Résumé
Magnetic polymer composite materials have very good rheological (that are characteristic for polymers used as matrix) and magnetic properties superior to those of polymers (due to their magnetic filler) making them useful in many power applications (electromagnetic shielding, permanent magnets etc.). In this paper the results of an experimental study regarding the manufacture and characterization of some composites which have low density polyethylene (LDPE) as matrix and neodymium (Nd) and neodymium-iron-boron (NdFeB) as filler are presented. The manufacture process (with mass content between 0 and 15 %) and their structure (obtained by electronic and optical microscopy) are presented. It is shown that the samples are inhomogeneous and isotropic and the filler particles form clusters of variable dimensions and distances between them.
Then, the first magnetization cycles obtained on neodymium (A) and neodymium-iron-boron (B) samples for three mass concentrations (5, 10 and 15 %) are presented. It is shown for both samples type (A and B) that the hysteresis area cycles increase with filler content being greater for samples B than A. It is shown, also, that the magnetic permeability values increase with filler content, but decrease very quickly with the magnetic field strength.