| Résumé | The pressure-volume-temperature (PVT) dependencies of commercial polypropylene melt (PP) and its nanocomposites containing X wt % of organoclay (Cloisite-15A, or C15) and 2X wt % of a compatibilizer were determined at T ) 450-530 K and P ) 0.1-190 MPa. C15 was used at concentrations: X ) 0, 2, and 4 wt %. Three functionalized PP’s were used as compatibilizers: two maleated and one grafted with glycidyl methacrylate. Incorporation of X ) 2 wt % C15 into PP resulted in reduction of specific volume by ΔV ≈ 1%, but that of free volume (hole) fraction by Δh ≈ 5%. The latter quantity was computed from the Simha-Somcynsky lattice-hole equation of state. Furthermore, at constant T and P the hole fraction was found to be linearly related to the bulk-average energetic interaction parameter and to be a sensitive indicator of structural changes. In binary (polymer + organoclay) systems Δh is linearly related to the interlayer spacing, d₀₀₁. So, where statements from the previous paper are repeated or there are similarities, this is done for purposes of comparison. In three-component systems (with a compatibilizer) the proportionality has been preserved, but large changes of Δh result in relatively small changes of d₀₀₁. Mechanical properties hardly correlate with either Δh or d₀₀₁, as polymer/ compatibilizer morphology and crystallinity complicate the behavior. |
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