The principle of a Davenport density column is simple and accurate: two different organic “solvents” with different densities are mixed in such a way that a density profile over the height of the column is obtained. By applying floaters with a predefined density to the column a calibration curve can be prepared. Polymeric samples with unknown densities can now be measured. The use of the right “solvents” is essential for a good measurement. The polymeric sample shouldn’t dissolve or swell in the “solvents”. So, non-solvents for the specific polymeric samples are needed. Next to that a combination of “solvents” should be found with different densities and good miscibility in a specific density range.
The preparation of a Davenport density column is laborious and time consuming. Thereafter the column can be used for several weeks to months depending on the intensity of use. After a certain time period the gradient is disturbed and a new column has to be prepared.
: PET, Polyamide, Polyacrylonitrile, Aramid, PEF, PLA, Carbon fiber, Cellulose