Solution Polymerization Of Methyl Methacrylate Research Articles

Modeling of a solution polymerization reactor operating in semi-batch mode for polymethyl methacrylate production

The severe consequences of thermal runaways, make process optimization of paramount importance for free radical polymerization reactors, in order to maximize in an integrated way their safety and productivity. Generally, this optimization is performed by simulation, for the sake of safety and cost. Today, the literature contains several models of free radical polymerization reactors in general; and methyl methacrylate (MMA) polymerization reactors, in particular. Although, MMA polymerization is commonly performed in semi-batch reactors at industrial level, most of the available models focus on batch reactors; while, the semi-batch reactor models are much scarcer. In this work, a model of a MMA solution polymerization batch reactor was modified in order to generalize it to semi-batch operation. The developed semi-batch model was used here for studying the effect of different operation conditions (feeding flow rate, initiator load, monomer initial load, and reactor temperature) on the quality characteristics of the produced polymer and on the safety and productivity of the polymerization reactor. The developed model can be used to optimize the operation conditions of a semi-batch reactor so that the final product quality meets the application requirements, while maintaining the reactor within its safe-operation envelope, and maximizing its productivity.

Thermal safety and overall kinetics for methyl methacrylate solution polymerization via on-line process analytical technology

Polymethyl methacrylate (PMMA) is widely used, but its polymerization process is highly hazardous and the relevant thermal hazards have not been adequately investigated. Herein, the thermal safety and kinetic mechanisms of methyl methacrylate (MMA) polymerization are explored. The effect of monomer concentration on the exothermic characteristics is first investigated using a reaction calorimeter. The results indicate that the exothermic behavior of this reaction is significantly influenced by the monomer concentration. Meanwhile, a quantitative relationship between the specific enthalpy and monomer concentration is determined. Moreover, overall rate expression is developed by a rapid quantitative method to further elucidate the quantitative dependence of reaction rate on the process conditions. Subsequently, adiabatic experiment is performed to reveal the thermal controllability of this reaction. Finally, risk level is ascertained to propose constructive countermeasures. This work provides guidance for the safe operation of MMA polymerization, and the methodology also furnishes universal solutions for analogous reactions.

편광자 지지체를 위한 투명도가 높은 In situ 공중합 강화 PMMA 고분자

In this study, a series of poly(methyl methacrylate) (PMMA) copolymer films were prepared via solution polymerization of methyl methacrylate (MMA) with butyl acrylate (BA) and lauryl methacrylate (LMA) as monomers. Mechanical properties, hydrophobic properties, and optical properties of the films were intensively investigated. The rheological results showed that the fluidity of the copolymer was considerably enhanced. When the monomer ratio of MMA:BA:LMA was 100:30:10, the copolymer film S4 showed the best overall performance with perfect optical transparency maintained. The results of the dynamic mechanical and thermal analysis suggested that the glass transition temperature (TSUBg/SUB) moved towards lower temperature, with enhanced ductility of the PMMA films. A large number of yield folds and crazes appeared on the cross-sectional surface of copolymer films through morphological observations, displaying the obvious characteristics of toughness fracture and obeying the energy dissipation mechanism of cracks shear band. The present study provided a facile way of preparing PMMA films with high toughness and light transmittance by appropriate selection of the monomers, which will be of practical significance for further studies on the replacement of triacetyl cellulose as a support film of polarizers.

Influence of ferrocene on the solution polymerization of methyl methacrylate

Kinetic study of the methyl methacrylate solution polymerization in the presence of ferrocene in solvents, differing in polarity (benzene, toluene, ethyl acetate) has been carried out. It is shown that the speed of the process is significantly increased and activation energy of polymerization falls largely in the presence of ferrocene. The influence of the polarity of the medium on the kinetic parameters of the process is traced. The largest increase in speed and drop in activation energy of polymerization observed in the most polar ethyl acetate. Keywords: methyl methacrylate; ferrocene; solution polymerization; solvent polarity.

