PARAMETRIC SENSITIVITY OF FREE RADICAL POLYMERIZATION ASSOCIATED WITH GEL AND GLASS EFFECTS

Abstract

The parametric sensitivity is studied of an isothermal homopolymerization system exhibiting the gel and glass effects. As example, the initiated radical polymerization of methyl methacrylate to be achieved in a batch bulk process is considered. For the diffusion controlled reactions, a simple model was proposed containing the dependencies of termination and propagation rate constants with monomer conversion, initiator concentration and temperature. The easiness of handling it and the good agreement between simulation and experimental results are the main features of these models, recommending them for complex engineering studies. The sensitivities of the state variables (initiator concentration, monomer conversion and distribution moments of the chain length) and the model outputs (numerical and gravimetrical average polymerization degrees) with respect to various parameters are computed. It is found that the temperature has the strongest influence in the polymerization process, so it is necessary the stabilization of this parameter with a control loop. The analysis shows that the propagation and initiation activation energies are two of the most important parameters governing the system performance. Almost all the system parameters have the greatest influence at the gel effect moment. Using a calculus based on sensitivity functions, the quantitative estimation of the parameter influence on the system state and output variables are made.