Argon surface plasma treatment (APT) of poly(propylene)/silver (PP/Ag) and poly(propylene)/ copper (PP/Cu) nanocomposite improves their antibacterial properties against pathogenic bacteria. Dispersions of PP/Ag and PP/Cu nanocomposites were prepared by sonication assisted melt mixing 0.05, 0.5, and 5 w/w% metal nanoparticle/polymer compositions, and then melt casted to form films that were surface treated with argon plasma. Scanning electron and atomic force microscopy showed that APT increase the surface roughness and the exposed nanoparticles. Also, APT produced implanted oxygen and nitrogen species as demonstrated by XPS analysis and enhanced the surface wettability. Antibacterial activity (AA) against S. aureus and P. aeruginosa of the plasma treated NC films was significantly increased in all conditions tested such as NP loading and interaction time; copper NCs were more effective than silver NCs. Surface activation of the PP/Ag and PP/Cu NC films by APT is a viable technique to increase the antibacterial activity of nanocomposites, an important issue in medical and health care applications.

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Carbon nanofibers (CNF) were modified via plasma assisted polymerization in a specially designed reactor. The effect of the plasma reactor conditions, such as power and time, on the extent of the CNFs modification was examined. Polystyrene (PS) coated nanofibers plus PS polymer were then processed in a Brabender torque rheometer mixing chamber to obtain PS/ CNF nanocomposites, with 0.5, 1.0, 3.0, and 5.0 wt % of CNF. The effect of the plasma treatment on the dispersion of the nanofibers and on the compatibility between the nanofibers and the polymer matrix was also examined. Modification of the CNFs was assessed by measuring the contact angle of water in a ''bed'' of nanofibers and by examining its dispersion in several solvents. The morphology of PS/CNF nanocomposites was studied through scanning electron microscopy (SEM). Contact angles decreased in all cases, indicating a change in hydrophobicity of the modified CNFs. This change was confirmed in the CNF dispersion tests in several solvents. SEM micrographs show the difference between the original and the PS coated CNF. In addition, fractured samples show the effect of this treatment, in the sense that the CNF seem to be completely embedded in the polymer matrix, which clearly indicates the high compatibility between the PS and the modified (PS coated) CNF. As a consequence, a much better dispersion of the treated CNF was observed. Finally, the tensile modulus of PS/CNF composites increased slightly with respect to PS when using untreated CNFs, but more than doubled when using plasma treated CNFs.

Although the porosity in Al-SiC metal matrix composites (MMC) can be diminished; its existence is unavoidable. The purpose of this work is to study the effect of porosity on Young's modulus of SiC reinforced aluminum matrix composites. Finite element analysis is performed based on the unit cell and the representative volume element approaches. The reliability of the models is validated by comparing the numerical predictions against several experimental data ranging in lowand high-volume fractions and good agreement is found. It is found that despite the stress transfer from the soft matrix to the reinforcement remains effective in the presence of pores, there is a drop in the stress gathering capability of the particles and thus, the resulting effective elastic modulus of composite decreases. The elastic property of the composite is more sensitive to pores away the reinforcement. It is confirmed, qualitatively, that the experimentally reported in the literature decrease in the elastic modulus is caused by the presence of pores.

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Copper nanoparticles (Cu-NPs) with sizes lower than 31 nm were prepared by wet chemical reduction using copper sulfate solution, hydrazine, and mixture of allylamine (AAm) and polyallylamine (PAAm) as stabilizing agents. The use of AAm/PAAm mixture leads to the formation of Cu and CuO nanoparticles. The resulting nanostructures were characterized by XRD, TGA, and TEM. The average particle diameters were determined by the Debye-Scherrer equation. Analysis by TGA, TEM, GS-MS, and1HNMR reveals that synthesized NPs with AAm presented a coating with similar characteristics to NPs with PAAm, suggesting that AAm underwent polymerization during the synthesis. The synthesis of NPs using AAm could be a good alternative to reduce production costs.

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