Effect of coupling agent and filler particle size on melt rheology of polymer‐bonded Nd‐Fe‐B magnets

Abstract The effect of coupling agents and filler particle size on melt rheology of poly(phenylene sulfide)‐bonded neodymium‐iron‐boron (Nd‐Fe‐B) alloy magnets was studied with oscillatory flow experiments to accelerate efforts to optimize their processing. The minimum viscosity of the polymer‐bonded magnets near 290°C was obtained with NdFeB fillers (106–150 particle size range) that were coupled with a silane coupling agent. All the samples tested followed power‐law fluid flow behavior. Morphological and dynamic mechanical analysis of the samples showed that the beneficial function of the coupling agent may be ascribed to enhanced wetting of the magnetic NdFeB powders by the polymer, improving the processability of the polymer bonded magnets.