Abstract: The dynamic mechanical properties in terms of the storage modulus E', loss mo-dulus E", and the loss tangentδ of poly (butadiene-co-acrylonitrile) with 40% acrylo-nitrile composites filled with graphite powder and molybdenum disulfide powder fillers have been studied. The effect of the volume fraction of fillers and the polymer-filler interaction on the above meationed parameters and relaxation spectra have been elucida-ted. A model has been tested for calculating the complex modulus E₁ of interphase.