Modulated temperature differential scanning calorimetry is used to explore the interactions between a poly(amide) 6 matrix and various types of clay reinforcement. During quasi-isothermal crystallization of the polymer/clay nanocomposites, an excess contribution is observed in the recorded heat capacity signal, due to reversible melting and crystallization. It is proposed that the magnitude of this excess contribution can be used to qualify the polymer/clay interfacial interaction, as it is directly linked to the segmental mobility of the polymer chains in the interphase region, where both the crystalline and amorphous polymer fractions are affected. It is shown that the interfacial interaction strongly depends on the type of clay filler used. These interactions play a key role in the development of specific material properties for the different types of nanocomposites. A simple interphase model for the poly(amide) 6/clay nanocomposites is proposed. (c) 2005 Elsevier Ltd. All rights reserved.