Batch polymerization

PVDE is manufactured using radical initiated batch polymerization processes in aqueous emulsion or suspension operating pressures may range from 1 to 20 MPa (10—200 atm) and temperatures from 10 to 130°C. Polymerization method, temperature, pressure, recipe ingredients, the manner in which they are added to the reactor, the reactor design, and post-reactor processing are variables that influence product characteristics and quaUty. 

In a multiprocess train building, an operator was running several batch polymerization reactions. One of these was a copolymerization process involving two monomers, an initiator and an organic solvent. Several of the other processes... 

Batch polymerization is still used. However, most new processes use continuous polymerization and direct spinning. 

Figure 3.20 Typical autoclave cycle for batch polymerization of PA-6,6.5...

Back-biting reactions, 63 Back-end cure, 235 BAK, 28 Bakehte resins, 1 Barrier properties, 26 Batch polymerization, autoclave cycle for, 167... 

During polymerization, when Initiator Is Introduced continuously following a predetermined feed schedule, or when heat removal Is completely controllable so that temperature can be programmed with a predetermined temperature policy, we may regard functions [mo(t ], or T(t), as reaction parameters. A common special case of T(t) Is the Isothernral mode, T = constant. In the present analysis, however, we treat only uncontrolled, batch polymerizations In which [mo(t)] and T(t) are reaction variables, subject to variation In accordance with the conservation laws (balances). Thus, only their Initial (feed) values, Imo] andTo, are true parameters. 

Batch Polymerizations Nine batch polymerizations were performed to verify that our formulation behaviour was unchanged from... 

The styrene conversion versus reaction time results for runs in the laminar flow regime are plotted in Figure 8. Both the rate of polymerization and the styrene conversion increase with increasing flow rate as noted previously (7). The conversion profile for the batch experimental run (B-3) is presented as a dashed line for comparison. It can be seen that the polymerization rates for runs with (Nj e e 2850 are greater than the corresponding batch polymerization with a conversion plateau being reached after about thirty minutes of reaction. This behavior is similar to the results obtained in a closed loop tubular reactor (7J) and is probably due to an excessively rapid consumption of initiator in a... 

Most of the studies reported in the literature are based on batch polymerization systems. For these systems an excellent foundation has been laid for further studies. 

Example 3.6 The isothermal batch polymerization in Example 2.8 converted 80% of the monomer in 2h. You want to do the same thing in... 

The present section analyzes the above concepts in detail. There are many different mathematical methods for analyzing molecular weight distributions. The method of moments is particularly easy when applied to a living pol5mer polymerization. Equation (13.30) shows the propagation reaction, each step of which consumes one monomer molecule. Assume equal reactivity. Then for a batch polymerization. 

Example 13.5 Determine the instantaneous distributions of chain lengths by number and weight before and after termination by combination. Apply the quasi-steady and equal reactivity assumptions to a batch polymerization with free-radical kinetics and chemical initiation. 

Example 13.7 A 50/50 (molar) mixture of st5Tene and acrylonitrile is batch polymerized by free-radical kinetics until 80% molar conversion of the monomers is achieved. Determine the copolymer composition distribution. 

FIGURE 13.6 Copolymer composition distribution resulting from the batch polymerization of styrene and acrylonitrile. 

The main problem with a living polymer is maintaining the strict cleanliness that is demanded by the chemistry. This is a particularly severe problem for large-scale, batch polymerizations, but it is a problem more of economics than... 

The industrial process for which this methodology was developed comprised polymerizing a monomer in the presence of a mixed solvent, the catalyst and other Ingredients. Once the batch polymerization is complete, the product requires removal of the solvents to a specified level. The solvents, an aromatic Cy and aliphatic Cy compounds, are removed by a two-step process schematically shown in Figure 1. As shown, the polymer slurry is initially flashed to a lower pressure (Pj ) in the presence of steam and water. The freely available solvent in the polymer-solvent mixture is removed by the shift in thermodynamic equilibrium. Solvent attached to the surface of the polymer particle is removed by the steam. In this first step, 90% of the total solvents are recovered. The remaining solvents are recovered in the second flash, where the effluent is almost all water with very low concentrations of the solvents. 

MODEL TO PREDICT RESIDUAL MONOMER FOR AN ISOTHERMAL SEMI-BATCH POLYMERIZATION AND AN ISOTHERMAL BATCH FINISHING STEP. 

Optimization of a Batch Polymerization Reactor at the Final Stage of Conversion... 

The various kinetic and thermodynamic factors involved in vinyl free radical polymerization have been considered for the case of a batch (or semi-batch) polymerization being carried out to very high conversion. In particular, computations have been done for the final stage of the reaction when monomer concentration is reduced from approximately 5 volume % to 0.5 volume %. 

In batch or semi-batch polymerization processes it is often desirable to add a "chaser catalyst" towards the end of the reaction to reduce the residual monomer concentration to acceptable levels. The ability of the catalyst to reduce the monomer concentraion to low levels (ca 0.10 vol%) is of considerable importance for economic, envirorunental and physiological reasons. The chaser catalyst addition reduces processing time and increases throughput (Kamath and Sargent (1987)). 

In this paper we present a meaningful analysis of the operation of a batch polymerization reactor in its final stages (i.e. high conversion levels) where MWD broadening is relatively unimportant. The ultimate objective is to minimize the residual monomer concentration as fast as possible, using the time-optimal problem formulation. Isothermal as well as nonisothermal policies are derived based on a mathematical model that also takes depropagation into account. The effect of initiator concentration, initiator half-life and activation energy on optimum temperature and time is studied. 

O DRISCOLL ETAL. Optimkotion of a Batch Polymerization Reactor... 

Computer-Based Laboratory for Developing Practical Automated Feedback Control Systems for Batch Polymerizations... 

The primary goal of the work described here is to provide a means whereby specifiers can become implementers that is, to provide automation systems tools (for the specific case of batch polymerizations) allowing process and production experts to design, implement, maintain, and enhance their own "state-of- the-art" control systems. 

While our specific example is based upon control of batch polymerizations, the procedure we outline could, we feel, be applied equally well to selecting automation tools for many other kinds of processes, particularly those not truly well understood at the outset. 

One final note While the techniques used here were applied to control temperature In large, semi-batch polymerization reactors, they are by no means limited to such processes. The Ideas employed here --designing pilot plant control trials to be scalable, calculating transfer functions by time series analysis, and determining the stochastic control algorithm appropriate to the process -- can be applied In a variety of chemical and polymerization process applications. 

Automated feedback control systems for batch polymerizations advantages, 475... 

In summary, these exploratory data suggest that the chromatographic method used could be a valuable tool for study of this polymerization reaction. Reasonable data were obtained for amount and composition of the copolymer. Formation of graft polymer and/or nitrile rich polymer was detected. More detailed chromatographic study of this batch polymerization could lead to a practical on-line monitoring method... 

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