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The first part of this article discusses different partitioning options used in modeling emulsion copolymerization of acrylonitrile and butadiene for the production of acrylonitrile‐butadiene rubber (NBR) in batch and continuous reactors. It is observed that the performance of the model using different partitioning methods for estimation of monomer concentration in the different phases (i.e., droplet, aqueous and particle) would be very similar by proper selection of the different parameters of the particular partitioning method. In the second part, the effects of important aspects (during the continuous production of NBR) such as desorption and monomer soluble impurities on polymer properties are discussed. The third part of the paper focuses on procedures and benefits of different kinds of reactor start‐ups, such as starting the reactor(s) full of water, half full of water, full of “batch recipe” or empty. All of the above studies and analysis are targeted towards their effect on principal emulsion polymer characteristics such as number‐ and weight‐average molecular weights, monomer conversion, copolymer composition (bound acrylonitrile), tri‐ and tetra‐functional branching frequencies, and number and average size of the polymer particles. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

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This article focuses on important aspects related to the production of acrylonitrile‐butadiene rubber (nitrile rubber or NBR) emulsions using a train of eight continuously stirred tank reactors. The first aspect we discuss concerns miscellaneous operating procedures, targeted toward achieving desired properties of the NBR emulsion and at the same time reducing the amount of off‐spec material during the transient period. In one of the operating procedures discussed, the first reactor is started full of “batch recipe,” whereas the remaining reactors in the train are half full with all reaction ingredients. In another case, we discuss an alternative design scenario, where the first reactor in the train is of a much smaller volume compared with the following reactors. The benefits of these two operating (production) scenarios are illustrated by comparison of different polymer and latex properties obtained with the commonly used procedures. Second, we discuss a novel criterion that can quantitatively distinguish between Cases I and II kinetics emulsion polymerization behavior with respect to continuous reactor stability (oscillatory behavior). Finally, additional feed policies are addressed, such as splitting the more reactive monomer and/or other reaction ingredients among the reactors of the train for better control of certain desired properties. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers