Optimal Temperature for the Control of the Product Molecular Weight Distribution in Batch Polymerization: Simulation and Experimental Results

A method to determine an optimal temperature profile that guarantees products having controlled molecular weight distribution (MWD) and desired values of molecular weight (M(w)) is presented. The base case is the batch polymerization of MethylMethAcrylate, initiated by AIBN. On the basis of the kinetic model, the optimal temperature profile is determined by imposing that the value of the instantaneous chain length is maintained constant, thus counteracting the effects of the increase of viscosity, which leads to broad MWD. Some approximations permit to express, in a straightforward way, the relationship between the optimal temperature and the conversion as a function of the initial conditions. The validity of the simplifying hypotheses that have been assumed is confirmed first by simulation results and then by a comparison with experimental runs conducted in a lab-scale unit, with determination of MWD made by means of GPC. The obtained results suggest that it is possible to decouple the problem: acting on the operating temperature to control the MWD, acting on initial temperature, and initiator concentration to influence the M(w). The possibility of application to industrial reactors has also been investigated,taking into account their peculiarities and constraint