Development of compartment model for inhibition of thermal runaway in free-radical polymerization

Shortstopping reactions via injection of chemical inhibitors is a promising technique of emergency response to prevent thermal runaway, with unique advantages of cost effectiveness and process sustainability over current evacuation practices. However, computational modeling of the inhibition process for ensuring successful designs remains challenging. In this paper, a compartment model is developed to investigate the design of the inhibition system with detailed characterization in both complex kinetic mechanism and nonideal mixing effect. The reactor volume is divided into a network-of-zones (NoZ), with each zone modeled as a well-mixed reactor. The free-radical solution polymerization of methyl methacrylate (MMA) in a stirred batch reactor is used as a demonstrative example. The flow parameters and network structure of compartment models are validated with the CFD simulation. The developed compartment models are employed to investigate interactions of poor mixing and exothermic chemistry that lead to thermal runaway and key design factors including injection location, quantity, kinetic requirement, and timing on the effectiveness of quenching thermal runaway.

Controllable surface-initiated metal-free atom transfer radical polymerization of methyl methacrylate on mesoporous SBA-15 via reductive quenching

The surface-initiated metal-free atom transfer radical polymerization (ATRP) solution polymerization of methyl methacrylate was carried out for the first time on the basis of the reductive quenching mechanism. In this study, the 2-bromoisobutyryl bromide (BiBB) was anchored on the surface of self-synthesized rod-like mesoporous material SBA-15 as the initiator, with the commercially available organic dye fluorescein (FL) as photocatalyst and triethylamine (TEA) as electron donor under the irradiation of blue lamp. The obtained composites and polymers were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, N2 adsorption/desorption measurements, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and gel permeation chromatography. The results demonstrated that the ordered mesoporous structure of SBA-15 was not disrupted after the polymerization. With an increase in illumination time, the grafting amount and the number average molecular weight of poly(methyl methacrylate) (PMMA) on the surface of SBA-15 linearly increased, and the molecular weight distribution (Đ) widened. PMMA with a relatively narrow Đ value was obtained after polymerization for 10 h (1.47). The increase in the grafting amount and molecular weight after chain extension confirmed the chain end functionality of PMMA grafted on SBA-15.

Investigation of RAFT polymerization in mesoporous SBA-15 by using various monomers

Reversible addition fragmentation transfer (RAFT) polymerization has attracted much attention, because its reaction mechanism has been well studied and it provides a facile approach to prepare the special functional polymer. Herein, mesoporous SBA-15 with pore size of 6 nm was employed as a “microreactor” for the RAFT solution polymerization of methyl methacrylate (MMA), glycidyl methacrylate (GMA) or styrene (St) using a xanthate as a chain transfer agent and AIBN as the initiator. The structures, morphologies and properties of the obtained polymers and in-situ composites were fully characterized. XPS results confirm the presence of sulfur in the obtained polymers, which indicates a RAFT polymerization mechanism. XRD observation found that the in-situ composites exhibited the similar two-dimensional hexagonal pore structures intrinsic to SBA-15. However, the specific surface area, pore size, and pore volumes of the composites decreased dramatically compared with the intrinsic SBA-15 morphology. N2 adsorption studies of polymers synthesized from various monomer mixtures revealed differing properties with adsorption capacity in the order of GMA > MMA > St. The Mn and Mw of polymers produced from within SBA-15 were significantly higher than those produced external to the SBA-15 framework. Meanwhile, the molecular weight distributions of polymers constructed within the SBA-15 were narrower. Lastly, the thermal stability and glass transition temperature of the polymers constructed within the SBA-15 were notably enhanced.

