Transition into the gel regime for free radical crosslinking polymerisation in a batch reactor

Chemical Engineering Science

Iedema

2015

Self Cite

Transition into the gel regime for crosslinking radical polymerisation in a continuously stirred tank reactor Kryven, I.; Iedema, P.D. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Download date: 13 May 2018Transition into the gel regime for crosslinking radical polymerisation in a continuously stirred tank reactor

Section: Contribution Of Termination Mechanismsmentioning

confidence: 52%

Section: Reaction Mechanismsmentioning

confidence: 99%

“…An algorithm for designing the coefficient population balance for crosslinking reaction mechanisms is discussed in details in [21].…”

Section: Approximation Schemementioning

confidence: 99%

Section: Evolution Of Multiradicalsmentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Transition into the gel regime for crosslinking radical polymerisation in a continuously stirred tank reactor

Chemical Engineering Science

Iedema

2015

Self Cite

Random Graph Approach to Multifunctional Molecular Networks

Macromol. Theory Simul.

Duivenvoorden

Hermans

et al. 2016

one must realize that such simulations imply an enormous spread of length and time scales: even the simple case of a linear polymer exhibits geometrical structures from the scale of a chemical bond to the scale of the gyration radius, to the collective length scales that might be much larger in dense materials. [ 1 ] Moreover, our drive for modelling is not limited to linear polymers but also is directed at tree-like branched structures, cross-linked polymers, and even infinite molecular networks, i.e., gels. In this paper we propose a strategy that draws a consensus between what can be computed on the one hand and pursuing fundamental roots of the matter at hand on the other.The process of assembly or polymerization of molecular networks usually goes through a few temporal stages: disconnected monomers, linear polymer, branched polymer, and gel (an infi nite network). Furthermore, the gel itself should not be perceived as a single, fi nal state of polymer topology. After the gel point the connectivity patterns of the network continue to evolve. [2][3][4] In fact, in many cases a major part of the whole polymerization process may occur in the gel regime. [ 5 ] In view of extremely long time scales associated with polymerization, namely, the time scales that might well exceed hours for some industrial processes, [ 6 ] or even years (drying of oil paint [ 7 ] ), direct atomistic simulation Formation of a molecular network from multifunctional precursors is modelled with a random graph process. The process does not account for spatial positions of the monomers explicitly, yet the Euclidean distances between the monomers are derived from the topological information by applying self-avoiding random walks. This allows favoring reactivity of monomers that are close to each other, and to disfavor the reactivity for monomers obscured by the surrounding. As a result, the model is applicable to large time scales. The phenomena of conversion-dependent reaction rates, gelation, microgelation, and structural inhomogeneity are predicted by the model. Resulting nonhomogeneous network topologies are analyzed to extract such descriptors as: size distribution, crosslink distances, and gel-point conversion. Furthermore, new to the molecular simulation community descriptors are suggested that are especially useful when explaining evolution of the gel as being a single molecule: local clustering coeffi cient, network modularity, cluster size distribution.

Acrylate Network Formation by Free‐Radical Polymerization Modeled Using Random Graphs

Schamboeck

Macro Theory & Simulations

Iedema

2017

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A novel technique is developed to predict the evolving topology of a diacrylate polymer network under photocuring conditions, covering the low‐viscous initial state to full transition into polymer gel. The model is based on a new graph theoretical concept being introduced in the framework of population balance equations (PBEs) for monomer states (mPBEs). A trivariate degree distribution that describes the topology of the network locally is obtained from the mPBE, which serves as an input for a directional random graph model. Thus, access is granted to global properties of the acrylate network which include molecular size distribution, distributions of molecules with a specific number of crosslinks/radicals, gelation time/conversion, and gel/sol weight fraction. Furthermore, an analytic criterion for gelation is derived. This criterion connects weight fractions of converted monomers and the transition into the gel regime. Valid results in both sol and gel regimes are obtained by the new model, which is confirmed by a comparison with a “classical” macromolecular PBE model. The model predicts full transition of polymer into gel at very low vinyl conversion (<2%). Typically, this low‐conversion network is very sparse, as becomes apparent from the predicted crosslink distribution.