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NotJohnson
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Homework Statement
I am trying to calculate Mv as part of a lab using GPC data for a polystyrene polymer that I produced with a known polystyrene standard. for the produced PS I have a = .678 and K = .00018 and the standard has a = .725 and K = .011. intrinsic viscosity was measured as .2346
Mn for the polymer from GPC is 23097 g/mol (for reference)
The solvent is THF, I'm not sure if the GPC is conventionally or universally calibrated
Homework Equations
IV (eta) = K*Mv^a (Mark–Houwink-Sakurada equation)
ln (Mv) (of PS produced) = 1/(asa + 1) * ln (Kst/Ksa) + (ast + 1) / (asa + 1) * ln (Mvst)
(sa = produced sample, st = standard) (equation correcting for GPC universal calibration)
The Attempt at a Solution
I used the Mark–Houwink-Sakurada equation and got Mv = 68.08 for the standard
I then used the below equation to solve for my sample and got Mv = 880.62
I am confused as to why this number is so much lower than the Mn or Mw. Is this normal or am I using the wrong procedure or equation to calculate this value?
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