EXACT WEIGHT FRACTION DISTRIBUTION IN LINEAR CONDENSATION POLYMERIZATION

Since the so-called weight fraction distribution derived by Flory is approximate in the general case, this paper extends the Flory equations to give the true weight fraction distribution over the full range of molecular weight and polymerization parameters for linear condensation polymerization. Equations for true weight fraction are derived from the definition Wx = MxNx/MxNx. Expressions for the x-mer molecules weight Mx are derived as a function of x for case I without and for case II with a product of elimination during the condensation. For case I the so-called weight fraction is equivalent to the true weight fraction only for type i condensation or for type ii when r = 1. For case II it is never equivalent to the true weight fraction. Since the largest error occurs for small x-mers, the true weight fraction distribution is especially necessary for problems with a small average degree of polymerization xn. © 1969, American Chemical Society. All rights reserved.