Reversible-deactivation Radical Solution Polymerization of Methyl Methacrylate Catalyzed by Tetrabutylammonium Iodide†

Reversible-deactivation Radical Solution Polymerization of Methyl Methacrylate Catalyzed by Tetrabutylammonium Iodide†

Reversible complexation mediated polymerization (RCMP)–solution polymerization of methyl methacrylate catalyzed by Bu4N+I− (BNI) with in-situ formed alkyl iodide initiator

ABSTRACTThe reversible complexation mediated polymerization (RCMP) of methyl methacrylate catalyzed by tetrabutylammonium iodide (BNI) was performed in toluene with an alkyl iodide initiator in situ formed. The influence of BNI amount, polymerization temperature, solvent, and initiator on the polymerization was studied. Results showed that the more organic catalyst, higher reaction temperature, highly polar solvent, and higher activity initiator led to shorter inhibition period and faster polymerization. More importantly, the mechanism for the shorter inhibition period and faster polymerization with BNI was proposed:Poly(methyl methacrylate) with predetermined molar mass and relatively low Mw/Mn (determined by size exclusion chromatography, SEC) was successfully synthesized. Furthermore, the structure of resulting polymers was characterized using 1H NMR The living/controlled feature of the polymers was further demonstrated by the chain extension experiment. Attractive features of this procedure include commercially available catalyst, ease of operation, and efficiency.

Solution Polymerization of Methyl Methacrylate in an Ionic Liquid Employing Cyclic Multifunctional Initiators

1‐Butyl‐3‐methylimidazolium tetrafluoroborate ([BMIM][BF4]) was used as a solvent during the methyl methacrylate polymerization, in a temperature range of 110 to 130°C, employing two multifunctional cyclic peroxides as initiators, the pinacolone diperoxide and the diethylketone triperoxide, and results were compared with those obtained in N,N‐dimethylformamide (DMF) as a solvent under the same reaction conditions. The polymerization rate was approximately four times faster in [BMIM][BF4] than in DMF, and this behavior is supported by the higher decomposition rate constants calculated for both initiators in pure ionic liquid in comparison with those calculated in DMF. The average molecular weights values were nearly three times lower in DMF than in the ionic liquid, and this is explained by the reduction in the propagation activation energy in the presence of the ionic liquid.

Modeling of Methyl Methacrylate Polymerization Using MATLAB

Abstract This paper presents a modeling of methyl methacrylate (MMA) polymerization with toluene in the presence of azo-bi’s-isobutyronitrile (AIBN) using MATLAB. This work aims to optimize the initial concentration of initiator and the reactor temperature to achieve a maximum monomer conversion in minimum batch time. The optimization of solution polymerization of MMA based on the three-stage polymerization model (TSPM) was performed using ode23t solver. The non-linear polymerization kinetics considered the gel, glass and cage effect to obtain a realistic prediction. The predicted reactor and jacket temperature showed a reasonable agreement with the experimental data, where the error is about 2.7 % and 2.3 %, respectively. The results showed that a maximum monomer conversion of 94 % was achieved at 0.126 kgmol m–3 of the initial concentration of AIBN and 346 K of the initial reactor temperature in 8,951 s (2.5 h).

Combining On-Line Characterization Tools with Modern Software Environments for Optimal Operation of Polymerization Processes

This paper discusses the initial steps towards the formulation and implementation of a generic and flexible model centric framework for integrated simulation, estimation, optimization and feedback control of polymerization processes. For the first time it combines the powerful capabilities of the automatic continuous on-line monitoring of polymerization system (ACOMP), with a modern simulation, estimation and optimization software environment towards an integrated scheme for the optimal operation of polymeric processes. An initial validation of the framework was performed for modelling and optimization using literature data, illustrating the flexibility of the method to apply under different systems and conditions. Subsequently, off-line capabilities of the system were fully tested experimentally for model validations, parameter estimation and process optimization using ACOMP data. Experimental results are provided for free radical solution polymerization of methyl methacrylate.

