Pressure−Volume−Temperature Dependence of Polypropylene/Organoclay Nanocomposites

Abstract

Received August 24, 2004; Revised Manuscript Received October 7, 2004 ABSTRACT: 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 w t%o fa 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 ∆V ≈ 1%, but that of free volume (hole) fraction by ∆h ≈ 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 ∆h is linearly related to the interlayer spacing, d 001. 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 ∆h result in relatively small changes of d001. Mechanical properties hardly correlate with either ∆h or d001, as polymer/ compatibilizer morphology and crystallinity complicate the behavior.

Free volume dependence of polymer viscosity

“…Evidently, the S-S eos well represents the observed dependencies. The recomputed values of P*, T*, and V* slightly differ from those reported previously (e.g., see Rodgers 1993;Utracki and Simha 2004a;Utracki 2005). The smallest difference is for LDPE60 (0.05, 2.03, and 0.68% for P*, T*, and V*, respectively), while the largest for PP (−6.4, 7.9, and 2.7% for P*, T*, and V*, respectively).…”

“…During the 30 odd years, the S-S theory has provided description of the PVT behavior in a single-and multicomponent systems, e.g., see (Simha et al 1984(Simha et al , 2001Papazoglou et al 1989;Utracki et al 2003;Tanoue et al 2004;Utracki and Simha 2004a;U t r a c k i2004a, 2006a)a s well as that of the cohesive energy density and internal pressure (Utracki and Simha 2004b;Utrack i2004b). Its great advantage is the explicit incorporation of the free volume parameter, h, which in turn may be used to interpret variety of dynamic properties, e.g., shear viscosity of neat liquids, their blends, composites, or foams (Utracki and Simha 2001b).…”

Free Volume in Molten and Glassy Polymers and Nanocomposites

“…As in the preceding publications, the experimental data at T > T g were fitted to the S-S equation of state following a two-step procedure (i.e., calculation of the initial P * , T * , V * parameters from the polynomial approximation of the S-S equation of state [Utracki and Simha, 2001a] and then optimizing the simultaneous fit of data to Eqs. (14.2) and (14.3) [Simha et al, 2001;Utracki et al, 2003;Utracki and Simha, 2004;Utracki, 2007]). Table 14.4 lists the P * , T * , V * parameters, the segmental molecular weight, M s , and the goodness-of-fit measures for V: σ = standard deviation and r 2 = correlation coefficient squared.…”

“…The studies not only collect information on the influence of P and T on the specific volume, density, compressibility, and other derivative properties, but in addition, using an adequate theory, they offer an insight into segmental interactions, segmental packing, the free volume, which in turn affects a host of properties, including thermodynamic equilibrium and nonequilibrium properties, such as cohesive energy density, solubility, viscosity, diffusivity, as well as the solid-state performance (i.e., physical aging, crystallization kinetics, etc.). For binary systems the PVT data analysis yields information about interactions between constituents: the polymeric matrix and entities dispersed in it: gas bubbles [Xie et al, 1992;Higuchi and Simha, 1996;Xie and Simha, 1997;Simha and Xie, 1998;Simha and Moulinié, 2000;Utracki and Simha, 2001b;Li et al, 2008], domains of immiscible polymers [Zoller and Hoehn, 1982;Jain et al, 1982;Maier et al, 1994;Srithawatpong et al, 1999;Utracki and Simha, 2001a], filler particles Simha et al, , 1986Papazoglou et al, 1989;Simha et al, 1989], or nanoparticles [Simha et al, 2001;Utracki et al, 2003;Nelson et al, 2004;Utracki and Simha, 2004;Bamji et al, 2005].…”

Rheology of Polymers with Nanofillers

“…The first few layers at z ≤ 6 nm are solidlike, with slow segmental mobility and low free-volume content. At increasing distance from the solid surface, 6 < z (nm) < 120, the segmental mobility exponentially increases, accompanied by a reduction of the shear viscosity from η ≈ 10 12 Pa·s to the value characteristic for the molten polymer [Simha et al, 2001;Utracki and Simha, 2004;Utracki, 2007]. This type of structure is also present in PNCs comprising intercalants and compatibilizers.…”