Polypropylene (PP)-clay nanocomposites were obtained and studied by using three different coupling agents, glycidyl methacrylate (GMA), acrylic acid (AA), and maleic anhydride (MA). Three different clays, natural montmorillonite (Cloisite Naϩ) and chemically modified clays Cloisite 20A and Cloisite 30B, have also been used. Nanocomposites were prepared by melt-blending in a twin-screw extruder using two mixing methods: two-step mixing and one-step mixing. The relative influence of each factor was observed from structural analysis by WAXD, POM, TEM, and mechanical properties. The results were analyzed in terms of the effect of each compatibilizing agent and incorporation method in the clay dispersion and mechanical properties of the nanocomposite. Experimental results showed that clay dispersion and interfacial adhesion are greatly affected by the kind of matrix modification. The polarity and reactivity of polar groups give as a result better interfacial adhesion and subsequent mechanical performance. PP-g-GMA and PP-g-MA were better compatibilizing agents than PP-g-AA. Better dispersion and exfoliation for the nanoclays were obtained when using two-step mixing than one-step mixing conditions.

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Summary: Linear low‐density polyethylene (LLDPE)/clay nanocomposites are obtained and studied by using a zinc‐neutralized carboxylate ionomer as a compatibilizer. LLDPE‐g‐MA is used as a reference compatibilizer. Two different clays, natural montmorillonite (Closite Na+) and a chemically modified clay Closite 20A have been used. Nanocomposites are prepared by melt blending in a twin‐screw extruder using two mixing methods: two‐step mixing and one‐step mixing. The relative influence of each compatibilizer is determined by wide‐angle X‐ray diffraction structural analysis and mechanical properties. The results are analyzed in terms of the effect of the compatibilizing agent and incorporation method in the clay dispersion, and the mechanical properties of the nanocomposites. Experimental results confirm that the film samples with ionomer show a good mechanical performance only slightly below that of the samples with maleic anhydride (MA). The two‐step mixing conditions result in better dispersion and intercalation for the nanofillers than one‐step mixing. The exfoliation of clay platelets leads to an improved thermal stability of the composite. The oxygen permeability of the clay nanocomposites, using ionomer as a compatibilizer, is decreased by the addition of the clay.TEM image of a PE/4 wt.‐% Closite 20A nanocomposite formed using ionomer.imageTEM image of a PE/4 wt.‐% Closite 20A nanocomposite formed using ionomer.

Cover:The picture on the cover shows the XRD patterns of polyethylene/clay nanocomposites using maleic anhydride and ionomer as compatibilizers after the first and second step of mixing through the extruder. It also shows TEM images of the clay dispersion in the samples with no compatibilizer and when using maleic anhydride and ionomer as compatibilizers. Further details can be found in the article by

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