Synthesis and characterization of conducting polyaniline nanocomposites containing ZnO nanorods

Polyaniline (PANI) based nanocomposites filled with ZnO nanorods were prepared by the chemical oxidative method of the aniline in acid medium with ammonium peroxydisulphate (APS) as an oxidant. The composition, morphology and structure of the polymer and the nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), UV–vis spectroscopy and electrical conductivity. The characteristic FTIR peaks of PANI were found to shift to higher or lower wave number in PANI–ZnO composites due to formation of H-bonding. Different amounts of ZnO nanorods were used to verify this effect on the characteristics of the synthesized materials. These observed effects have been attributed to interaction of ZnO nanorods with PANI molecular chains. XRD results revealed that the crystallinity of PANI was more pronounced after addition of nanorods, while the intensity of the peaks increased by addition of ZnO nanorods. Electrical conductivity of the PANI–ZnO nanocomposite film was found to be smaller than that of the PANI film. The decrease of electrical conductivity in PANI–ZnO films as compared to PANI was attributed to the interfaces formed between oxygen of ZnO nanorods and hydrogen of PANI. Also, TGA results showed that the decomposition of the nanocomposite was less than that of pure polyaniline which confirms the successful fabrication of products. These conductive polymers can be used in commercial paints as an additive.     

Mechanical and wear properties of Al-Al3Mg2 nanocomposites prepared by mechanical milling and hot pressing

β-Al₃Mg₂ intermetallic was used as a reinforcing agent to improve the mechanical properties of an aluminum matrix. Different amounts of Al₃Mg₂ nanoparticles (ranging from 0wt% to 20wt%) were milled with aluminum powders in a planetary ball mill for 10 h. Consolidation was conducted by uniaxial pressing at 400°C under a pressure of 600 MPa for 2 h. Microstructural characterization confirms the uniform distribution of Al₃Mg₂ nanoparticles within the matrix. The effects of nano-sized Al₃Mg₂ content on the wear and mechanical properties of the composites were also investigated. The results show that as the Al₃Mg₂ content increases to higher levels, the hardness, compressive strength, and wear resistance of the nanocomposites increase significantly, whereas the relative density and ductility decrease. Scanning electron microscopy (SEM) analysis of worn surfaces reveals that a transition in wear mechanisms occurs from delamination to abrasive wear by the addition of Al₃Mg₂ nanoparticles to the matrix.