A comparative study of the properties of different distribution curves

Irene Schnöll-Bitai

Veröffentlichungen: Beitrag in FachzeitschriftArtikelPeer Reviewed

Abstract

The maximum, points of inflection and the derived peak width are enumerated for a Poisson, a Gauss and a Schulz-Flory distribution. Starting with a (not necessarily normalized) number distribution the respective molar mass and hyper distributions are derived and the extrema and the peak width are determined as well. It turned out, that Poisson and (narrow, D <1.1) Gauss distributions can be characterized by the fact that the peak width is an invariant quantity with respect to the number, molar mass and hyper distribution, whereas the peak width changes considerably for a Schulz-Flory distribution. In order to demonstrate the theoretical results commercial polymer standards (prepared by anionic polymerization) were measured by size exclusion chromatography and the constancy of the peak width is demonstrated but the peak widths exceeded by far the theoretically expected values. The influence of axial broadening in size exclusion chromatography is discussed in this context and a simple correction procedure is presented for an ideal Poisson distribution. On the other hand, polymers prepared by stationary radical polymerization displayed a very marked deviation from an invariant peak width, as derived theoretically. It is demonstrated that the location of the peak maximum in the molar mass and the hyper distribution is identical with Mn and Mw, respectively.
OriginalspracheEnglisch
Seiten (von - bis)1754-1762
Seitenumfang9
FachzeitschriftMacromolecular Chemistry and Physics
Jahrgang203
Ausgabenummer12
PublikationsstatusVeröffentlicht - 2002

ÖFOS 2012

  • 104017 Physikalische Chemie

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