scholarly journals Modeling and optimization of ethylene copoplymerization in high pressure reactor using difunctional initiators

2021 ◽  
Author(s):  
Pegah Khazraei Karimi Fard
Keyword(s):  
Molecular Weight ◽  
High Pressure ◽  
Free Radical ◽  
Average Molecular Weight ◽  
Tubular Reactor ◽  
Monomer Conversion ◽  
Optimization Method ◽  
Reactivity Ratio ◽  
Reactor Model ◽  
Control Variables

Free radical (co-)polymerization of low-density polyethylene (LDPE) is carried out commonly in high pressure autoclaves or tubular reactors. The severe thermodynamic conditions of the process hinder ethylene from going to full conversion. One remedy to improve the monomer conversion is to investigate the effectiveness of initiators, such as difunctional organic peroxides. In the present work, a kinetic model based on a postulated reaction mechanism for free radical ethylene (co-) polymerization initiated by difunctional initiators is applied to analyze the dynamic behavior of a continuous LDPE isothermal autoclave reactor and a non-isothermal tubular reactor. The model describes the rates of initiation, propagation and the population balance equations. It predicts variations of the initiator and monomer concentrations and reaction temperature as well as molecular weight distribution of reactive macromolecular species. Variations of the pressure, velocity and transport/physical properties of the reacting mixture were accounted for in the tubular reactor. Model predictions are compared to experimental data collected from literatures for one monofunctional (dioctanoyl) and two difunctional initiators namely, (2,2-bis(tert-butylperoxy)-butane and 2.5-dimetyl hexane-2t-butylperoxy-5perpivalate). In comparison with dioctanoyl peroxide, polymerization with difunctional initiators requires a lesser amount of initiators and gives higher ethylene conversion in a shorter time. The modeling of LSPE with difunctional initiators was then extended to ethylene copolymerization with vinyl acetate and butyl acrylate. The model helps to determine the influence of reactivity ratio on the end-use product properties. Details of modeling a multiple feed LSPE tubular reactor are included for both homo- and co-polymerization reactions. The effect of monomer and initiator injections on the productivity and (co)polymer rheology and composition are investigated as well. Finally, an optimization method was applied to determine the optimal values of control variables via maximization of an objective function expressed in terms of monomer conversion, number average molecular weight, polydispersity and final desired composition of copolymer product. The results show that we can obtain a polymer with desired characteristics by proper manipulation of the control variables.

scholarly journals Modeling and optimization of ethylene copoplymerization in high pressure reactor using difunctional initiators

2021 ◽  
Author(s):  
Pegah Khazraei Karimi Fard
Keyword(s):  
Molecular Weight ◽  
High Pressure ◽  
Free Radical ◽  
Average Molecular Weight ◽  
Tubular Reactor ◽  
Monomer Conversion ◽  
Optimization Method ◽  
Reactivity Ratio ◽  
Reactor Model ◽  
Control Variables

Free radical (co-)polymerization of low-density polyethylene (LDPE) is carried out commonly in high pressure autoclaves or tubular reactors. The severe thermodynamic conditions of the process hinder ethylene from going to full conversion. One remedy to improve the monomer conversion is to investigate the effectiveness of initiators, such as difunctional organic peroxides. In the present work, a kinetic model based on a postulated reaction mechanism for free radical ethylene (co-) polymerization initiated by difunctional initiators is applied to analyze the dynamic behavior of a continuous LDPE isothermal autoclave reactor and a non-isothermal tubular reactor. The model describes the rates of initiation, propagation and the population balance equations. It predicts variations of the initiator and monomer concentrations and reaction temperature as well as molecular weight distribution of reactive macromolecular species. Variations of the pressure, velocity and transport/physical properties of the reacting mixture were accounted for in the tubular reactor. Model predictions are compared to experimental data collected from literatures for one monofunctional (dioctanoyl) and two difunctional initiators namely, (2,2-bis(tert-butylperoxy)-butane and 2.5-dimetyl hexane-2t-butylperoxy-5perpivalate). In comparison with dioctanoyl peroxide, polymerization with difunctional initiators requires a lesser amount of initiators and gives higher ethylene conversion in a shorter time. The modeling of LSPE with difunctional initiators was then extended to ethylene copolymerization with vinyl acetate and butyl acrylate. The model helps to determine the influence of reactivity ratio on the end-use product properties. Details of modeling a multiple feed LSPE tubular reactor are included for both homo- and co-polymerization reactions. The effect of monomer and initiator injections on the productivity and (co)polymer rheology and composition are investigated as well. Finally, an optimization method was applied to determine the optimal values of control variables via maximization of an objective function expressed in terms of monomer conversion, number average molecular weight, polydispersity and final desired composition of copolymer product. The results show that we can obtain a polymer with desired characteristics by proper manipulation of the control variables.

