Magnetic levitation of plastic chips: Applications for magnetic susceptibility measurement and magnetic separation

Magnetic levitation of polyethylene, polycarbonate, polypropylene, polystyrene, poly(methyl methacrylate) and polyamide was carried out using a compact superconducting magnet (vertical bore, 1500T(2) m(-1)). First, their diamagnetic susceptibilities were calculated from the product of the magnetic field and the field gradient necessary for levitation. Second, polypropylene, polyamide, and poly(ethylene terephthalate) chips were separated by magnetic levitation. Magnetic levitation is shown to be a convenient and useful technique for both diamagnetic susceptibility measurements and magnetic separations of diamagnetic substances.