Macromolecular Reaction Engineering

Cover image for Vol. 8 Issue 8

Special Series: Sensors, Process Control and Modeling in Polymer Production

Guest-edited by Jose R. Leiza, this series publishes in an on-going fashion invited articles by leading researchers to document the rapid progress in this field.

 

Monitoring Polymerization Kinetics in Microreactors by Confocal Raman Microscopy

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Arvind Kumar Yadav, Manfred Krell, Wolf-Dieter Hergeth, José Carlos de la Cal and María Jesús Barandiaran*

Use of confocal Raman microscopy to monitor kinetics of homogeneous and heterogeneous polymerizations in microreactors is being reported. The adequacy of the technique is demonstrated through several experiments performed at different residence time for solution and miniemulsion polymerizations. The method also allows getting the conversion evolution along the microreactor length by changing the position of the Raman microscope.

Macromol. React. Eng. DOI: 10.1002/mren.201300193

 

Filtrodynamics 2 - Effects of Particle Size and Filter Type on Trans-Filter Time-Dependent Pressure Signals

sensors_7_1_Reed.jpgMarie Dufrechou, Emmanuel Mignard, Michael F. Drenski and Wayne F. Reed*

The filtrodynamic behavior of trans-filter time-dependent pressure signals is determined for membrane and frit filters using latex spheres of varying diameter D. An accretion model based on Darcy's law best describes the mechanism of membrane filters. Non-membrane metallic frits reveal a different mechanism and behavior of filtration that is better described by the "characteristic loading" model.

Macromol. React. Eng. DOI: 10.1002/mren.201300185

 

Robust Calorimetric Estimation of Semi-Continuous and Batch Emulsion Polymerization Systems with Covariance Estimation

sensors_6_8_Le_Roux.jpgFranklin D. Rincón, Marcelo Esposito, Pedro Henrique Hermes de Araújo, Fernando V. Lima and Galo A. C. Le Roux*

Moving horizon estimation is an optimization-based filter that can address non-linear and constrained systems. A monitoring procedure with statistical parameters estimated by the autocovariance least-squares technique is proposed and validated with experimental emulsion polymerization reaction data. The estimation results are compared with gravimetric analysis and the effect of the initial estimate is also evaluated, showing that the procedure is robust.

Macromol. React. Eng. DOI: 10.1002/mren.201300151

 

Filtrodynamics: Time Dependent Trans-Filter Pressure Signals for Early Detection and Monitoring of Particulates During Chemical Processing

sensors_6_7_Reed.jpgClaiton Brusamarello, Michael F. Drenski, Artem Isakov and Wayne F. Reed*

The formation of unwanted particulate aggregates, which must be filtered out of the product stream, is a common problem in polymer production and other industrial processes. In filtrodynamics, the feasibility of using a network of inline filters and trans-filter pressure signals as an inexpensive, rugged, continuous process monitoring method is examined, and particle-filter interaction models are proposed.

Macromol. React. Eng. DOI: 10.1002/mren.201300152

 

Single-Point Intrinsic Viscosity and Density Measurements for In-Line MIMO Control Purposes of a Lumped-Distributed Polymeric System

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Márcia P. Vega,* Ernanda Bellumat, Enrique L. Lima, José Carlos Pinto*

Much information is provided by the leading moments of the molecular weight distributions such as Mw. A simple viscometrical method for in-line monitoring of Mw in solution polymerizations is employed. In-line multivariable conversion and control of weight-average molecular weight in a tubular reactor polymerization unit is implemented.

Macromol. React. Eng. DOI: 10.1002/mren.201200041

 

Modeling of Polymer Network Formation from Preformed Precursors

sensors_6_11_Dusek.jpgKarel Dušek,* Miroslava Dušková-Smrčková*

Precursors of crosslinked polymeric materials are pre-prepared from small molecules and are characteristic of distributions of composition, molecular weights, number, type, and reactivity of functional groups. These distributions depend on the history of precursor formation and affect the structure and properties of the final network

Macromol. React. Eng. DOI: 10.1002/mren.201200028

 

Quantum Chemical Investigation of Secondary Reactions in Poly(vinyl chloride) Free-Radical Polymerization

sensors_6_8_2_Moscatelli.jpgDanilo Cuccato, Marco Dossi, Davide Moscatelli,* Giuseppe Storti

Vinyl chloride polymerization is investigated using quantum chemical methods, with emphasis on the reactions involving mid-chain radicals (MCRs). A kinetic model accounting for such reactions is developed to elucidate their impact on the final polymer properties. The contribution of backbiting reactions is relevant in determining the radical migration along the chains.

