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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.

A layer of a polyethylene-silver nanoparticles composite was deposited on a five layer barrier film structure. Different methods were used for the nanocomposite layer deposition: laminating, casting, and spraying over the multilayer structure. For the casting and spraying methods, the silver nanoparticles were previously dispersed in the polymer solution, with the assistance of ultrasound energy. The effect of silver nanoparticles and deposition method on the barrier, mechanical, and optical properties of the multilayer films was evaluated. The efficiency of silver ion release from the PE-Silver nanocomposite deposited on the multilayer films and their antimicrobial characteristics were investigated and discussed. The silver ion release and biocide effect of the multilayer films was found to be dependant on the silver nanoparticle content and on the deposition method used. The observed results could be helpful in the design of industrial films for packaging.

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Summary: The effect of peroxide functionalization of carbon nanofibers (CNF) on the physical and mechanical properties of polystyrene (PS)–CNF nanocomposites prepared via melt mixing was studied. The CNF functionalization was evidenced by Raman spectroscopy, comparing the ratio of peaks at 1 371 and at 1 590 cm−1 (peaks related to the disordered sp3‐hybridized carbon atom and to the graphitic structure of the sp2‐hybridized carbon atoms, respectively). The variation of the storage (E′) and tensile modulus (E) of the PS–CNF composites as a function of the untreated and peroxide treated CNF concentration were evaluated. Three different peroxide concentrations were used for treating the CNF. It was found that both E′ and E increase with CNF concentration and, in addition, increase further with the peroxide treated CNFs. Nonetheless, it was found that the greater the peroxide concentration used in treating the CNF, the greater the PS degradation via free radical attack on the polymer chain, with the corresponding negative effect on the storage and tensile modulus. Dispersion of the CNF was assessed using scanning and optical microscopy, and the positive effect of the peroxide treatment on the dispersion of the CNF is evidenced.Tensile stress‐strain behavior of PS/CNF nanocomposites.magnified imageTensile stress‐strain behavior of PS/CNF nanocomposites.