Cure and mechanical properties of recycled NdFeB-natural rubber composites

Magnetic polymer composites containing recycled neodymium-iron-boron (NdFeB) powder and natural rubber (NR) were prepared by the two-roll mill technique. Their mechanical and cure properties were studied as a function of NdFeB loading from 0–120 phr. With increasing magnetic loading, the cure time of the NdFeB-NR composites were exponentially decreased because of the reduction of the polymer chain crosslink. The tensile strength of the NR compound, related to the cure characteristics, was reduced by 40% by the addition of 10 phr NdFeB fillers because of the inhibition of the stress-induced crystallization. However, the variation in loading from 30–90 phr has modest effects on the tensile strength as well as elongation at break and the hardness. Furthermore, recycled NdFeB-NR composites had higher modulus and lower percentage of swelling in this magnetic loading regime. Simple tests confirmed the distribution of magnetic stray field around pieces of NdFeB-NR composites.