Macromol. React. Eng. DOI: 10.1002/mren.201200010

 

Detailed Microstructure Investigation of Acrylate/Methacrylate Functional Copolymers by Kinetic Monte Carlo Simulation

sensors_6_8_1_Leiza.jpgShaghayegh Hamzehlou, Yuri Reyes, Jose R. Leiza*

The architecture of acrylate/methacrylate functional copolymers is studied by MC simulation in homogeneous media in batch and semibatch reactors. Detailed information on the complex structures of these branched polymers can be extracted. Branching density and functional monomer composition as a function of chain length can be easily determined.

Macromol. React. Eng. DOI: 10.1002/mren.201200016

 

Reaction Monitoring of Glycerol Step-Growth Polymerization Using ATR-FTIR Spectroscopy

sensors_6_2-3_n_Dube.jpgSomaieh Salehpour, Marc A. Dubé*

Step-growth polymerization of glycerol is monitored using three different techniques: water production monitoring, hydroxyl value calculation, and ATR-FTIR spectroscopy. In-line or off-line ATR-FTIR spectroscopy is a successful method for monitoring the reaction up to medium conversion and for monitoring composition in polyglycerol hydrogel production.

Macromol. React. Eng. DOI: 10.1002/mren.201100071

 

A QM Approach to the Calculation of Reactivity Ratios in Free-Radical Copolymerization

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Marco Dossi, Davide Moscatelli*

In a free-radical copolymerization the reactivity of each monomer pair is characterized by suitable reactivity ratios. To support the experimental activity monomer and radical reactivity ratios are calculated through an approach based on quantum chemistry. A collection of totally computational reactivity ratios for a variety of copolymer is showed proving the potentiality of the proposed tool.

Macromol. React. Eng. DOI: 10.1002/mren.201100065

 

A Continuous-Flow Polymerization Microprocess with Online GPC and Inline Polymer Recovery by Micromixer-Assisted Nanoprecipitation

sensors_5_11-12_n_Serra.jpgFlorence Bally, Christophe A. Serra,* Cyril Brochon, Nicolas Anton, Thierry Vandamme, Georges Hadziioannou

A complete continuous-flow microprocess is developed starting from a monomer solution and ending with a colloidal suspension of polymer nanoparticles, including online polymer characterization. Polymethacrylates are synthesized in a microreactor and analyzed online by GPC. The polymer solution is finally nanoprecipitated with the use of a micromixer, which enables to get size-adjustable nanoparticles.

Macromol. React. Eng. DOI: 10.1002/mren.201100047

 

Semibatch Aqueous-Solution Polymerization of Acrylic Acid: Simultaneous Control of Molar Masses and Reaction Temperature

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Roque J. Minari, Gerardo Caceres, Paola Mandelli, Mariana M. Yossen, Manuel Gonzalez-Sierra, Jorge R. Vega, Luis M. Gugliotta*

The semibatch aqueous-solution polymerization of acrylic acid was reported. The proposed strategy has probed to be able to control the molar masses of the produced polyacrylic acid under safe conditions and it could be interesting for industrial applications.

Macromol. React. Eng. DOI: 10.1002/mren.201000059

 

The Consumption of Oxygen and p-Methoxyphenol in Acrylic Acid - Kinetics and Modeling

sensors_5_5-6_n_Brand_.jpgRaphael H. Brand, A. Hartwig, B. Opitz, C. Pfeifer, A. Drochner, G. Herbert Vogel*

Acrylic acid is a high reactive substance; therefore, the handling needs a lot of know-how and experience. To guarantee a save handling it is necessary to understand the stabilizer interactions during the inhibition period. In the current work, we were able to introduce an enhanced stabilization mechanism based on kinetic data and stability investigations. Via a mathematical model these mechanism could be proofed.

Macromol. React. Eng. DOI: 10.1002/mren.201000057

 

In-Line Monitoring of Particle Size during Emulsion Polymerization under Different Operational Conditions using NIR Spectroscopy

sensors_5_3-4_n_Giudici.jpgDennis L. Chicoma, Claudia Sayer, Reinaldo Giudici*

Effects of light scattering by polymer particles affects some spectral regions of the NIR spectra collected in-line during emulsion polymerization. Appropriate calibration models can be obtained to relate the NIR spectra with the values of the average particle size (measured off-line by DLS), thus allowing the online monitoring of particle size during the polymerization.

