MOLECULAR WEIGHT

Polymerization usually produces macromolecules with varying chain lengths. As a result, polymers are described as polydisperse systems.

Commercial polymers have molecular weights greater than 5,000 and contain macromolecules with variable molecular weights. The methods for determining the average molecular weights of polymers include measuring some colligative property, such as viscosity or sedimentation.

Different methods do not correlate well, and determining the average molecular weight requires more than one method. Two methods normally determine the number average and the weight average molecular weights of the polymer.