This article is intended to establish a comprehensive interpretation of the noticeable differences in the dynamic mechanical behaviors of polypropylene/talc composites with and without modified interphases. The latter are discussed on the basis of different Surface treatments applied to the reinforcement particles. To this end, a series of 75/25 (w/w) polypropylene/talc composites with and without interfacial modifications from the reinforcement side were evaluated by dynamic mechanical analysis. The proven capability of this technique analysis to follow the transitions and structural and morphological changes in organic polymers, which are largely influenced by the degree of compatibility between the components of heterogeneous materials based on polymers, was used in this study to check and discuss the kinds and efficiencies of different physisorption- and chemisorption-based processes carried out on the surface of talc particles. We tackled this study by embracing the different relaxation phenomena taking place in the polymer matrix. To this end, five different temperature intervals were distinguished according to the relaxation phenomena taking place. Finally, a correlation between the parameters on the microscopic scale and others on the macroscopic scale appeared to emerge. Thus, the interfacial effects caused by the modified reinforcements could be determined by observations on either scale. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 551-561, 2009