Effect of Multiorganomodified LiAl‐ or MgAl‐Layered Double Hydroxide on the PMMA Nanocomposites

ABSTRACTHerein we investigated new type of poly(methyl methacrylate) (PMMA) nanocomposites by solution polymerization of methyl methacrylate (MMA) in the presence of multimodified Layer double hydroxide (LDHs). Two different anionic exchange capacities LiAl and MgAl types of LDHs were used and modified with cocoamphodipropionate (K2) and sodium dodecyl sulfate by the anionic ion exchange method. The modified and pure LDHs have been characterized by X‐ray diffraction (XRD), and Fourier transform infrared spectroscopy. Solution‐polymerized PMMA nanocomposite LDH dispersion morphology was investigated by transmission electron microscopy and XRD. Thermo‐mechanical, gas barrier, and optical clarity properties of nanocomposite systems are greatly improved relative to the virgin PMMA.

Synthesis of poly(methyl methacrylate) and block copolymers by semi-batch nitroxide mediated polymerization

The limits of control of the molecular weight and polymer structure in the semi-batch solution polymerization of methyl methacrylate by NMP are explored.

Thermal degradation of transparent poly(methyl methacrylate)/silica nanoparticle hybrid films

Using thermogravimetric (TG/DTG) analysis, we evaluated the thermal degradation characteristics of transparent poly(methyl methacrylate) (PMMA)/silica nanoparticle hybrid films obtained by well dispersing surface-unmodified silica (SiO2) nanoparticles, of average particle size approximately 15 nm, in poly(methyl methacrylate), of weight-average molecular weight (Mw) 9.6 × 104 as synthesized by radical solution polymerization of methyl methacrylate (MMA). The TG/DTG curve of a secondary aggregated opaque hybrid film, comprising SiO2 nanoparticles of size greater than several hundreds of nanometers, was in substantial agreement with that of pure PMMA. What was surprising, however, was that in the transparent hybrid, weight reduction due to cleavage of head-to-head bonds in PMMA occurring around 200 °C was nearly completely absent, and DTG peaks originating from cleavage of head-to-tail bonds and allylic-position cleavage of terminal vinylidene double bonds increased. These thermal degradation behaviors can be explained by the hypothesis of a specific chemical reaction between tertiary terminal macroradicals produced by cleavage of head-to-head bonds and silanol (SiOH) on the SiO2 nanoparticle surface.

Parametric Studies on the Grafting of Poly(Methyl Methacrylate) onto Organophilic Montmorillonite Using Silylated Clay Platelets

Poly(methyl methacrylate) (PMMA)/organophilic montmorillonite (Cloisite 30B) nanocomposites were synthesized by the chemical grafting of PMMA onto Cloisite 30B via solution polymerization of methyl methacrylate (MMA) with vinyl-modified organoclay. The effects of different parameters such as clay weight percent (CWP), solvent per monomer volume ratio, and dispersion time on the properties of the PMMA grafted Cloisite 30B were investigated using the Taguchi experimental design method. This method gives a much-reduced variance for the experiments with optimum setting of control parameters and provides a set of minimum experiments compared to the conventional methods. Qualitative evidence for the chemical grafting of the PMMA onto Cloisite 30B was confirmed by Fourier transform infrared spectroscopy (FT-IR). X-ray diffraction (XRD) was used to investigate interlayer changes of the clay in the grafted nanoplatelets. The exfoliated/intercalated morphology of the nanocomposites was confirmed by XRD. Furthermore, thermal properties were measured by thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMTA). Statistical analysis of results revealed that clay weight percent and solvent per monomer ratio had significant effects on the properties of final products. The percent of grafted PMMA and storage modulus of PMMA/30B nanocomposites decreased with increasing clay content due to better dispersion of the clay at lower loadings. On the other hand, because of a tendency to formation of homopolymer and oligomers at higher solvent loadings; the percent of grafted PMMA, storage modulus and glass transition temperature of PMMA/30B nanocomposites decreased with an increase in solvent per monomer volume ratio. However, the obtained PMMA/30B nanocomposites at the optimum conditions, was exhibited a higher glass transition temperature, higher storage modulus and better thermal stability than the pure PMMA.

