Modeling and Simulation of Polymerization Processes

This reprint is a compilation of nine papers published in Processes, in a Special Issue on “Modeling and Simulation of Polymerization Processes”. It aimed to address both new findings on basic topics and the modeling of the emerging aspects of product design and polymerization processes. It provides a nice view of the state of the art with regard to the modeling and simulation of polymerization processes. The use of well-established methods (e.g., the method of moments) and relatively more recent modeling approaches (e.g., Monte Carlo stochastic modeling) to describe polymerization processes of long-standing interest in industry (e.g., rubber emulsion polymerization) to polymerization systems of more modern interest (e.g., RDRP and plastic pyrolysis processes) are comprehensively covered in the papers contained in this reprint

Modelling and validation of synthesis of poly lactic acid using an alternative energy source through a continuous reactive extrusion process

PLA is one of the most promising bio-compostable and bio-degradable thermoplastic polymers made from renewable sources. PLA is generally produced by ring opening polymerization (ROP) of lactide using the metallic/bimetallic catalyst (Sn, Zn, and Al) or other organic catalysts in a suitable solvent. In this work, reactive extrusion experiments using stannous octoate Sn(Oct)2 and tri-phenyl phosphine (PPh)3 were considered to perform ROP of lactide. Ultrasound energy source was used for activating and/or boosting the polymerization as an alternative energy (AE) source. Ludovic® software, designed for simulation of the extrusion process, had to be modified in order to simulate the reactive extrusion of lactide and for the application of an AE source in an extruder. A mathematical model for the ROP of lactide reaction was developed to estimate the kinetics of the polymerization process. The isothermal curves generated through this model were then used by Ludovic software to simulate the “reactive” extrusion process of ROP of lactide. Results from the experiments and simulations were compared to validate the simulation methodology. It was observed that the application of an AE source boosts the polymerization of lactide monomers. However, it was also observed that the predicted residence time was shorter than the experimental one. There is potentially a case for reducing the residence time distribution (RTD) in Ludovic® due to the ‘liquid’ monomer flow in the extruder. Although this change in parameters resulted in validation of the simulation, it was concluded that further research is needed to validate this assumption

Estratégias para a redução da concentração de catalisadores na polimerização radicalar por transferência de átomo : uma abordagem de estudo cinético por modelagem matemática e simulação

Orientador: Liliane Maria Ferrareso LonaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia QuímicaResumo: No contexto da Polimerização Radicalar por Desativação Reversível (RDRP), a associação do mecanismo de Regeneração de Ativador por Transferência de Elétrons (ARGET) à Polimerização Radicalar por Transferência de Átomos (ATRP) tem atraído atenção em termos de pesquisa, principalmente por ser um método de polimerização ambientalmente e economicamente mais favorável se comparada a ATRP convencional, devido à redução da concentração de catalisador verificada no processo. Pela escassez de registros em literatura, este trabalho tem como objetivo principal prover ferramentas matemáticas para simular a síntese de polímeros obtidos via ARGET ATRP, com a originalidade de contribuição voltada para a compreensão da cinética de reação de agentes redutores. Através de dados experimentais encontrados na literatura, dois modelos matemáticos propostos aplicados aos processos de homopolimerização e copolimerização aleatória via ARGET ATRP foram validados. A modelagem matemática desenvolvida é baseada no Método dos Momentos, sendo aplicado o Método Pseudocinético para o caso equivalente a copolimerização aleatória. No processo de validação realizado, constantes cinéticas, dentre aquelas que não se tem registros na literatura, foram ajustadas aos modelos através de algoritmo de otimização. Resultados fornecidos pela modelagem indicam que quanto maiores as concentrações iniciais de tanto do desativador quanto do agente redutor, maior a conversão de monômero, maior o peso molecular médio e menor a dispersividade. Simulações feitas também confirmam que a concentração inicial de desativador é um parâmetro crítico com maior sensibilidade do que a de agente redutor no processo ARGET ATRP em soluçãoAbstract: In the context of Reversible Deactivation Radical Polymerization (RDRP), the association of Activators Regenerated by Electron Transfer (ARGET) mechanism with the Atom Transfer Radical Polymerization (ATRP) has attracted attention in terms of research, mainly because it is an environmentally and economically more favorable polymerization method if compared to conventional ATRP, due to the catalyst concentration reduction verified in the process. By the scarcity of records in literature, this work has as main objective to provide mathematical tools to simulate the synthesis of polymers obtained by ARGET ATRP, with the originality of contribution focused on the comprehension of the reaction kinetics for the reducing agents. Through the experimental data found in the literature, two proposed mathematical models applied to the homopolymerization and random copolymerization processes via ARGET ATRP were validated. The mathematical modeling developed is based on the method of moments, being applied the method of pseudo-kinetic constants for the case equivalent to the random copolymerization process. In the model validation, kinetic constants, among those that have no records in the literature, were obtained by optimization algorithm. Results provided by the modeling indicate that the higher the initial concentrations of both deactivator and reducing agent, the monomer conversion, the higher the number-average molecular weight and the lower the dispersity. Simulations done also confirm that the initial concentration of deactivator is a critical parameter with higher sensitivity than the reducing agent in solution ARGET ATRP processMestradoEngenharia QuímicaMestre em Engenharia Química1725186CAPE

