, P. A.Melo, P. A.Biscaia Jr., E. C.Lima, E. L. & Pinto, J. C. - Polym. Eng. Sci., 43, 6, p.1163 (2003);Tien, N.-K.Flaschel, E. & Renken, A. - Polymer Reaction Engineering - Influence of Reaction Engineering on Polymer Properties, Hanser Publishers (1983);Chen, C.C., (1994) Polym. Plast. Technol. Eng, 33 (1), p. 55Lynn, S., Huff, J.E., (1971) AIChe J, 17 (2), p. 475Husain, A., Hamielec, A.E., (1976) AIChe Symp. Series, 72 (160), p. 112Nogueira, A.L., Lona, L.M.F., Machado, R.A.F., (2004) J. Appl. Pol. Sci, 91, p. 871Soroush, M., Kravaris, C., (1993) AIChe J, 39, p. 1920Marten, F.L., Hamielec, A.E., (1982) J. Appl. Pol. Sci, 27, p. 489Stevens, C.J., Mathematical Modeling of Bulk and Solution Free Radical Polymerization in Tubular Reactors (1988), Ph.D. Thesis, University of Winscosin, Madison, EUAHui, A., Hamielec, A.E., (1968) J. Pol. Sci, 25, p. 167Hamer, J.W., Ray, W.H., (1986) Chem. Eng. Sci, 41 (12), p. 3083Holman, J.P., (1963) Heat Transfer, , Mc Graw Hill, New YorkChen, C.C., Nauman, E.B., (1989) Chem. Eng. Sci, 44 (1), p. 179Cutter, L. A. & Drexler, T. D. - Comp. Appl. Pol. Sci., p.13 (1982);Hui, A., Hamielec, A.E., (1972) J. Appl. Pol. Sci, 16, p. 749Husain, A., Hamielec, A.E., (1978) J. Appl. Pol. Sci, 22, p. 1207Kricheldorf, H.R., (1992) Handbook of Polymer Synthesis, , Marcel Dekker, New YorkMcLaughlin, H. S.Mallikarjun, R. & Nauman, E. B. - AIChe J., 32, 3, p.419 (1986);Wyman, C.E., Carter, L.F., (1976) AIChe Symp. Ser, 72 (160), p. 1Powell, F.E., Brooks, B.W., (1995) Chem. Eng. Sci, 50 (5), p. 837Soliman, M. A.Aljarboa, T. & Alahmad, M. - Polym. Eng. Sci., 34, p.1464 (1994);Tossun, G., (1992) AIChe J, 38, p. 42
Artificial Neural Networks Associated To Calorimetry To Preview Polymer Composition Of High Solid Content Emulsion Copolymerizations
No full textArtificial Neural Networks (ANN) have demonstrated to be powerful tools to model non linear systems, such as high solid content latexes produced by emulsion polymerisation. This system has a great importance in the polymeric industry, essentially for environmental reasons, since they usually have water as continuous phase. In order to propose technical and economically feasible alternatives to control polymeric structure, this work is aimed to develop a new methodology based on artificial neural networks associated with calorimetry to preview polymeric structure. The designed artificial neural networks presented excellent results when tested with process condition variations as well as when they were submitted to test concerning to the variation on the proportion of monomers in the latex formulation. Hence, it was possible to conclude that artificial neural networks, associated to calorimetry, lead to an efficient method to preview the polymer composition in emulsion copolymerizations. © 2005 IEEE.422372242Asua, J.M., Urretabizkaia, A., Arzamendi, G., Unzué, M.J., (1994) J. Polym. Sci.: Part A: Polym. Chem., 32, p. 1779El-Aasser, M.S., Leiza, J.R., Sudol, E.D., (1997) J. Appl. Polym. Sci., 64, p. 1797Lovell, P.A., El-Aasser, M.S., (1999) Emulsion Polymerization and Emulsion Polymers, , Ed. John Wiley and Sons, New YorkMcKenna, T.F., Othman, S., Fevotte, G., Santos, A.M., Hamnmouri, H., (1998) DECHEMA Monographien, 134, p. 567. , Wiley-VCH, BerlinZeaiter, J., Gomes, V.G., Romagnoli, J.A., Barton, G.W., Inferential conversion monitoring and control in emulsion polymerisation through calorimetric measurements (2002) Chemical Engineering Journal, 89, p. 37Vieira, R.A.M., Embiruçu, M., Sayer, C., Pinto, J.C., Lima, E.L., Control strategies for complex chemical processes. Applications in polymerization processes (2003) Computers and Chemical Engineering, 27, p. 1307Vicente, M., Leiza, J.R., Asua, J.M., Maximizing production and polymer quality (MWD and composition) in emulsion polymerization reactors with limited capacity of heat removal (2003) Chemical Engineering Science, 58, p. 215Zorzetto, L.F.M., Maciel Filho, R., Wolf-Maciel, M.R., Process modelling development through artificial neural networks and hybrid models (2000) Computers and Chemical Engineering, 24, p. 1355Fernandes, F.A.N., Lona, L.M.F., Development of polymer resins using neural networks (2002) Polímeros: Ciência e Tecnologia, 12 (3), p. 164Zhang, Z., Friedrich, K., Artificial neural networks applied to polymer composites: A review (2003) Composites Science and Technology., 63, p. 1Haykin, S., (1999) Neural Networks - A Comprehensivefoundation -2nd. Ed., , New York: Macmillan College Publishing CompanyRamirez-Beltran, N.D., Jackson, H., Application of neural networks to chemical process control (1999) Computers & Industrial Engineering, 37, p. 387Yu, D.L., Gomm, J.B., Implementation of neural network predictive control to a multivariable chemical reactor (2003) Control Engineering Practice, 11 (11), p. 1315Laugier, S., Richon, D., Use of artificial neural networks for calculating derived thermodynamic quantities from volumetric property data (2003) Fluid Phase Equilibria, 210, p. 247Boillereaux, L.A., Cadet, C.B., Le Bail, A., Thermal properties estimation during thawing via real-time neural network learning (2003) Journal OfFood Engineering, 57, p. 17Svozil, D., Kvasničva, V., Pospíchal, J., (1997) Chemometrics and Intelligent Laboratory Systems, 39, p. 43Dubé, M.A., Penlidis, A., A systematic approach to the study of multicomponent polymerization kinetics - The butyl acrylate /methyl methacrylate/vinyl acetate example: 1. Bulk Polymerization (1995) Polymer, 36, p. 587Févotte, G., Barudio, J., Guillot, J., An adaptive inferential measurement strategy for on-line monitoring of conversion in polymerization processes (1996) Thermochimica Acta, 289, p. 223Garson, G.D., Interpreting neural network connection weights (1991) Artificial Inteligence Expert, 6, p. 47Othman, N., Santos, A.M., Févotte, G., McKenna, T.F., Evaluation of emulsion polymerisation kinetics using non-linear state estimator (2000) Macromol. Symp., 150, pp. 109-11
The fluidized bed reactor with a prepolymerization system and its influence on polymer physicochemical characteristics
No full textThis work addresses the influence of a prepolymerization system on the behavior of the fluidized bed reactor used for polyethylene production. Its influence on the polymer's physicochemical characteristics and production was also studied. The results indicate that the use of prepolymerized catalyst particles results in milder temperatures in the fluidized bed reactor, thus avoiding the formation of hot spots, melting of the polymer particle and reactor shutdown. Productivity can be enhanced depending on the operational conditions used in the prepolymerization reactor.171179Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP
The fluidized bed reactor with a prepolymerization system and its influence on polymer physicochemical characteristics
No full textThis work addresses the influence of a prepolymerization system on the behavior of the fluidized bed reactor used for polyethylene production. Its influence on the polymer's physicochemical characteristics and production was also studied. The results indicate that the use of prepolymerized catalyst particles results in milder temperatures in the fluidized bed reactor, thus avoiding the formation of hot spots, melting of the polymer particle and reactor shutdown. Productivity can be enhanced depending on the operational conditions used in the prepolymerization reactor
Fluidized bed reactor for polyethylene production. The influence of polyethylene prepolymerization
No full textThis work addresses the influence of the prepolymerization of the catalyst particle on the fluidized bed reactor for polyethylene production. The influence of prepolymerization on the temperature and concentration gradients throughout the reactor was studied. The results obtained through simulations confirm industrial observations of the advantages of prepolymerization and extend these observation, showing the viable operational conditions for different superficial gas velocities and gas feeding temperatures as a function of the degree of prepolymerization
