The lognormal and gamma distribution models for estimating molecular weight distributions of polymers using PGSE NMR

Nathan H. Williamson*, Magnus Nydén, Magnus Röding

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)

Abstract

We present comprehensive derivations for the statistical models and methods for the use of pulsed gradient spin echo (PGSE) NMR to characterize the molecular weight distribution of polymers via the well-known scaling law relating diffusion coefficients and molecular weights. We cover the lognormal and gamma distribution models and linear combinations of these distributions. Although the focus is on methodology, we illustrate the use experimentally with three polystyrene samples, comparing the NMR results to gel permeation chromatography (GPC) measurements, test the accuracy and noise-sensitivity on simulated data, and provide code for implementation.

Original languageEnglish
Pages (from-to)54-62
Number of pages9
JournalJournal of Magnetic Resonance
Volume267
DOIs
Publication statusPublished - Jun 2016
Externally publishedYes

Keywords

  • Pulsed gradient spin echo NMR
  • Molecular weight distribution
  • Self-diffusion
  • Scaling law
  • Lognormal distribution
  • Gamma distribution
  • Polydispersity

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