Synthesis and properties of magnets/polyethylene composites

Polyethylene-based magnetic composites have been prepared by ethylene polym erization on the surface of NdFeB magnets, which is previously activated by ball milling with catalyst components. The level of magnets has been contr olled by catalyst preparation and polymerization parameters such as Al/Ti r atio and polymerization temperature. The coertivity and the residual magnet izability were investigated. It was found that the magnetic properties of m agnet powders are largely retained. In addition, in contrast to composites prepared by melt mixing, the adhesion force between magnets and polymer mat rix is improved significantly and better mechanical properties are expected . (C) 1999 John Wiley & Sons, Inc.