Modeling the melt transesterification of polycarbonate

Abstract

A mathematical model of the melt transesterification of polycarbonate in a mechanically agitated reactor system without a distillation column is proposed. Penetration theory is applied to the mass-transfer operation of volatile components in both a transesterification reactor and a polymerization reactor by simplification of the flow pattern. The applicability of the proposed model is examined by the comparison of its predictions with experimental data of the collected condensate of volatile components, the end-group ratio, and the weight fraction distribution of the resulting polymer. The end-group ratios have been determined by carbon-13 nuclear magnetic resonance spectroscopy, and the distribution of weight fractions has been measured by gel permeation chromatography. It is shown that the model's predictions are very consistent with the experimental data.

Decoupling Study of Melt Polycondensation of Polycarbonate: Experimental and Modeling of Reaction Kinetics and Mass Transfer in Thin Films Polycondensation Process

“…The kinetic constant, thermodynamic equilibrium constant, and mass transfer coefficient of volatile are estimated based on the experimental data reported above, with the help of the builtin function lsqnonlin() (nonlinear least squares method) in MATLAB. The objective function for optimization is based on the phenolic end-groups concentration, as shown in Equation (21). The results of estimated parameters are listed in Table 1.…”

“…Generally, the process of molecular diffusion is related to the diffusivity ( D ) of small molecules in polymer melt . The diffusivity of phenol in polycarbonate melts has been reported by several researchers, however, none of them have reported it experimentally. Herein, the objective of modeling the diffusion kinetics of phenol is to experimentally derive the effective diffusivity ( D ) of phenol in the polycarbonate melt.…”

“…Qin et al developed a model of continuous melt transesterification in a stirred tank reactor by using phase equilibrium assumption and the moment method of molecular weight distribution, while the transesterification stage was investigated only. Hsu and Wong and Hsu et al proposed a mathematical model of the melt transesterification of PC without a distillation column. Kim and Choi and Kim presented a vapor–liquid equilibrium model and a two‐phase mass transfer model for the multistage melt polycondensation of PC in batch and semibatch reactors with the molecular weight of PC less than 10 000 g mol −1 .…”

Synthesis and properties of bisphenol‐Z polycarbonate via melt transesterification

“…Interestingly, Na 2 CO 3 generates a polymer with the highest molecular weight among these catalysts. This is attributed to the weak polarization of the DPC carbonyl group and the low nucleophilicity of the BPZ hydroxyl group, the Na + ion appears to fortify the polarization of the DPC carbonyl group by forming metal‐carbonyl coordination, 26 and the suitable alkaline strength fortify the nucleophilicity of the BPZ hydroxyl group by increasing the degree of BPZ ionization. However, high reaction temperature and strong alkalinity of NaOH can cause the ring‐opening reaction of the cyclohexyl group in BPZ and depolymerization of polymer, resulting in a decrease in molecular weight.…”

Reaction kinetics of melt post‐polycondensation process for polycarbonate in film state

“…The melt viscosity increases sharply with the improvement in molecular weight, as a result, the apparent reaction rate gradually shifts from reaction control to mass transfer control 16 . To drive the reaction forward to produce high molecular weight PC, the main reaction byproduct phenol must be removed effectively from the high viscosity polymer mixture by applying low pressure 17 or using an inert purge gas 18 . In addition, a novel synthetic process for preparing PC between BPA and DPC in supercritical carbon dioxide (SC‐CO 2 ) was developed 19 .…”