Direct interchange reaction in a homopolymer melt. Evolution of the MWD: an analytical solution

Kinetics of a direct interchange reaction in a homopolymer melt is studied theoretically. Relaxation of the molecular weight distribution to its most probable (Flory) stationary form([1]) is considered. To this end, the time- dependent generating function of the transient distribution is calculated a nalytically. Peculiarities of the relaxation process are investigated for t wo kinds of the initial distribution, namely, the sum of two Flory distribu tions with different number averages (N) over bar (1) and (N) over bar (2), and the delta- function. The former case describes a blend of two polydisp erse polymers whereas the latter corresponds to a monodisperse melt. In eac h case, the dependencies of the differential molecular weight distribution and the weight- and z-average polymerization degrees on the number of inter changes per number average chain are obtained in the explicit form. Earlier studies of this problem are briefly discussed.