Abstract
The coupling of a low-pressure size exclusion chromatography (SEC) with a modified Ubbelohde capillary viscometer is described. This SEC/viscometry system measures the flow time of aliquot fractions (5ml) of the SEC effluent along with the refractive index change. This dual detection leads to the determination of the intrinsic viscosity as a function of the elution volume, thus allowing a precise use of Benoit's universal calibration. Moreover information of the branching factors (degree of long-chain branching, long-chain branching frequency) can be calculated under certain assumptions. As an example the changes in molar-mass distribution and branching factors during mechanical shear degradation (mastication) of special polychloroprene samples were investigated. It is shown that the SEC/viscometry system is especially suitable for the characterization of polymers with broad molar-mass distribution and extremely high molecular tails. The data provided by this method are useful for the investigation of the viscoelastic behaviour of concentated polychloroprene solutions and for quality control of polymers in the rubber and adhesives industries.
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