Modeling uses and analysis of production scenarios for acrylonitrile‐butadiene (NBR) emulsions

Abstract

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

Surrogate Models for Online Monitoring and Process Troubleshooting of NBR Emulsion Copolymerization

“…The builtin function, trainlm.m, in MATLAB is based on this algorithm and is used in the simulations for the NBR system. The desired output, Y, is obtained from the mechanistic model, which gives good predictions when compared with the experimental data, as established in previous work [4,5]. The original mechanistic model is highly nonlinear with 32 multiscale state variables.…”

“…This method of obtaining the estimates (for initial reaction ingredients) is easier and less time consuming compared to using the fully mechanistic model. Using the mechanistic model (which is very useful in its own right, as we have shown in previous publications, e.g., Madhuranthakam and Penlidis [4,5]), a trial and error approach has to be used for initial reaction ingredients. During the operation of the reactor train, for any slight discrepancies in the desired properties of the products, it is always possible to fine-tune the estimates obtained using the ANN-based inverse modeling.…”

“…The input variables chosen to be related to any output variable are restricted to the states that have higher impact than others and that can also be used as practical manipulated variables in control applications. For example, when the reactor is started full of batch recipe (for other types of start-up policies refer to [4]), the conversion obtained at the exit of the reactor is expressed as a function of initiator, and acrylonitrile and butadiene (monomers) flow rates, as shown in Equation (2):…”

“…This model is capable of simulating the emulsion polymerisation of NBR in batch and in a train of CSTRs, with add-on options, such as choosing the type of reactor start-up, different modes of monomer partitioning, and the effect of impurities. More detailed information regarding the traits and attributes of this model can be obtained elsewhere [4,5]. The mechanistic model developed by our group is complete and comprehensive and has been used for more than just obtaining the simulated dynamic behavior of commercial trains of CSTRs corresponding to different operating conditions.…”

Stent migration during transcatheter management of coarctation of aorta

“…Both dynamic and SS behaviors depend on how the reactor train is started up and the accompanying operating procedures and feed stream policies. A recent publication from our group [10] has concentrated on different start‐ups of the reactor train and their corresponding effect on the profiles of the different polymer properties. In this article, additional important operating policies and procedures that can be used in the case of a train of CSTRs for the production of NBR emulsions are addressed and discussed.…”