Premium
Determination of compositional heterogeneity in butadiene–styrene copolymers by density gradient ultracentrifugation
Author(s) -
Stacy C. J.
Publication year - 1977
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1977.070210820
Subject(s) - cyclohexane , branching (polymer chemistry) , copolymer , density gradient , styrene butadiene , styrene , polystyrene , velocity gradient , polymer chemistry , intermolecular force , materials science , ultracentrifuge , chemistry , thermodynamics , polymer , organic chemistry , molecule , chromatography , physics , quantum mechanics
Sedimentation equilibrium in a density gradient gives a sensitive intermolecular composition analysis of styrene–butadiene copolymers. This information is sometimes unobtainable by other analytical techniques. The density gradient is formed by action of the centrifugal field upon a carbon tetrachloride–cyclohexane mixture, and the equilibrium position of each polymeric solute in the gradient depends upon its effective buoyant density. The large difference in styrene and butadiene densities makes possible accurate composition calibrations which are independent of molecular weight and branching.