A Novel Nanoparticle Associated Polymer for Enhanced Oil Recovery in Harsh Conditions

Despite the high efficiency of polymer flooding as a chemical enhanced oil recovery (CEOR) technique, the low thermal stability and poor salt resistance of widely applied partially hydrolyzed polyacrylamide (HPAM) limited the application of this technique in oil reservoirs at harsh reservoir conditions of high–temperature and high–salinity (HTHS). These inadequacies of HPAM, result in the urge for environmentally friendly polymer with good viscosifying properties and a substantial effect on mobility ratio at HTHS reservoir condition. This research has introduced an assessment for the valorisation of a high acid value waste vegetable oil (WVO) into novel environmentally benign, thermo-responsive amphoteric nanocomposite for enhanced oil recovery (EOR) application at HTHS reservoir conditions. Two green reaction routes have been proposed to synthesize a novel oleic phenoxypropyl acrylate (OPA) thermosensitive monomer from high acid value WVO using different catalytic processes involve homogenous and heterogenous catalysts. A novel green copper-silica oxide/reduced graphene oxide (CuO-SiO2/RGO) multifunctional heterogeneous nanocatalyst derived from pomegranate peel extract has been synthesized and assessed for the direct conversion of high acid value WVO into OPA thermosensitive monomer via a single-step reaction. The prepared catalyst has been characterized using Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX). Response surface methodology (RSM) via Box-Behnken Design (BBD) has been utilized to derive the optimum OPA monomer yield at minimum reaction conditions for each reaction route, where the influence of the process variables and their interactions on the OPA yield has been evaluated. The reactive acryloyl double bond in the synthesized OPA monomer has been copolymerized with acrylamide (AM), acrylacyloxyethyltrimethyl ammonium chloride (DAC) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) in presence of dimethylphenylvinylsilane via free radical emulsion polymerization for the synthesis of a novel thermo-responsive amphoteric green polymer functionalized silica nanocomposite (AGPC) for EOR application at HTHS conditions. RSM based on central composite design (CCD) has been utilized to tailor-make the feed composition of the synthesized AGPC nanocomposite. Further, the synthesized AGPC has been extensively characterized by different techniques. The results indicated that the optimal conditions of OPA monomer synthesis using 4- (dimethylamino)pyridine (DMAP) homogenous catalyst have been developed at 2- hydroxy-3-phenoxypropyl acrylate to methyl ester (HPA:FAME) molar ratio of 7.8:1, reaction temperature of 45 ºC, catalyst loading of 1.72 % (w/w) in 5.8 hours reaction time for 92.6 % OPA yield. However, for OPA monomer synthesis using CuO-SiO2/RGO nanocatalyst the optimal conditions have been developed at hydroxy-3-phenoxypropyl acrylate to WVO (HPA:WVO) molar ratio of 7.8:1, catalyst loading of 2.5 % (w/w) and reaction temperature of 94 ºC in 9.5 hours for 95.6 % OPA yield. The synthesized nanocomposite solution exhibited a pouncing thermo-thickening behaviour and superior viscosifying properties even at ultra-low polymer concentration of 400 ppm as the temperature increased from 25 to 100 ºC, with increasing salinity from 10,000 to 230,000 mg.L-1TDS as well as salt-free solutions. The nanocomposite solutions exhibit high resistance factor (Rf) and residual resistance factor (Rrf) values of 11.61 and 7.88, respectively at a low polymer concentration of 1000 ppm which proves its ability to improve the sweeping efficiency. Flooding experiments demonstrated that oil recovery factor reached 15.4 %, 22.6 % and 25 % using low nanocomposite concentrations of 400 ppm, 600 ppm and 1000 ppm, respectively evaluated under hostile conditions of 100 ºC and a salinity about 230,000 mg.L-1TDS. Therefore, this research offers a new direction for the synthesis of a novel green, high molecular weight thermo-responsive nanocomposite for EOR application at extreme harsh reservoir conditions via WVO valorisation

Metal-Catalyzed Radical Polymerization up to High Pressure

The mechanism and kinetics of metal-catalyzed radical polymerization were investigated by spectroscopic means. A particular focus was set on Fe-mediated atom-transfer radical polymerization (ATRP) as there is a growing interest for an economic alternative to the extensively used Cu-mediated ATRP. Experiments were started with an iron bromide-based catalyst, which simply operates without any external ligands. FT-nearIR and Mössbauer spectroscopy were used to determine the structures of [Fe(II)Bru(Solv)v] and [Fe(III)Brw(Solv)x] complexes in a variety of solvents. It was found that the tetrahedral species [Fe(II)Br3(Solv)]− and [Fe(III)Br4]− essentially govern the activation−deactivation equilibrium of ATRP. The structure of these complexes is correlated with the measured ATRP activation rate coefficients, kact, and with the equilibrium constants, KATRP, for monomer-free model systems. In weakly polar solvents such as esters, ketones, and substituted benzenes, kact and also KATRP are up to two orders of magnitude higher than with strongly polar solvents, such as N-methylpyrrolidin-2-one (NMP), acetonitrile, and dimethylform-amide, where the [Fe(II)Br3(Solv)]− complex is more stabilized. Since further tuning of catalyst activity is important to access a wide range of monomers for ATRP, several types of Fe−ligand systems were tested for a potential enhancement of KATRP. The NIR spectroscopic analysis indicated that tetrahedral [Fe(II)BruLv]u+v=4 complexes also play a role with external ligands, L, such as N-heterocyclic carbenes and phosphines. However, these compounds do not significantly improve KATRP compared with solvent molecules being the ligands. Nevertheless, the studies were helpful to clarify the role of phosphines in ATRP. The highly Lewis basic tris(2,4,6-trimethoxy-phenyl)phosphine (TTMPP) may coordinate to Fe(II), but primarily acts as a reducing agent for [Fe(III)Br4]−, thus transforming TTMPP to TTMPP-Br+. Triphenylphosphine (TPP) is a less effective reducing agent. An enhanced KATRP was found for amine–bis(phenolate) iron complexes. A combined Mössbauer, EPR, NMR, and online VIS/NIR spectroscopic analysis was carried out to determine the relevant Fe species. An interplay between ATRP and organometallic-mediated radical polymerization (OMRP), which is based on the reaction of propagating radicals with Fe(II), may occur depending on the monomer under investigation. Styrene polymerization operates via ATRP, whereas an interplay between ATRP and OMRP occurs for MMA polymerization. The kinetics of ATRP and OMRP were quantitatively measured by highly time-resolved EPR spectroscopy in conjunction with pulsed-laser application for radical production, i.e., the so-called SP–PLP–EPR method. ATRP deactivation of methacrylate-type radicals by an amine–bis(phenolate)iron catalyst was monitored without interference by organometallic reactions. Toward higher temperatures, the ratio of deactivation to propagation rate increases, which is beneficial for ATRP control. SP–PLP–EPR was also applied to quantify the catalytic termination (CRT) of two propagating radicals by Fe(II) via an organometallic intermediate. In case of the [Fe(II)Br3(Solv)]− catalyst, the organometallic reaction plays a role for acrylate rather than for methacrylate polymerization, where CRT is by about three orders of magnitude slower. As a consequence, ATRP of acrylates should be carried out with low levels of the Fe(II) catalyst to avoid CRT and thus improve the living character of ATRP. The investigations into metal-catalyzed radical polymerization were expanded up to pressures of 6000 bar. Applying pressure results in a redistribution of iron bromides in favor of the charged species [FeBr4]2− and [Fe(Solv)6]2+, which is particularly pronounced in polar solvents such as NMP or acetonitrile. As a consequence, the reaction volume, ΔrV(KATRP), is positive for [Fe(II)Xu(Solv)v] catalysts (up to 18 cm3 mol−1). The studies demonstrated the advantage of the well-defined amine–bis(phenolate)iron system: ΔrV(KATRP) is negative, (−17 ± 2) cm3 mol−1, which is associated with a favorable shift of the ATRP equilibrium toward the side of the activated radical. Along with the increase in propagation rate, ATRP rate is thus enhanced by more than two orders of magnitude between 1 and 6000 bar. ATRP also benefits from an improved living character under high pressure, which is due to the lowering of diffusion-controlled termination. This facilitates the synthesis of polystyrenes and polyacrylates with molar masses above 100,000 g mol−1 and dispersities below 1.29 under either Fe or Cu catalysis. These advantages were not compromised by an increase in the rate of intramolecular transfer, i.e., the backbiting reaction during acrylate polymerization under high pressure, which was deduced from modeling the ATRP experiments. This thesis has improved the understanding of the mechanism and kinetics of Fe-mediated ATRP, in particular, of the potential interplay with OMRP. Moreover, the studies provide guidance for the selection of suitable reaction conditions that yield predominantly ATRP-mediated polymerizations with improved control.2016-09-0

