ABSTRACT
The effect of various reactor types on the branched structure formed via chain transfer to polymer during free-radical polymerization is investigated by application of a kinetic model in which the distribution of branching points as well as the average branching density can be calculated. It was found that the residence time distribution and the degree of mixing have a significant effect on the branched structure, and that the branching density distribution is completely different depending on the reactor types used even when the average branching density is the same. In a batch reactor, polymer chains formed in the earlier stages of the polymerization possess larger branching densities than those formed in the later stages of the polymerization at any conversion level, and this tendency is much larger in emulsion polymerization. Polymer produced in a continuous stirred tank reactor (CSTR) possesses a broader branching density distribution with a higher average branching density than for a batch polymerization due to a broad residence time distribution. The present kinetic model that considers the history of each primary polymer molecule is quite general, and can be used to investigate various complex polymerization systems that involve branching and crosslinking regardless of the reactor types used.
