Density measurement via magnetic levitation: Linear relationship investigation

The density of a polymer suspended in a stable state in a paramagnetic solution can be measured in magnetic levitation according to the levitation height. This method requires a complicated benchmark process prior to measurement, and the linear relationship between the density and the levitation height has not been investigated. This paper investigates the linear relationship in the magnetic levitation method, where COMSOL software was applied to simulate the magnetic field. Devices with separation distances (d) between 32 mm and 50 mm had high linearity (R2 > 0.996). The device where d = 43 mm had the highest linearity (R2 = 0.99875). Several experiments with various devices, standard glass beads and polymers were performed to validate the method. The experiments showed that this method had a high accuracy (<0.004 g/cm3 when d = 43 mm). The convenient measuring process enabled simple and quick density measurement for polymers in various devices with the proposed expressions and parameters. The proposed method has broad application prospects throughout density-based polymer testing.