Long chain branching in emulsion polymerization

A kinetic model for evaluating the degree of polymerization of a branched polymer produced in emulsion is developed. Only chain branching occurring through chain transfer to polymer has been considered. The model accounts for chain compartmentalization and, when coupled to a model able to describe the evolution of the polymerization system, allows to evaluate the cumulative properties of the produced polymer both in the pre- and post-gel phases. The difficulties related to the description of a heterogeneous polymer chain population and of gel formation are overcome by using the ''numerical fractionation'' technique. A parametric analysis of both instantaneous and cumulative properties is reported and discussed, with special attention to the role of radical compartmentalization in determining the molecular weight properties of an emulsion produced polymer. (C) 1997 John Wiley & Sons, Inc