Chromatographic investigations of macromolecules in the critical range of liquid chromatography,XIII. Separation of blends of styrene-butadiene rubber and butyl rubber

The separation of blends of styrene-butadiene rubber and butyl rubber is accomplished by liquid chromatography at the critical point of adsorption. Using a non-polar stationary phase and methyl ethyl ketone-cyclohexane as the eluent, the critical point of adsorption of polybutadiene is established. Under these chromatographic conditions, the blends are separated regardless of the molar masses of the components. The exact chemical structure of the blend components can be analysed by coupling the chromatographic separation to FTIR detection. The FTIR spectra of the components reveal information on the styrene and butadiene content and the conformation of the butadiene units (1,2-, 1,4-cis, 1,4-trans units). Poorly soluble high molar mass samples are separated by combining critical separation with a gradient elution technique.