The kinetics of L-lactide ring-opening polymerization initiated by stannous octoate and triphenylphosphine was investigated in a batch apparatus (Haake Rheocord Mixer). Based on the experimental data, a kinetic model is developed, considering a coordination-insertion mechanism. Reactive extrusion experiments were further conducted for the same polymerization process, on a co-rotating twin screw extruder. The melted material flow and mixing was described by using the Ludovic® commercial simulator. Based on the developed kinetic model and simulated flow of L-lactide polymerization mixture, a mathematical model of reactive extrusion process is formulated, describing the evolutions of monomer conversion and average molecular weight along the extruder. The model is predicting with a reasonable good accuracy the experimental data. 相似文献
The free radical grafting of polyethylene with vinyl monomers by reactive extrusion was studied numerically. Numerical computation expressions of key variables, such as the concentrations of the initiator and polymer, grafting degree, average molecular weight and apparent viscosity, were deduced. The evolutions of the above variables were predicted by means of an uncoupled semi‐implicit iterative algorithm. The monomer conversion monotonically increases with decreasing throughput or increasing initial initiator concentration; with increasing barrel temperature, the monomer conversion first increases then decreases. The simulated results are nearly in good agreement with the experimental results.
Summary: Unsaturated polyester is traditionally produced in a batch wise operating reaction vessel connected to a distillation unit. An attractive alternative for the synthesis of unsaturated polyester is a reactive distillation. To value such alternative synthesis route reliable process models need to be developed. In this paper, the strategy is described for the development of the reactive distillation model. Essential parts of the reactive distillation model are kinetic and thermodynamic which are subsequently validated with the experimental data of the traditional batch process such as acid value of the polyester, weight of the distillate and glycol concentration in the distillate. We find that the models predict these important variables reliably. Unsaturated polyester production time is around 12 hours in the traditional batch process. However, the simulation study of the reactive distillation process shows that the total production time of unsaturated polyester in a continuous reactive distillation system is between 1.5 hours to 2 hours for the same product quality as during batch production. The equilibrium conversion is raised by 7% compared to the traditional batch process. The model demonstrated that reactive distillation has the potential to intensify the process by factor of 6 to 8 in comparison to the batch reactor. 相似文献
The gel effect in the reactive extrusion process for free radical polymerization in a closely intermeshing co‐rotating twin screw extruder was investigated. First the reaction kinetic model was constructed mainly on the basis of entanglement theory. Next, numerical calculation expressions for the initiator and monomer concentrations, monomer conversion, average molecular weight and apparent viscosity were deduced. Finally, the evolution of the above variables were shown and discussed for the example of butyl methacrylate. The simulated results of the monomer conversion are in good agreement with experimental results.
