Based on a recently suggested reaction mechanism, which involves the production and propagation of terminal double bonds (TDBs), kinetic models for the polymerization of N‐vinylpyrrolidone in aqueous solution are developed. Two modeling strategies, the classes and the pseudodistribution approach, are applied to handle the multidimensional property distributions that result from this reaction mechanism and to get detailed structural property information, e.g., on the chain length distribution and the distribution of TDBs. The structural property information is then used to develop reduced models with significantly lower computational effort, which can be used for process design, on‐line applications or coupled to computational fluid dynamic simulations. To validate the derivations, the models are first compared against each other and finally to experimental results from a continuous stirred tank reactor. The evolution of monomer conversion and molecular weight average data as well as molecular weight distributions can be represented very well by the models that are derived in this article. These results support the correctness of the reaction mechanism predicted by quantum mechanical simulations.

A first intense investigation in the kinetics of radical polymerization of NVP was done by Senogles et. al. [7] They revealed a variation of the activation energy for the propagation step Radical PolymerizationAn improved kinetic model for the radical polymerization of N-vinyl-pyrrolidone (NVP) in aqueous medium is developed. Quantum chemical simulations reveal that the transfer to polymer is of minor importance whereas the transfer to monomer by hydrogen abstraction in 3-position of the pyrrolidone ring leads to a radical with a double bond which initiates a new chain bearing a terminal double bond (TDB). The resulting dead chains with one, two, or more TDB are the main source for a strong increase of molar mass in batch reactors at high conversion due to long chain branching and crosslinking. This can be a source for gel formation and fouling in continuous reactors. www.advancedsciencenews.com www.mre-journal.de

The European project F 3 Factory aims at designing small to medium scale plants consisting of standardized container assemblies for delocalized production of various chemicals. Within the framework of the F 3 Factory project, the design of a modular, multiproduct, and continuous plant for manufacturing water-soluble polymers is addressed. Free radical polymerization in aqueous solution is examined through two industrial cases: polymerization of acrylic acid (AA) in the presence of chain transfer agent (CTA) and copolymerization of AA with one comonomer. A methodology for performing the transition from batch recipes to continuous operations is proposed. Offl ine and inline monitoring of monomer consumption is achieved using Raman spectroscopy combined with chemometrics. A modular pilot plant meeting the requirements of F 3 Factory project is designed and demonstrated at INVITE (Bayer, Leverkusen). The two polymerization processes are successively operated in the same pilot plant separated by an intermediate extensive washing. For each process, several polymer grades are produced by modifi cation of reaction conditions (inlet fl ow of CTA or reactor temperature). Transition dynamics are characterized using inline monitoring. The fl exibility of the modular plant is demonstrated.

Summary: In this article particular attention is paid to processes of mixing fluids with different viscosities relevant for polymerization where the reaction is fast and mixing is the limiting factor. Apart from this, mixing fluids with different viscosities is still one of the challenging tasks in industrial chemistry. Therefore, the characterization of mixing elements is another important topic.Two different multiple chemical reactions, based on the principle of competitive‐parallel reactions, were used and compared to investigate (micro)mixing efficiency in polymerization reactors. The well‐known Villermaux‐Dushman reaction and the third Bourne reaction were applied. The observed product distribution represents the quantity of segregation of the fluid which gives in turn information about the dependency on certain parameters like type and speed of stirrer, dosing period, feed position, and the viscosity of the fluid.The results from semibatch and continuous stirred tank reactors and two different stirrers, Rushton and INTERMIG® impeller, are discussed.

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