Self‐consistency of fractional precipitation method for determining molecular weight distribution in a polymer sample

Abstract

SynopsisMolecular weight distribution curves have been determined for two samples of polystyrene by fractionating them with a conventional single-stage precipitation technique and followed by measurement of the average molecular weights of the fractions by viscometry. The experimental results obtained were analyzed by the usual method of plotting cumulative distribution curves. Subsequently, the distribution curve for a mixture of aliquots of the two samples was obtained and found to agree with the expected curve, which would be the sum of the curves in the two constituent samples. This finding confirms the internal self-consistency of this method for determining molecular weight distribution curves.