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Number Average Molecular Weight




\bar{M}_n= rac{\sum_i N_iM_i}{\sum_i N_i}

The number average molecular weight of a polymer can be determined by Gel Permeation Chromatography , Viscometry , Light Scattering , Analytical Ultracentrifugation , Vapor Pressure Osmometry , End-group titration, and colligative properties.

An alternative measure of the molecular weight of a polymer is the Weight Average Molecular Weight . The ratio of the ''weight average'' to the ''number average'' is called the Polydispersity Index .

''High Number-Average Molecular Weight Polymers'' may be obtained only with a high ''fractional monomer conversion'' in the case of Step-growth Polymerization , as per the Carothers' Equation .