A Model-Based Framework for the Smart Manufacturing of Polymers

It is hard to point a daily activity in which polymeric materials or plastics are not involved. The synthesis of polymers occurs by reacting small molecules together to form, under certain conditions, long molecules. In polymer synthesis, it is mandatory to assure uniformity between batches, high-quality of end-products, efficiency, minimum environmental impact, and safety. It remains as a major challenge the establishment of operational conditions capable of achieving all objectives together. In this dissertation, different model-centric strategies are combined, assessed, and tested for two polymerization systems. The first system is the synthesis of polyacrylamide in aqueous solution using potassium persulfate as initiator in a semi-batch reactor. In this system, the proposed framework integrates nonlinear modelling, dynamic optimization, advanced control, and nonlinear state estimation. The objectives include the achievement of desired polymer characteristics through feedback control and a complete motoring during the reaction. The estimated properties are close to experimental values, and there is a visible noise reduction. A 42% improvement of set point accomplishment in average is observed when comparing feedback control combined with a hybrid discrete-time extended Kalman filter (h-DEKF) and feedback control only. The 4-state geometric observer (GO) with passive structure, another state estimation strategy, shows the best performance. Besides achieving smooth signal processing, the observer improves 52% the estimation of the final molecular weight distribution when compared with the h-DEKF. The second system corresponds to the copolymerization of ethylene with 1,9-decadiene using a metallocene catalyst in a semi-batch reactor. The evaluated operating conditions consider different diene concentrations and reaction temperatures. Initially, the nonlinear model is validated followed by a global sensitivity analysis, which permits the selection of the important parameters. Afterwards, the most important kinetic parameters are estimated online using an extended Kalman filter (EKF), a variation of the GO that uses a preconditioner, and a data-driven strategy referred as the retrospective cost model refinement (RCMR) algorithm. The first two strategies improve the measured signal, but fail to predict other properties. The RCMR algorithm demonstrates an adequate estimation of the unknown parameters, and the estimates converge close to theoretical values without requiring prior knowledge

Analysis of rheological properties and molecular weight distributions in continuous polymerization reactors

This work explores the possibility of exploiting structure-property relationships to manufacture tailor-made polymers with target end-use properties. A novel framework which aims to improve upon current industrial practices in polymerization process and product quality control is proposed. The strong inter-relationship between the molecular architecture and rheological properties of polymers is the basis of this framework. The melt index is one of the most commonly used industrial measures of a polymer's processibilty. However, this single-point non-Newtonian viscosity is inadequate to accurately reflect the polymer melt's flow behavior. This justifies monitoring the entire viscosity-shear rate behavior during the polymerization stage. In addition, the crucial role played by the polymer melt's elastic characteristics is not reflected in it's shear viscosity and so elasticity meaurements are also warranted. In this study, rheological models available in the open literature are utillized to demonstrate these critical issues at industrially relevant operating conditions. The observations made are also compared with published experimental results and found to be qualitatively similar. Two case studies are presented. The first one is the free-radical solution polymerization of styrene with binary initiators in a cascade of two CSTRs. In the second case, the solution polymerization of ethylene in a single CSTR with a mixture of two single-site transition metal catalysts is considered. The feasibility of the proposed framework to tailor the product's MWD, irrespective of the underlying reactor configuration or kinetic mechanism, is demonstrated via steady state simulations. Relative gain analysis reveals the non-linearity and interactions in the control loops. Although the main contributions of this study primarily deal with the viscoelastic behavior of linear homopolymers, potential extensions to systems involving polymers with small amounts of long chain branching or the control of other end-use properties are also discussed