The pressure−volume−temperature (PVT) dependence of commercial poly-e-caprolactam melt (PA-6) and based on it a nanocomposite containing 1.6 wt % of exfoliated montmorillonite (PNC) as well as their 1:1 mixture was determined at T = 300−560 K and P = 0−150 MPa. Incorporation of clay into PA-6 resulted in lowering the specific volume of PNC by about 1.0%. For all three molten resins excellent agreement between experiment and the results from Simha−Somcynsky lattice−hole theory was found. The hole (free volume) fraction, a sensitive indicator of structural changes, shows a pressure-dependent reduction of ca. 14−15% in PNC as compared with the neat PA-6. An evaluation of the binary interactions from the computed mean scaling parameters of the theory requires definition of the constituents. On the basis of experimental and computer simulation results in the literature, the following model was adopted: Flat disk particles of specified diameter are covered with a uniform layer of solidified PA-6 of specified t...