An estimation of the polydispersity of fractions by means of the mathematical fractionation method

The method of mathematical fractionation was used to estimate the values of the polydispersity index (u = Mw/Mn) of the fractions obtained from a polymer with the Schulz‐Zimm distribution of molecular weights. A general correlation of u values with the fraction size and phase volume ratio was established. A minimum was found in the dependence of the polydispersity index on the fraction size (at about 30–40%). On the basis of these calculations conditions could have been predicted for fractions with u = 1.1 to be obtained in a larger amount (20–30% by weight of the original polymer).