scholarly journals Initiator Feeding Policies in Semi-Batch Free Radical Polymerization: A Monte Carlo Study

Processes ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1291 ◽  
Author(s):  
Ali Seyedi ◽  
Mohammad Najafi ◽  
Gregory T. Russell ◽  
Yousef Mohammadi ◽  
Eduardo Vivaldo-Lima ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Monte Carlo ◽  
Free Radical ◽  
Methyl Methacrylate ◽  
Radical Polymerization ◽  
Average Molecular Weight ◽  
Free Radical Polymerization ◽  
Monte Carlo Algorithm ◽  
Single Shot ◽  
The Impact

A Monte Carlo simulation algorithm is developed to visualize the impact of various initiator feeding policies on the kinetics of free radical polymerization. Three cases are studied: (1) general free radical polymerization using typical rate constants; (2) diffusion-controlled styrene free radical polymerization in a relatively small amount of solvent; and (3) methyl methacrylate free radical polymerization in solution. The number- and weight-average chain lengths, molecular weight distribution (MWD), and polymerization time were computed for each initiator feeding policy. The results show that a higher number of initiator shots throughout polymerization at a fixed amount of initiator significantly increases average molecular weight and broadens MWD. Similar results are also observed when most of the initiator is added at higher conversions. It is demonstrated that one can double the molecular weight of polystyrene and increase its dispersity by 50% through a four-shot instead of a single shot feeding policy. Similar behavior occurs in the case of methyl methacrylate, while the total time drops by about 5%. In addition, policies injecting initiator at high monomer conversions result in a higher unreacted initiator content in the final product. Lastly, simulation conversion-time profiles are in agreement with benchmark literature information for methyl methacrylate, which essentially validates the highly effective and flexible Monte Carlo algorithm developed in this work.

scholarly journals Photocrosslinkable polymer based on 4-(3-(2,4-dichlorophenyl)-3-oxoprop-1-enyl) phenylacrylate: synthesis, reactivity ratio, and crosslinking studies

2016 ◽  
Vol 34 (4) ◽  
pp. 834-844 ◽  
Author(s):  
J. Suresh ◽  
S. Karthik ◽  
A. Arun
Keyword(s):  
Molecular Weight ◽  
Average Molecular Weight ◽  
Decomposition Temperature ◽  
Reactivity Ratio ◽  
Solution Polymerization ◽  
Acryloyl Chloride ◽  
Acrylate Monomer ◽  
Step Process

AbstractThe acrylate monomer was synthesized by two step process. 2,4-dichloro-1-ene(4-hydroxyphenyl)phenone (DHP) was synthesized using 4-hydroxy benzaldehyde and 2,4-dichloro acetophenone. 4-[3-(2,4-dichloro-phenyl)3-oxoprop-1-en-1-yl]phenylacrylate (DCP) was prepared by reacting DHP with acryloyl chloride. The synthesized monomer was copolymerized with 2-hydroxyethyl acrylate and styrene using solution polymerization technique. Monomer and polymers were characterized by IR, NMR and UV techniques. The average molecular weight of the polymer was around 4000 g/mol. First and second decomposition temperature of the polymers was around 320 °C and 430 °C, respectively. The reactivity ratio of the polymers was calculated by Fineman-Ross, Kelen-Tudos and extended Kelen-Tudos methods. The synthesized monomer has been less reactive than the commercial monomer. The rate of photocrosslinking increased from 39 % to 99 % due to the using of copolymerization technique.

Synthesis and Characterization of well Defined Polychloroprene by RAFT Polymerization

2013 ◽  
Vol 787 ◽  
pp. 241-244
Author(s):  
Jia Hui ◽  
Yan Shi ◽  
Zhi Feng Fu
Keyword(s):  
Molecular Weight ◽  
Raft Polymerization ◽  
Average Molecular Weight ◽  
Reaction Times ◽  
Monomer Conversion ◽  
H Nmr ◽  
Molecular Weight Distributions ◽  
Reversible Addition ◽  
Raft Agent ◽  
Active Nature

Well defined polychloroprene has been synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization with 2-(ethoxycarbonyl) prop-2-yl dithiobenzoate (EPDTB) as RAFT agent, AIBN as initiator, Chloroprene as monomer. Polymerization with two different feed ratios of monomer to RAFT agent were carried out. The sampling products at different reaction times were characterized using GPC and 1H-NMR. The GPC results demonstrated the molecular weight distributions (Mw/Mn) were narrow, and the number average molecular weight (Mn) was developed linearly with monomer conversion. All the characteristic signals of polychloroprene with the EPDTB as terminal groups were clearly observed in the 1H-NMR spectrum. In addition, the chain-extended polymers were also obtained successfully using the macro-RAFT agent, which indicated the active nature of the chain end.

