Molecular weight distribution of products of free radical nonisothermal polymerization with gel effect. Simulation for polymerization of poly(methyl methacrylate)

A gel effect model for the free radical polymerization of PMMA under nonisothermal conditions has been used to simulate the profiles of various system parameters, such as temperature, initiator concentration and conversion. Cumulative molecular weight and instantaneous radical molecular weight profiles for processes with greatly different histories have been computed using the method of moments. Continuous approximation of the discrete variable, degree of polymerization, renders the transformation of a large set of ordinary equations for species conservation into partial differential equations. The resulting radical and dead polymer molecular weight distributions give averages consistent with those found by the method of moments. Basic rules of thumb correlating the product molecular weights with the governing process parameters have been established based on simulations applicable to either plug flow or well-stirred batch reactors.