MEASUREMENT OF POLYDISPERSITY OF ULTRA-NARROW POLYMER FRACTIONS BY THERMAL FIELD-FLOW FRACTIONATION

In this paper the authors demonstrate that the polydispersity mu equals M OVER BAR //w/M OVER BAR //N of narrow polymer fractions can be readily obtained by measuring band broadening and its velocity dependence in a thermal field-flow fractionation (thermal FFF) system. The polydispersities of a series of four narrow polystyrene samples prepared by anionic polymerization were consequently determined by thermal FFF and found to be much smaller (1. 003-1. 006) than the ceiling values (1. 06) suggested by the suppliers. As part of this investigation, an experimental study of band dispersion in thermal FFF is used to examine current theory.