Question

a) Draw an example of a GPC chromatogram obtained for a polydisperse polymer. Label the relative positions of $M_n$ and $M_w$. b) You analyze a sample of polyethylene terephthalate (PET) using a GPC (THF eluent) equipped with multiangle light scattering (MALS) and using a GPC (THF eluent) that calculates molecular weights relative to a polystyrene calibration curve. The $M_n$ value obtained for PET measured using MALS was less than the $M_n$ value measured relative to polystyrene standards. Explain the origin of this discrepancy.

          a) Draw an example of a GPC chromatogram obtained for a polydisperse polymer. Label the relative
positions of $M_n$ and $M_w$.
b) You analyze a sample of polyethylene terephthalate (PET) using a GPC (THF eluent) equipped with
multiangle light scattering (MALS) and using a GPC (THF eluent) that calculates molecular weights
relative to a polystyrene calibration curve. The $M_n$ value obtained for PET measured using MALS was
less than the $M_n$ value measured relative to polystyrene standards.
Explain the origin of this discrepancy.

a) Draw an example of a GPC chromatogram obtained for a polydisperse polymer. Label the relative
positions of Mn and Mw.
b) You analyze a sample of polyethylene terephthalate (PET) using a GPC (THF eluent) equipped with
multiangle light scattering (MALS) and using a GPC (THF eluent) that calculates molecular weights
relative to a polystyrene calibration curve. The Mn value obtained for PET measured using MALS was
less than the Mn value measured relative to polystyrene standards.
Explain the origin of this discrepancy.

Added by Shawn O.

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