A new family of thermoplastic nanocomposites based on isotactic polypropylene (iPP) and inorganic fullerene-like tungsten disulfide (IF-WS 2 ) has been successfully prepared. A very efficient dispersion of IF-WS 2 material was obtained by mixing in the melted polymer without using modifiers or surfactants. The addition of IF-WS 2 nanoparticles induces a remarkable enhancement of the thermal stability of iPP, as well as an increase in the crystallization rate of the matrix when compared with pure iPP. The nucleating efficiency of IF-WS 2 solid lubricant nanoparticles on the a-phase of iPP reaches very high values (60-70%), the highest values observed hitherto for polypropylene nanocomposites. The incorporation of IF-WS 2 has also been observed to increase the size and stability of the crystals formed. The melting behavior of the nanocomposites indicates the formation of more perfect crystals as determined by differential scanning calorimetry and time-resolved synchrotron X-ray scattering experiments. The new nanocomposites show an increase in the storage modulus with respect to pure iPP measured by dynamic mechanical analysis. V V C 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45:

The intercalation capability of poly(styrene-b-ethylene butylene-b-styrene) (SEBS) in nanocomposites of isotactic polypropylene (PP) with 5 wt % of organically modified montmorillonite (C20A), prepared by melt blending, has been investigated. X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies have shown the presence of intercalated structures in the nanocomposite. In a previous research, we studied the intercalation capability of a commercial compatibilizer. 1 Those results, with the study we present in this work, allow us a better understanding of the mechanism of compatibilization and a deeper characterization of the structure and morphology of the nanocomposite. Scanning transmission X-ray microscopy (STXM) has been used. Because of the excellent chemical sensitivity and the high spatial resolution (∼40 nm) of this technique, we have proved that C20A is not in direct contact with the PP phase because the clay is always located inside the elastomer domains. The elastomer is surrounding the nanoclay, hindering the clay exfoliation and preventing its dispersion in the PP matrix. On the other hand, we have observed that the presence of the clay caused the SEBS particles to become elongated in shape and retarded the coalescence of the elastomer particles.

No abstract

We present a combined study by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning transmission X-ray microscopy (STXM) of the successful formation of nanocomposites of polypropylene with montmorillonite by melt processing, providing a complete picture of the intercalation and exfoliation processes taking place. The nanocomposites contained 5 wt % of an organically modified montmorillonite, and different amounts of polypropylene-graft-maleic anhydride, used as a polar compatibilizer. Microscopy reveals a complex morphology, with partial intercalation/exfoliation, which depends on the concentration of compatibilizer. STXM spectromicroscopy provides direct information of the presence of different polymer components at the polymer-silicate interfaces and details on the intercalation mechanism.

No abstract