Macromol. React. Eng. DOI: 10.1002/mren.201000049

 

In-Line Monitoring of Emulsion Polymerization Reactions Combining Heat Flow and Heat Balance Calorimetry

sensors_4_11_n_de_Araujo.jpgMarcelo Esposito, Claudia Sayer, Pedro Henrique Hermes de Araújo*

In-line monitoring of semi-batch vinyl acetate emulsion polymerizations was performed combining heat flow and heat balance calorimetry to re-estimate the overall heat transfer coefficient between the reactor and jacket. The initial UARJ was obtained applying a constant power through an electrical heater to the initial reactor charge. As UARJ changed during the reaction, it was re-estimated combining the mass and energy balances of the jacket and the reactor and minimizing an objective function in terms of TJ_out. Results showed that good in-line estimations of conversion can be performed without requiring the use of experimental conversion data to re-estimate UARJ during the reaction.

Macromol. React. Eng. DOI: 10.1002/mren.201000026

 

Advanced Monitoring and Control of Multi-monomer System in Emulsion Polymerization

sensors_4_11_n_Gomes.jpgVincent G. Gomes

A constrained model predictive control (MPC) was developed based on a multi-layer monitoring and regulatory system for emulsion polymerization of multiple monomers with batch and with semi-batch operation. Our design basis comprised mechanistic models for the multi-phase, multi-stage process for implementing the control of conversion, particle size, molar mass, and polymer composition using multi-platform software environment coordination. Experimental tests showed the achievement of desired objectives with good robustness and without violating the process constraints. Improvements in the process operation and product property control were noted on implementing the developed multi-variable MPC.

Macromol. React. Eng. DOI: 10.1002/mren.201000023

 

Modeling Controlled/Living Radical Polymerization Kinetics: Bulk and Miniemulsion

sensors_4_11_n_Tobita.jpgHidetaka Tobita

Polymerization kinetics of various types of controlled/living radical polymerization (CLRP) is discussed in a unified manner. On the basis a characteristic rate expression unique to CLRP, the effect of nanosized reaction locus (<100 nm) on the polymerization kinetics is clarified. The threshold particle diameter Dp, below which the polymerization rate starts to increase or decrease, can be determined quantitatively. Some of the key equations are shown in the figure.

Macromol. React. Eng. DOI: 10.1002/mren.201000029

 

Nitroxide-Mediated Radical Polymerization of Butyl Acrylate Using TEMPO: Improvement of Control Exploiting Nanoreactors?

sensors_4_11_n_Zetterlund.jpgPer B. Zetterlund

TEMPO-mediated acrylate polymerization is known to be problematic, speculated to be related to excessive accumulation of free TEMPO as well as the activation rate being too low in relation to the propagation rate. The present theoretical results indicate that it may be possible to at least partially overcome these difficulties by careful exploitation of compartmentalization effects in nanoreactors.

Macromol. React. Eng. DOI: 10.1002/mren.201000022

 

In-Line Monitoring of Vinyl Chloride Suspension Polymerization with Near Infrared Spectroscopy, 2 - Design of an Advanced Control Strategy

sensors_4_8_2_Pinto.jpgJoão Miguel de Faria Jr., Fabricio Machado, Enrique Luis Lima, José Carlos Pinto*

Near infrared spectroscopy (NIRS) is used for in-line monitoring of particle morphology in PVC suspension polymerizations. Calibration models are used as references for control. As modification of operation variables during the batch leads to modification of the final morphological properties of the powder, advanced NIR-based control procedures can be implemented for control of morphological properties of PVC resins, as illustrated through simulation.

Macromol. React. Eng. DOI: 10.1002/mren.201000013

 

Fundamental Measurements in Online Polymerization Reaction Monitoring and Control with a Focus on ACOMP

sensors_4_8_1_Reed.jpgAlina M. Alb, Wayne F. Reed*

Fundamental measurements of quantities related to polymerization reactions made online can provide a quantitative and comprehensive picture of the reaction as it evolves. ACOMP is a platform for integrating several fundamental measurements, such as light scattering, viscosity, refractive index, and UV/Visible/IR spectroscopy. Several recent advances in the area are reviewed.

Macromol. React. Eng. DOI: 10.1002/mren.200900079

 

Development of Advanced Software Tools for Computer-Aided Design, Simulation, and Optimization of Polymerization Processes

sensors_4_5_1_Kiparissides.jpgApostolos Krallis, Prokopis Pladis, Vassileios Kanellopoulos, Costas Kiparissides*

Recent developments regarding a new generation of software packages for the simulation, parameter and state estimation and optimization of polymerization processes are presented. The new software tools provide a user-friendly interface, including an object-oriented programming environment allowing the integration of advanced mathematical models from different sources in an easy and comprehensive way.

