X‐ray diffraction study of iPP/cand iPP/TiO₂ composites relating to micromechanical properties

Abstract

Composites of isotactic polypropylene with various contents of white clay or titanium dioxide TiO2 were prepared by extrusion molding. The extruded composites were melt‐pressed at two different temperatures, and, thereafter, either slowly cooled, or quenched to room temperatures. It is shown that the structure of all the samples, as revealed by wide‐angle X‐ray scattering and small‐angle X‐ray scattering (SAXS), depends on the processing conditions. The lack of SAXS maxima in the composites suggests that the presence of the microadditives hinders the stacking of iPP lamellae. Furthermore, the microindentation hardness H in the slowly cooled composites is influenced by the type and amount of the filler used. However, in the quenched samples H depends only on the amount of the filler used, and not on its type. In case of the quenched iPP/clay composites, the relationship between H and the Young's modulus E is found to be H/E ≈ 0.12, in good agreement with Struik's theoretical predictions of σe ≈ E/30, in consonance with results previously obtained for a series of polyethylene samples with different morphology. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Flow-induced crystallization of polypropylene in the presence of graphene nanoplatelets and relevant mechanical properties in nanocompsoite fibres

“…Previous works showed no obvious change in the crystallinity of PP/GnPs composites using very low quantity of GnPs [9,10,13,14,22] or for its similar platelet form filler, clay, in PP/clay nanocomposite fibres, even if the some compatibilizers was used [19,[41][42][43][44]. To our best knowledge, our DSC results have, for the first time, shown the flow-induced crystallization for PP/GnPs nanocomposite systems.…”

The role of the compatibilizer on the microindentation hardness of iPP/PC blends

“…In the preceding equation, Δ , as mentioned above, is the melting enthalpy for an infinitely thick crystal; σ e is the surface free energy and is the equilibrium melting point. For iPP, we have taken = 460.7 K and σ e = 100 erg cm −2 . The crystal thickness values for iPP derived from Eq.…”

Effect of compatibilizing agents on the physical properties of iPP/HDPE organoclay blends

“…Other systems have been studied by employing this technique, i.e., block copolymers [29], natural rubber blends [30], ethylene/1-octene copolymers and their blends with HDPE [31], new reversibly crosslinked isotactic PP (iPP)/LDPE blends [32], and composite materials with carbon black [33] or clay [34] as fillers. Moreover, polymer blends of recycled poly(ethylene terephthalate) (PET) with polyolefins (iPP or HDPE) have been examined [35], as well as iPP/clay and iPP/TiO 2 composites [36]. Finally, the microhardness technique has been also very useful to elucidate the microstructure of multilayered systems based on blends of crystalline and amorphous polymers [37].…”