Polymerization Processes, 1. Fundamentals

Tobita, Hidetaka

doi:10.1002/14356007.a21_305.pub3

Cited by 16 publications

(9 citation statements)

References 114 publications

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“…For usual bulk polymerization, [R • ] is determined from the balance of initiation rate R I and termination rate R t under stready state, with R I = R t = k t [R • ] 2 , leading to obtain:

where k t is the termination rate constant. Note that the convention of termination rate, R t = k t [R • ] 2 that does not involve the coefficient 2 is used ([ 1 ], p. 12).…”

Section: Introductionmentioning

confidence: 99%

Effect of Small Reaction Locus in Free-Radical Polymerization: Conventional and Reversible-Deactivation Radical Polymerization

Tobita

2016

Polymers

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Abstract:When the size of a polymerization locus is smaller than a few hundred nanometers, such as in miniemulsion polymerization, each locus may contain no more than one key-component molecule, and the concentration may become much larger than the corresponding bulk polymerization, leading to a significantly different rate of polymerization. By focusing attention on the component having the lowest concentration within the species involved in the polymerization rate expression, a simple formula can predict the particle diameter below which the polymerization rate changes significantly from the bulk polymerization. The key component in the conventional free-radical polymerization is the active radical and the polymerization rate becomes larger than the corresponding bulk polymerization when the particle size is smaller than the predicted diameter. The key component in reversible-addition-fragmentation chain-transfer (RAFT) polymerization is the intermediate species, and it can be used to predict the particle diameter below which the polymerization rate starts to increase. On the other hand, the key component is the trapping agent in stable-radical-mediated polymerization (SRMP) and atom-transfer radical polymerization (ATRP), and the polymerization rate decreases as the particle size becomes smaller than the predicted diameter.

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“…For usual bulk polymerization, [R • ] is determined from the balance of initiation rate R I and termination rate R t under stready state, with R I = R t = k t [R • ] 2 , leading to obtain:

where k t is the termination rate constant. Note that the convention of termination rate, R t = k t [R • ] 2 that does not involve the coefficient 2 is used ([ 1 ], p. 12).…”

Section: Introductionmentioning

confidence: 99%

Effect of Small Reaction Locus in Free-Radical Polymerization: Conventional and Reversible-Deactivation Radical Polymerization

Tobita

2016

Polymers

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“…As a result of the nanosized reaction locus, there is a physical segregation of radicals inside each particle, prohibiting two radical species from reacting by the isolation of radicals inside each particle; this effect is called compartmentalization. , Thus, the monomer droplets do not behave like bulk polymerization microsystems. A limited number of radicals can exist inside a polymer particle, and the average particle radical number, n̅ , is the result of the interplay among radical entry, desorption, bimolecular termination, and chain transfer . There are representative models to account for the compartmentalization, e.g., the zero-one model and the pseudobulk model. ,, …”

Section: Mechanism Of Aam Inverse Miniemulsion Polymerizationmentioning

confidence: 99%

Mathematical Modeling of Inverse Miniemulsion Polymerization of Acrylamide with an Oil-Soluble Initiator

Giudici

Colmán

Giudici

2021

Ind. Eng. Chem. Res.

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A model is proposed for the inverse miniemulsion polymerization of acrylamide (AAm) with an oil-soluble initiator. The model is based on the assumptions that (1) polymerization occurs in both the continuous phase and the polymer particles; (2) the radicals in the continuous phase with length that exceeds z crit can enter the monomer droplets; (3) a limited number of radicals can exist inside the polymer particles; (4) small radicals can exit the polymer particles; and (5) propagation is diffusion-controlled at high conversions. The model predictions of conversion, particle number, and the occurrence of a diffusion-controlled propagation reaction at high conversions were validated by comparison with experimental data for inverse miniemulsion polymerization, showing good agreement. The occurrence of diffusion-controlled propagation ("glass effect") at high conversions is also discussed and additionally validated with literature data.

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“…In free-radical polymerization, the weight-based CLD of the primary chains whose birth conversion is x = θ is given by the following equation. [6,14]…”

Section: Primary Chain Length Distribution and Average Chain Lengthmentioning

confidence: 99%

“…The instantaneous number-average P np and weight-average P wp chain length of primary chains are given respectively by [6,14] τ…”

Section: Primary Chain Length Distribution and Average Chain Lengthmentioning

confidence: 99%

Effect of Branch Point Distribution on the Radius of Gyration in Batch Free‐Radical Polymerization with Chain Transfer to Polymer

Tobita

2020

Macro Theory & Simulations

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Free-radical polymerization is irreversible, and the primary chains formed earlier are expected to possess larger branching density compared with those formed later, leading to a branching density distribution (BDD) among primary chains. In addition to the BDD, the primary chain length distribution (CLD) may change during polymerization. For a primary CLD with a shift toward smaller chain length during polymerization, the expected g-ratio for a given number k of branch points can be approximated reasonably well with that for the random branched polymers having the accumulated primary CLD. On the other hand, when the primary CLD moves toward larger chain length during polymerization, the expected g-ratio may become smaller than the corresponding random branched polymers, due to an "unnatural" combination in the length of backbone and branch chains. The compactness of branched architecture could be controlled through the consideration of the maximum end-to-end path length.

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Polymerization Processes, 1. Fundamentals

Abstract: The article contains sections titled: 1. Introduction 2. Polymerization Mechanisms and Kinetics 3. Kinetics of Step Polymerization … Show more

Cited by 16 publications

References 114 publications

Effect of Small Reaction Locus in Free-Radical Polymerization: Conventional and Reversible-Deactivation Radical Polymerization

Effect of Small Reaction Locus in Free-Radical Polymerization: Conventional and Reversible-Deactivation Radical Polymerization

Mathematical Modeling of Inverse Miniemulsion Polymerization of Acrylamide with an Oil-Soluble Initiator

Effect of Branch Point Distribution on the Radius of Gyration in Batch Free‐Radical Polymerization with Chain Transfer to Polymer

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