Top topic this week
Back to FAQs
Related FAQs
Frequently Asked Question
Questions asked by users might not always be phrased in the clearest way.
The molecular weights of the polymers are determined using a Gel Permeation Chromatography (gpc) technique. i. Explain how the GPC works? ii. What does the symbols, Mn, mw and mv stands for and write the foumulae
Accepted Answer
## Gel Permeation Chromatography (GPC) Explained:
i. How GPC Works:
GPC separates molecules based on their size. It utilizes a column packed with porous beads. Larger molecules pass through the column faster, as they have less interaction with the beads, while smaller molecules can enter the pores and thus take longer to elute.
ii. Molecular Weight Symbols and Formulae:
Mn: Number-average molecular weight. Represents the average molecular weight calculated based on the number of molecules in the sample.
Formula: Mn = Σ(Ni
Mi) / ΣNi where Ni is the number of molecules with molecular weight Mi.
Mw: Weight-average molecular weight. Reflects the average molecular weight weighted by the mass of each molecule.
Formula: Mw = Σ(Ni
Mi²) / Σ(Ni
Mi) where Ni is the number of molecules with molecular weight Mi.
Mv: Viscosity-average molecular weight. Determined from the viscosity measurements and is sensitive to the shape and size of the molecules.
Formula: Requires specific viscosity measurements and involves the Mark-Houwink equation.
Articles you might like