Abstract:A Monte Carlo (MC) model is developed to predict molecular weight distribution and branching during the production of arborescent polyisobutylene. The model describes self‐condensing vinyl copolymerization (SCVCP) of isobutylene and inimer via living carbocationic polymerization. Six different propagation rate constants are required to account for two types of vinyl groups and three types of carbocations in the system. MC model predictions are better than predictions from a previous PREDICI material balance mo… Show more
“…As a result, only four apparent rate constants ( k pIMapp , k pMIapp , k pMMapp , and k pSMapp ,) were used in the model. Values of these parameters were estimated using experimental data and are reported in Table . Simulation results agreed well with experimental data corresponding to low average branching levels (about two branches per polymer chain), but were worse for polymers having higher branching levels …”
Section: Introductionsupporting
confidence: 56%
“…Figure shows a simplified reaction mechanism of “one‐pot” living copolymerization of IM and IB developed by Puskas et al The first step is an exchange reaction that converts 4‐(2‐methoxyisopropyl)styrene (MeOIM) to IM. A large excess of TiCl 4 , which is a Lewis acid (LA), is often used in the experiments to ensure that this exchange reaction goes to completion and that there is sufficient LA to initiate the living carbocationic polymerization.…”
Section: Introductionmentioning
confidence: 99%
“…The average branching level for the polymer chains that are produced is: where , is the number average molecular weight for all polymers and is a theoretical molecular weight that would be obtained if IM were consumed as initiator only (i.e., if none of the V I groups could react and only linear PIB was produced).…”
Section: Introductionmentioning
confidence: 99%
“…Several research groups have developed mathematical models for SCVP and SCVCP systems. These models can be classified mainly into two different types: (i) dynamic material balance models and (ii) Monte Carlo (MC) models . These two areas are complementary in that each has advantages that the other does not.…”
Section: Introductionmentioning
confidence: 99%
“…For example, it is relatively straightforward to build individual material balance equations, especially using automated tools like PREDICI but not as easy to formulate and implement models using MC methods. However, MC models can provide very detailed information about the structure of polymer molecules, but dynamic material balance models may not be able to provide such detailed information unless a prohibitive number of differential equations is used …”
An advanced Monte Carlo (MC) model is developed to predict the molecular weight distribution and branching level for arborescent polyisobutylene produced in a batch reactor via carbocationic copolymerization of isobutylene and an inimer. This new MC model uses differential equations and random numbers to determine the detailed structure of dendritic polymer molecules. Results agree with those from a traditional MC model for the same system, but the proposed model requires considerably less computational effort. The proposed MC model is also used to obtain information about polymer segments between branch points and dangling polymer segments.
“…As a result, only four apparent rate constants ( k pIMapp , k pMIapp , k pMMapp , and k pSMapp ,) were used in the model. Values of these parameters were estimated using experimental data and are reported in Table . Simulation results agreed well with experimental data corresponding to low average branching levels (about two branches per polymer chain), but were worse for polymers having higher branching levels …”
Section: Introductionsupporting
confidence: 56%
“…Figure shows a simplified reaction mechanism of “one‐pot” living copolymerization of IM and IB developed by Puskas et al The first step is an exchange reaction that converts 4‐(2‐methoxyisopropyl)styrene (MeOIM) to IM. A large excess of TiCl 4 , which is a Lewis acid (LA), is often used in the experiments to ensure that this exchange reaction goes to completion and that there is sufficient LA to initiate the living carbocationic polymerization.…”
Section: Introductionmentioning
confidence: 99%
“…The average branching level for the polymer chains that are produced is: where , is the number average molecular weight for all polymers and is a theoretical molecular weight that would be obtained if IM were consumed as initiator only (i.e., if none of the V I groups could react and only linear PIB was produced).…”
Section: Introductionmentioning
confidence: 99%
“…Several research groups have developed mathematical models for SCVP and SCVCP systems. These models can be classified mainly into two different types: (i) dynamic material balance models and (ii) Monte Carlo (MC) models . These two areas are complementary in that each has advantages that the other does not.…”
Section: Introductionmentioning
confidence: 99%
“…For example, it is relatively straightforward to build individual material balance equations, especially using automated tools like PREDICI but not as easy to formulate and implement models using MC methods. However, MC models can provide very detailed information about the structure of polymer molecules, but dynamic material balance models may not be able to provide such detailed information unless a prohibitive number of differential equations is used …”
An advanced Monte Carlo (MC) model is developed to predict the molecular weight distribution and branching level for arborescent polyisobutylene produced in a batch reactor via carbocationic copolymerization of isobutylene and an inimer. This new MC model uses differential equations and random numbers to determine the detailed structure of dendritic polymer molecules. Results agree with those from a traditional MC model for the same system, but the proposed model requires considerably less computational effort. The proposed MC model is also used to obtain information about polymer segments between branch points and dangling polymer segments.
A mathematical model is developed for estimating kinetic parameters that influence the production of arborescent polyisobutylene via carbocationic copolymerization of inimer (IM) and isobutylene. Six different propagation rate constants arise due to the two types of vinyl groups and three types of carbocations. These six parameters are estimated using parallel simulation systems in PREDICI that track (1) functional groups, (2) internal and dangling segments in the polymer, and (3) concentrations of IM and polymer molecules. Parameter estimates obtained using the proposed model result in a better fit to literature data than was obtained using a previous model that neglected two types of propagations reactions. Predictions from the proposed model are consistent with Monte Carlo simulations for molecular weight distribution of the internal and dangling segments.
A statistical modeling procedure is established for carbocation polymerization with the characteristics of living with chain transfer. A single state model is suggested for cases of narrow molecular weight distribution, whereas a multi-state model is claimed for cases of broad distribution. In the multi-state case, it is demonstrated how the overall kinetics can be derived using the expectations and variances of the kinetic parameters rather than those of individual states, thereby simplifying the modeling step. Although the expectation and variance do not follow the relationship of the Arrhenius equation, a procedure is given for how to account for temperature dependence. The proposed statistical method minimizes the number of parameters to identify and therefore is expected to help establish a model with fewer experiments. The whole procedure is demonstrated through an experimental study of isobutylene polymerization.
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