Cu2 +-templated self-assembly of an asymmetric Salen–Cu(II) complex and its application in catalytic polymerization of methyl methacrylate (MMA)

With the mono-imine HL (HL=(E)-2-((2-aminophenylimino)methyl)-4,6-di-tert-butyl-phenol) as the precursor, an asymmetric Salen-type Schiff-base complex [Cu(L2)] (3, H2L2=2-((E)-2-((E)-2-hydroxybenzylideneamino)phenylimino)methyl-4,6-di-tert-butylphenol) was obtained by Cu2+-templated approach in the presence of salicylaldehyde due to the formation of intermediate {[Cu(L)(OAc)]}2 (2)2. In contrast to the inertness for 2/AIBN system (AIBN=azobis(isobutyronitrile)), both the symmetric and asymmetric Salen-type Schiff-base complexes [Cu(L1)] (1, H2L1=N, N′-bis(3,5-di-tert-butyl-salicylidene)phenylene-1,2-diamine) and [Cu(L2)] (3) as the catalysts in the presence of AIBN could effectively catalyze the solution polymerization of MMA (MMA=methyl methacrylate) for the formation of the syndio-enriched PMMAs, where the steric and the electronic effects of the ligands play an important and influential role on the catalytic behaviors, while on the premise of controllable polymerizations the variation of polymerization conditions almost has no effect on the polymer tacticity.

Use of CFD in modeling MMA solution polymerization in a CSTR

A computational fluid dynamics (CFD) model was developed to study methyl methacrylate (MMA) solution polymerization in a lab-scale stationary continuous stirred tank reactor (CSTR) equipped with a six bladed 45° pitched impeller. Azobisisobutyronitrile (AIBN) and ethyl acetate were taken as the initiator and solvent, respectively. The CFD modeling approach incorporated an integration of the continuity, momentum, and species transport equations along with a polymerization source term. The latter was a function of thermal and chemical initiations, transfer to monomer and solvent as well as the gel effect. Multiple reference frame (MRF) technique, laminar regime, and isothermal condition were considered in the modeling. To validate the CFD model, the simulation results of conversion in a stationary CSTR of MMA polymerization were compared with the data reported in the literature. The CFD model was then employed to investigate the impacts of the impeller speed, reaction temperature, residence time and inlet monomer (or solvent) concentration on the conversion and homogeneity of reaction mixture inside the reactor. Contours of monomer mass fraction conceptually facilitated to visualize the reaction progress in the reactor.

Tracking Offline Conversion Solution Polymerization of Methyl Methacrylate / Vinyl Acetate in Toluene in a Reactor Calorimeter

Analyses systems by chromatography in gaseous phase and by gravimetric have been used for the offline follow-up of the conversion of monomers during the copolymerization in solution of methyl methacrylate (MMA) and vinyl acetate (AVc) conducted in the calorimetric reactor (batch). In the present work, an empirical model was generated using of the calibration curve connecting the spectral data CPG to the measured conversion by gravimetric. The obtained calibration was characterized by a correlation coefficient of 99.57%. The rate of conversion of MMA (83%) is higher compared to AVc (26%) according to the rate of reactivity (rMMA = 26 and rAVc = 0.0319). The results obtained by gravimetric and CPG are well adapted for the follow-up of the polymerization reaction.

Nonlinear Multiple Model Predictive Control of Solution Polymerization of Methyl Methacrylate

A sequential linearized model based predictive controller is designed using the DMC algorithm to control the temperature of a batch MMA polymerization process. Using the mechanistic model of the polymerization, a parametric transfer function is derived to relate the reactor temperature to the power of the heaters. Then, a multiple model predictive control approach is taken in to track a desired temperature trajectory.The coefficients of the multiple transfer functions are calculated along the selected temperature trajectory by sequential linearization and the model is validated experimentally. The controller performance is studied on a small scale batch reactor.