Simulation of Free Radical High‐Pressure Copolymerization in a Multizone Autoclave: Model Development and Application

Ghiass, Majid; Hutchinson, Robin A.

doi:10.1081/pre-120026882

Cited by 28 publications

(22 citation statements)

References 26 publications

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“…Because of the very low reactivity of ethylene, free-radical polymerization of ethylene and copolymerization of ethylene with polar monomer require harsh reaction conditions (high ethylene pressures: 250−3000 bar, and high temperatures: 150−375 o C) either in an autoclave reactor or in a tubular. [17][18][19] Moreover, the polymer architectures obtained are branched and poorly defined such as commercial low density polyethylene (LDPE) and ethylene-vinyl acetate copolymer (EVA). Recent improvements (< 250 bar, < 100 o C) on these issues via controlled radical polymerization techniques are appealing, but molecular weights (M n ) of polymers are still low, which are less than 10 5 g mol -1 and usually 10 3 -10 4 g mol -1 .…”

Section: Introductionmentioning

confidence: 99%

Facile Access to Polar-Functionalized Ultrahigh Molecular Weight Polyethylene at Ambient Conditions

Kang

Zhang

et al. 2022

CCS Chem

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Direct copolymerization of ethylene with polar monomers to produce polar functionalized polyethylene is the most straightforward and potentially ideal route. However, access to high molecular weights of polar copolymers represents one of the biggest challenges. In this contribution, we report a family of well-designed nickel catalysts that readily address the issue at convenient and highly desired ambient conditions. Under 1 bar at 30 o C, polar functionalized ultrahigh number-average molecular weight polyethylenes (UHMWPE, M n = 825~1102 kg mol -1 ) can directly be generated. The highest average number of incorporated polar units per polymer chain is 122. This enhances copolymer molecular weights with up to two orders of magnitude relative to previous reports. Notably, this nickel catalyst family also exceptionally produces the highest number-average molecular weight polyethylenes (M n = 6037 kg mol -1 ) at 1 bar using the nickel species. The Sterimol B 1 steric parameter of nickel catalyst quantitatively correlates to polymer molecular weight. Mechanistic insights from DFT calculation reveal that the low barrier (10.4 kcal mol -1 ) of ethylene insertion as the rate-limiting step should be responsible for high activity and the formation of UHMWPE. This coordination-insertion approach is strikingly contrast to the high energy free-radical approach.

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Section: Introductionmentioning

confidence: 99%

Facile Access to Polar-Functionalized Ultrahigh Molecular Weight Polyethylene at Ambient Conditions

Kang

Zhang

et al. 2022

CCS Chem

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“…EVA copolymers are industrially manufactured by high pressure free radical polymerization in either autoclave or tubular reactors. [8][9][10][11][12][13][14] Unlike EVA resins that are flexible, tough, and clear suitable for food packaging and photovoltaic encapsulants and sheets, VAE emulsion contains smaller amount of ethylene and used in different applications from EVA resins. The current study is on the semibatch emulsion and miniemulsion copolymerization of VAc and ethylene to VAE copolymer.…”

Section: Introductionmentioning

confidence: 99%

“…Another type of ethylene‐VAc copolymer is called ethylene vinyl acetate copolymer (EVA) where the ethylene is the major constituent and its content ranges from 60%–90%. EVA copolymers are industrially manufactured by high pressure free radical polymerization in either autoclave or tubular reactors 8–14 . Unlike EVA resins that are flexible, tough, and clear suitable for food packaging and photovoltaic encapsulants and sheets, VAE emulsion contains smaller amount of ethylene and used in different applications from EVA resins.…”

Section: Introductionmentioning

confidence: 99%

High pressure semibatch emulsion and miniemulsion copolymerization of vinyl acetate and ethylene

Narayanan

Choi

2020

J of Applied Polymer Sci

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This study presents the experimental study of semibatch emulsion and miniemulsion copolymerization of vinyl acetate (VAc) and ethylene to vinyl acetate-ethylene (VAE) copolymer at 60 C and 80-300 psig. In the miniemulsion copolymerization, a water-soluble initiator (K 2 S 2 O 8) is used and VAc miniemulsion is prepared in presence of surfactant and cosurfactant using a sonicator or a high-shear homogenizer. Then, ethylene gas is supplied to the reactor at constant partial pressure. In a miniemulsion process, the mass transfer limitations of VAc from monomer droplets to the aqueous phase, and to micelles or polymer latex particles that are present in conventional macro-emulsion polymerization can be eliminated and the transfer of ethylene dissolved in the aqueous phase to the miniemulsion droplets is the major ethylene transport process for the polymerization. The experimental data show that the amount of ethylene incorporation into the copolymer is higher in miniemulsion polymerization than in emulsion polymerization. The ethylene pressure has been found to have a strong impact on the ethylene incorporation into the copolymer phase in both emulsion and miniemulsion copolymerizations but the increase is more pronounced in miniemulsion case. The VAE copolymer latex particles prepared by miniemulsion polymerization exhibited higher storage stability than those prepared by macro-emulsion polymerization.

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“…Even though the production process and the properties of LDPE have been studied for decades, due to their complexity, there are still important aspects of the relationships between process conditions, structure and properties that are not yet well understood, especially when the material is produced in multizone autoclave reactors (MZAR) for which few works were found in the literature despite their industrial prevalence . On the other hand, it is known that the physical and performance properties of LDPE largely depend on its molecular weight distribution (MWD) and long‐chain branching distribution (BD) …”

Section: Introductionmentioning

confidence: 99%

“…MZAR are frequently used in industry because they provide more degrees of freedom to tailor‐shape the MWD than a single zone reactor. In spite of this, to our knowledge, this is one the first papers in which the description of the full MWD in an MZAR is addressed; in previous (few) papers, only averages of the MWD are modeled or, in the best case, the information provided is not detailed or not precise . There are some publications by Neuhaus as well as Eckes focusing on multizone reactors including the calculation of the MWD with the support of the commercial software PREDICI.…”

Section: Introductionmentioning

confidence: 99%

Mathematical Modeling of the Molecular Weight Distribution in Low Density Polyethylene. I. Steady‐State Operation of Multizone Autoclave Reactors

López‐Carpy

Saldívar‐Guerra

Zapata‐González

et al. 2018

Macro Reaction Engineering

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this polymer a unique molecular structure containing long-chain branches (LCB) that confer very special shear and extensional rheological behavior to the material. [1] Even though the production process and the properties of LDPE have been studied for decades, due to their complexity, there are still important aspects of the relationships between process conditions, structure and properties that are not yet well Conflict of InterestThe authors declare no conflict of interest.

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Simulation of Free Radical High‐Pressure Copolymerization in a Multizone Autoclave: Model Development and Application

Cited by 28 publications

References 26 publications

Facile Access to Polar-Functionalized Ultrahigh Molecular Weight Polyethylene at Ambient Conditions

Facile Access to Polar-Functionalized Ultrahigh Molecular Weight Polyethylene at Ambient Conditions

High pressure semibatch emulsion and miniemulsion copolymerization of vinyl acetate and ethylene

Mathematical Modeling of the Molecular Weight Distribution in Low Density Polyethylene. I. Steady‐State Operation of Multizone Autoclave Reactors

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