Polycondensation reaction simulation

Simulation experiments of a different type were carried out by two Japanese researchers (Matsunu, 2000 Imai et al., 1999a, b). They used a simulation reactor to study processes which may occur at hydrothermal vents (see Sect. 7.2). In this case, the activation energy for the polycondensation reaction of amino acids has its origin in the Earth s interior. In the high pressure hot water reactor used, the reaction... 

Application of combinatorial algorithms to random stepwise polymerization provides a buis for the understanding of the effect of ring formation on network structures and sol con sitions. A substantial portion of the sol is cyclic. Comparison with experimental data, such as ring fraction measurements ( ) or sol fraction analysis by GPC or HPLC, could be useful to verify the findings obtained in these computer simulation. The progreun can be e lsily adapted to other polycondensation reactions, and to cover the entire range of the polymerization process. 

As discussed earlier, solid-state polymerization reactions are used to increase the degree of polymerization in the production of nylon-6 and nylon-6,6. The solid-state polymerization process has been studied by process simulation. Mallon and Ray [208] developed a comprehensive model to handle the reactions in polymers undergoing polycondensation reactions in the solid state. The polymer crystalline fraction is modeled as containing only repeat units,... 

In this section, the kinetics of the second step, that is, the polycondensation reaction of aliphatic polyesters, is investigated and a simple theoretical model is proposed to simulate both esterification and transesterification reactions taking place during polycondensation. 

For calculation of the equilibrium compositions of the liquid phase either the equilibrium constants of the dissociation and polycondensation reactions have to be known or they can be computed by methods which use the approach of minimizing Gibbs free energy [200-202]. In addition, ab initio modeling techniques such as density functional theory (DFT) in combination with reactive molecular dynamic (MD) simulations could be used. Once the liquid phase system is modeled, there are in principle two options to describe the vapor-liquid equilibrium. Either equations of state (EOS) or excess Gibbs free energy models (g -models) may be used to describe the thermodynamics of the liquid... 

In conclusion, the goal of predictive process modelling has not yet been achieved due to the interference of chemical reactions with mass transport. All polycondensation models and process simulators available in the public domain, such as Polymer Plus from AspenTech or Predici from CIT, as well as in-house polycondensation models from engineering companies and producers, cannot be used for design or scale-up successfully without the use of fitting parameters. 

Use of Continuous System Modeling Program (CSMP) to Simulate Polymerization, Polycondensation, and Polymer Modification Reactions... 

The numerical results obtained via an MD/percolation simulation are also shown to be in excellent agreement with those obtained via the corresponding gelation simulation of the random polycondensation of tetrafunctional units with intramolecular reaction allowed [10]. 

For Euclidean object Dj.= d and pfr = const = pEnc. For fractal object increasing (or MM and N) in polycondensation process at a=const results to pfr reduction in virtne of the condition Dj,< d [52]. Therefore there are critical values MMc(Nc) and tc, above which synthesis reaction ceases [118, 119, 121]. This process is simulated within the frameworks of irreversible aggregation models according to the mechanism cluster-cluster. 

The main conclusion of the present paper is that, what reaction cessation in polycondensation process is limited by purely physical factor, namely, the achievement of macromolecular coil density of solution density in which reaction proceeds. The possibility of such treatment is due fully to macromolecular coil fractality. The indicated processes are simulated within the framework of an irreversible aggregation models over mechanism cluster-cluster. The critical values of molecular weight and reaction duration, above which a S5mthesis reaction ceases, exist. 

Esterification and polycondensation kinetics of PPSu synthesis can be well described on the basis of rather simple simulation models, taking into account the reaction kinetics and the functional group modeling approach. The latter is a very beneficial technique which includes aspects of the reaction mechanism although with the minimum computational effort. 

Monomeric herbicides of diethanolamine derivatives were also prepared, followed by melt polycondensations with dicarboxylic acids to give the corresponding herbicide polyesters (Scheme 3.14) [139]. Solution polycondensation was used in the synthesis of the herbicide-polyurethane derivatives by the reaction of diethanolamine derivatives with HMDI. The linear polymers were crosslinked by reaction with HMDI (5, 10 %) to afford swellable polymeric materials. The preformed amine-containing polyester was also modified with 2,4-D. The hydrolysis rate of 2,4-D from the polymers was measured under different simulated conditions. 

Prediction of the whole CLD should be possible only with Monte Carlo methods, with their usual drawbacks [36]. Nevertheless, polycondensations are easier to simulate by Monte Carlo than other polymerizations, since all reactions have more or less the same time scale. 

Gupta et al. simulated polymerization of caprolactam including all important reactions reversible ROP, polycondensation, polyaddition, and cyclization reactions as well as the reaction with monoftinctional acids and found that reactions constituting the ring-chain equilibria influence the molar mass distribution of product. 

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