Advanced Modelling for Investigating the Effects of Reactor Operation on Controlled Living Emulsion Polymerization

2009 ◽  
Vol 4 (3) ◽  
Author(s):  
Vincent G Gomes ◽  
Ibrahem S Altarawneh ◽  
Mourtada H Srour
Keyword(s):  
Molecular Weight ◽  
Particle Size ◽  
Emulsion Polymerization ◽  
Average Molecular Weight ◽  
Polymeric Materials ◽  
Monomer Conversion ◽  
Batch Mode ◽  
Reversible Addition ◽  
Monomer Feed ◽  
Experimental Protocols

Accurate control of product properties through the manipulation of transfer agents can be of great benefit to industry in producing targeted polymeric materials. In this work we developed experimental protocols and mathematical models for understanding and characterising semi-batch emulsion polymerization in the presence of a xanthate-based transfer agent. Zero-one kinetics was employed with population balance equations to predict monomer conversion, molecular weight (MWD) and particle size (PSD) distributions in the presence of xanthate-based reversible addition-fragmentation chain transfer (RAFT) agents. The effects of the transfer agent (AR), surfactant, initiator (KPS) and temperature were investigated. Monomer feed rate was found to strongly affect conversion, MWD and PSD. The polymerization rate (Rp), number average molecular weight (Mn) and particle size () decreased with increasing AR. Rp increased with increase in SDS and KPS; while with increase in temperature, Mn decreased, Rp increased and increased. With semi-batch mode, Mn and increased with monomer flow rate.

Atom transfer radical polymerization of styrene initiated by the novel initiator 2-bromo-2-nitropropane

e-Polymers ◽  
2005 ◽  
Vol 5 (1) ◽  
Author(s):  
Gang Wang ◽  
Xiulin Zhu ◽  
Cheng Zhengping ◽  
Jian Zhu
Keyword(s):  
Molecular Weight ◽  
Atom Transfer Radical Polymerization ◽  
Radical Polymerization ◽  
Average Molecular Weight ◽  
Monomer Conversion ◽  
Catalyst System ◽  
Chain Extension ◽  
Atom Transfer ◽  
The Novel ◽  
H Nmr

AbstractHeterogeneous atom transfer radical polymerization (ATRP) of styrene initiated by 2-bromo-2-nitropropane in bulk was carried out with CuCl/2,2′-bipyridine as the catalyst. The kinetics was first order in monomer and the numberaverage molecular weight of the polymer increased linearly with monomer conversion, indicating the ‘living’/controlled nature of the polymerization. However, the number-average molecular weight was usually higher than the theoretical one. The nitro group might react with the Cu complex, resulting in insufficient initiation. The amount of catalyst has no effect on the controllability of this catalyst system for the ATRP of styrene. The presence of a halide end group in the obtained polymer was confirmed by both 1H NMR and chain-extension reaction.

The Characteristic Research of Two Kinds of Block Polymer

2011 ◽  
Vol 356-360 ◽  
pp. 74-77
Author(s):  
Qing Bo Yu ◽  
Xian Hua Li ◽  
Yu Lun Tao ◽  
Guo Jun Cheng
Keyword(s):  
Molecular Weight ◽  
Free Radical ◽  
Methyl Acrylate ◽  
Diblock Copolymers ◽  
Triblock Copolymers ◽  
Glycidyl Ether ◽  
Monomer Conversion ◽  
Block Polymer ◽  
Allyl Glycidyl Ether ◽  
Living Free Radical Polymerization

Dual end and single end MacroRAFT agents of polystyrene were obtained respectively by polymerizations of styrene in the presence of benzyl 1H-imidazole-1- carbodithioate (BICDT) and 4,4‘-bis(imidazole-1-carbodithioatemethyl)biphenyl (ICTMP) via the thermal initiation. Then copolymerization of allyl glycidyl ether（AGE） with methyl acrylate（MA） was performed to prepare the functional block copolymers in the presence of PSt maeorRATF agents. The results show that the process has good characteristics of living free radical polymerization. However, the top monomer conversion of triblock copolymers comparing diblock copolymers is lower under the same theory molecular weight and the content of monomer.

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