Four-capillary differential viscometers for high temperature GPC/SEC applications such as the determination of branching in polyolefins
Analysis of the physical properties of polyethylene and polypropylene, used in demanding applications such as medical device manufacture or high performance car mouldings cannot be accurately determined by conventional GPC techniques alone. Several differential viscometer kits are now available from Viscotek to provide the users of all manufacturers high temperature GPC systems with the benefits of multi-detector characterisation of polyolefins.
Using Viscotek's proven, patented four-capillary viscometer design provides excellent sensitivity and extremely reproducible results facilitating more accurate polyolefin analysis than with any other single or multi-capillary configuration.
Providing a direct measurement of intrinsic viscosity and molecular density, which are directly related to polymer size, structure, and branching, Viscotek differential viscometers can be used to identify and quantitate small differences in these parameters.
The unique four-capillary viscometer design means scientists may use the universal calibration principle to determine molecular weight distributions independent of structure and branching.
Advantageously, and unlike conventional calibration methods, the calibration standards in universal calibration methods do not have to have the same chemical structure as the polymer being analysed to give true molecular weights.
By comparison to light scattering that suffers sensitivity problems because of low dn/dc values from polyolefins, viscometric detection facilitates determination of branching and size across the complete molecular weight range.
