The Computer Simulation Based On The PMMA

Poly(methyl methacrylate)(PMMA) is a major commodity plastic and widely used due to its excellent transparent.In the production of the casting organic glass,the polymerization is easy to be out of control since the reaction heat is great while the heat transfer is difficult.The product is not always fit for the material.So in this paper,we have built the Mathematical Models:the prepolymerization models for MMA bulk polymerization,the sheet model with both Polymerization kinetics and heat transfer and the Optimization model of polymerization.First,the prepolymerization models for MMA bulk polymerization were presented firstly on the basis of the elementary reactions and species mass balance,and considering the influences of cage,gel and glass effects on the rate constants and physical properties.The proposed models are applicable for polymerization system initiated by individual and composite initiator.After proved the model is stiffequations,it was solved by using implicit backward differentiation formulas.The effects of time,temperatures,type and concentration of initiators on the conversion and molecular weight in the polymerization process were simulated by the models,and compared with experimental data,with good fitness.Second,with the conclusions above,the sheet model with both Polymerization kinetics and heat transfer was built.Polymerization kinetics and heat transfer were coupled in the one dimensional casting sheet model,the factors affecting both were investigated from a holistic view in the thesis.Because the heat transfer model is a Partial differential equation of one-dimension,it was solved by using the classical difference scheme.Polymerization kinetics and heat transfer are coupled in the one dimensional casting sheet model.The effects of the time,temperature,heating process,type and concentration of initiators and thickness of the sheet on kinetics and heat transfer in the polymerization process were simulated by the casting models.The prepolymerization model and one dimensional casting sheet model are helpful to understand the dynamic behavior and heat transfer behavior during MMA bulk polymerization and to instruct the production of the casting organic glass.Based on the results and conclusions above,the Optimization model of polymerization was built in the thesis.The model can solve not only the polymerization problems with the constant temperature but also the ones with the temperature changed.And the Optimization model was solved by genetic algorithm.The genetic algorithm in this paper was improved to deal with the special problem,so the algorithm is more fixable,convenient.The convergence of genetic algorithms was analysis in the thesis.The effects of the time,temperature were simulated by the optimization modes.The result got by the model is agreed with the theories of the PMMA that we have known.