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The behavior of internal friction Q-1 and dynamic shear modulus has been studied inpolypropylene charged with either different volume fraction or size of magnetite (Fe3O4) particles,as a function of the applied magnetic field at 318 K. An increase of the alternating (AC) magneticfield oscillating with 50 Hz, leads to an increase of the internal friction. In addition, during thesubsequently decreasing alternating magnetic field, the internal friction decreases, but a hystereticbehavior appeared. In fact, the internal friction of the decreasing part of magnetic field amplitude isfound to be smaller than during the previously increasing amplitude part of the treatment with thealternating magnetic field. Subsequent magnetic treatment cycles, lead to successively decreasinginternal friction. In contrast, during the increase of a direct (DC) magnetic field, the internal frictiondecreases and the elastic modulus increases. The behavior of the internal friction and the elasticmodulus during the application of an oscillating magnetic field (AC) is discussed on the basis of thedevelopment of both, a new zone with different rheological characteristics than the matrix but of thesame material (self inclusion), and/or a deteriorated or damaged zone (chain?s cuts) of the polymermatrix in the neighborhood of the magnetite inclusion. These effects are promoted by the movementor small relative rotation of the magnetite particles related to the surrounding matrix controlled bythe oscillating field. The behavior of the internal friction and elastic modulus during the applicationof a direct (DC) magnetic field is discussed on the basis of the increase of the internal stresses intothe polymer matrix due to the promotion of the magnetomechanical stresses.