It can be stated that the effect of carbon black in a rubber vulcanizate with regard to dynamic properties can be explained by assuming physical adsorption of rubber on the black surface. The effect can be represented by assuming an adsorbed layer having different properties from the bulk rubber taking the layer thickness to be at least 20 A. Adsorption-desorption from this layer causes non-linearity and may contribute to losses observed in the glass transition. This adsorption is analogous to adsorption of simple liquids in microporous systems such as silica gel and activated carbon.