z-average molar mass

{
  "id": "MLC-T-CHM-012791",
  "term": "z-average molar mass",
  "field": "Chemistry",
  "definition": "An average molar mass in which each chain is weighted by w times M squared, computed as the sum of w M^2 divided by the sum of w M, where w is the weight fraction. It stresses the heaviest chains more strongly than the weight-average does, so it exceeds Mw for any polydisperse sample. Sedimentation equilibrium in an ultracentrifuge and size-exclusion chromatography are common ways to obtain it.",
  "subject": "Polymer",
  "see_also": [
    "molar-mass average"
  ],
  "references": [
    "PAC, 2015, 87, 71. 'Definitions of terms relating to individual macromolecules, macromolecular assemblies, polymer solutions, and amorphous bulk polymers (IUPAC Recommendations 2014)' on page 83 (https://doi.org/10.1515/pac-2013-0201)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/z-average-molar-mass/"
}