Macromol. React. Eng. DOI: 10.1002/mren.200900053

 

Online Monitoring of Polyolefin Particle Growth in Catalytic Olefin Slurry Polymerization by Means of Lasentec Focused Beam Reflectance Measurement and Video Microscopy Probes

sensors_4_1_2_Muelhaupt.jpgRainer Xalter, Rolf Mülhaupt*

Polymer particle growth in catalytic ethylene slurry polymerizations with SiO2-supported metallocene and post-metallocene catalysts was monitored online using a Lasentec FBRM probe inserted into the stirred reactor. FBRM enabled the online monitoring of particle numbers and size distributions. Trend analyses provided time-resolved information on selected variables of the particle growth processes. FBRM was combined with simultaneous ethylene mass flow measurements in order to distinguish between ideal particle growth and more complex growth processes involving particle fragmentation and aggregation. Additional use of a Lasentec PVM video microscopy probe during ethylene polymerization on a MgCl2-supported Ziegler catalyst enabled the online visualization of PE particles, complementing the data generated by FBRM online monitoring.

Macromol. React. Eng. DOI: 10.1002/mren.200900048

 

In-Line Monitoring of Vinyl Chloride Suspension Polymerization with Near-Infrared Spectroscopy, 1 - Analysis of Morphological Properties

sensors_4_1_1_Pinto.jpgJoão Miguel de Faria Jr., Fabricio Machado, Enrique Luis Lima, José Carlos Pinto*

It is demonstrated that during suspension polymerizations it is possible to monitor morphological characteristics of PVC resins such as bulk density, cold plasticizer absorption and average particle diameter in-line and in real time using NIR spectroscopy. NIR spectra are obtained at different experimental conditions, showing that the spectra are sensitive to changes in the PVC properties. Standard mathematical procedures (partial least squares regression) are used to build empirical models and correlate the morphological properties with the obtained NIR spectra, allowing for monitoring of the PVC morphology in-line and in real time.

Macromol. React. Eng. DOI: 10.1002/mren.200900035

 

Modeling of Molecular Transfer in Heterophase Polymerization

sensors_3_7_3_Tauer.jpgHugo F. Hernández, Klaus Tauer*

Mass transfer across interfaces greatly determines the kinetics of heterophase polymerization. All molecules in the system can cross any interface as long as they possess enough energy to overcome barriers such as interfacial tension, chemical potentials, etc. Two main groups of mathematical approaches have been used to model mass transfer: macroscopic deterministic and molecular stochastic. Macroscopic modeling may use fundamental laws, thermodynamic expressions and empirical or semi-empirical equations. Molecular models are based on the discrete character of nature and include stochastic simulation, BD or MD. Special emphasis is placed on the most relevant molecular transfer processes observed in free-radical emulsion polymerization.

Macromol. React. Eng. DOI: 10.1002/mren.200900016

 

A Critical Overview of Sensors for Monitoring Polymerizations

sensors_3_7_2_Dube.jpgGabriela E. Fonseca, Marc A. Dubé*, Alexander Penlidis

The available on-line and in-line sensor technologies developed for polymerization reactors from 1990 until today are discussed and critically reviewed. About 600 references are included, which evidence the growth in sensor technology in the last two decades. Sensors for operational parameters in polymer reactors (i.e. temperature, pressure, level and flow) as well as sensors for polymer property monitoring (i.e. calorimetry, chromatography and spectroscopy, among others) are included. Complementary topics such as state estimation, multivariate statistical methods, fault diagnosis techniques and optimal sensor selection and location are briefly covered.

Macromol. React. Eng. DOI: 10.1002/mren.200900024

 

Special Article Series on 'Sensors, Process Control and Modeling in Polymer Production'

sensors_3_7_1_Leiza.jpgJose R. Leiza

Polymers are product-by-process whose microstructure, and hence application properties, are mostly determined in the reactor. Therefore, the understanding of the processes occurring in the reactor is crucial to achieve an efficient, consistent, safe and environmentally-friendly production of polymer materials with improved performance. This requires the development of detailed and predictive mathematical models of the polymerization processes, accurate and robust monitoring techniques and optimization and control strategies.

Guest-edited by Jose R. Leiza (University of the Basque Country, San Sebastian), the new article series "Sensors, Process Control and Modeling in Polymer Production" will highlight the most important developments and trends in this field.

Macromol. React. Eng. DOI: 10.1002/mren.200900045

 

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