Density – Gradient Column Method
One of the most accurate methods to determine the density of plastics and rubbers in kg/m3 is the gradient column method (ISO 1183-2). The principle of the process is that two miscible liquids can be mixed at a controlled mixing rate and temperature into a tube so that a uniform density gradient is formed from the top to the bottom of the tube. Calibrated floats with known density are then immersed into the tube for reference. After a fixed period of time, the position of the samples in the column is measured against a graduated scale and compared against the data for the calibrated beads
The sample densities are derived by calculation.
