جستجوی مقالات مرتبط با کلیدواژه "نانوکامپوزیت هیبریدی" در نشریات گروه "فنی و مهندسی"

In this research hybrid nanocomposite coating of Ni-P/Al2O3-SiC and Ni-P coating were codeposited and deposited by electrodeposition on copper substrate. Electrodepositions for both cases was done by DC current. Sic nanoparticles sizes and Al2O3 nanoparticles sizes which were used for preparing nanocomposite bath, were respectively 55nm and 50nm. Charactrizaton and surface morphology of coating were done by scanning electron microscopy and energy dispersive spectroscopy.The tribological behavior of the coatings were evaluated by pin-on-disc test, and microhardness of coating were also evaluated by Vickers microhardness test. Morphology of surface coating was evaluated by optical electron microscopy. Results show that adhesion of hybrid nanocomposite coating on copper substrate is perfect. Participation of nano Al2O3 particles and nano SiC particles, causes improvement in the microhardness and wear resistance of hybrid nanocomposite coating. High strength of nano Al2O3 particles and nano SiC particles, improved the microhardness and wear resistance of hybrid nanocomposite coating. Also, increases in current density for electrodeposition improve microhardness of Ni-P coating and Ni-P/Al2O3-SiC coating.

This contribution concerns preparation and characterization of low-density polyethylene (LDPE) melt-mixed blends in the presence of organically-modified montmorillonite nanoclays and silane-modified nano perlite. Dispersion state of hybrid nanofillers was observed by scanning electron microscopy (SEM) technique. A significant increase in average roughness of fracture surface of polyethylene with addition of hybrid nanofillers and intensive ridges and valleys are observed in the samples. Crystallization and melting characteristics of LDPE nanocomposites reinforced by hybrid nanoclay/nanoperlite were studied by differential scanning calorimetry (DSC) in isothermal mode. Hybrid nanofiller incorporation increased crystallization and melting temperature which can be related to high interaction between polymeric chains and hybrid nanofillers. The results of mechanical investigation revealed that Young’s modulus and tensile strength of LDPE are improved with introduction of hybrid nanofiller. Six constitutive models, Yeoh, Arruda-Boyce, Mooney-Rivilen, polynomial, Van der Waals, and Odgen were applied to investigate the stress-strain behavior of LDPE/nano clay/nano perlite nanocomposites. It was concluded that the ability of these models to predict the true behavior of the nanocomposite samples directly depends on the amount of hybrid nanofiller. Results showed that Arruda-Boyce, Vander-Waals, Yeoh and Mooney-Rivlin models show more deviation from experimental data in all nanohybrid filler content, whereas the others, Ogden, polynomial (2), can be used for all samples.

Mechanical properties of epoxy and glass/epoxy filled with 0. 25، 0. 5 and 1 vol% of TiO2 nanoparticles have been studied using tensile and three-point bending tests. For the TiO2/epoxy nanocomposites، the results showed that the strength and stiffness were improved، though the strain at ultimate strength point and breaking strain decreased. Moreover، the hybrid nanocomposites composed of 4 layers of woven E-glass fabric and TiO2/epoxy matrix were fabricated and cut onaxis and 45° off-axis by water jet. The results of tensile and three-point bending tests indicated a remarkable improvement in the strength and stiffness that could not be related to the mechanical improvement of the matrix. The samples containing 1 vol% nano TiO2 were improved relative to samples without the nanoparticles. The tensile strength of the on-axis and off-axis samples containing 1 vol% TiO2 increased by about 25. 9% and 17. 9%، in the order given، compared to that of the glass/epoxy specimens. In three-point bending test، the strength of the on-axis and off-axis specimens was improved 26% and 23. 2%، respectively. In addition، the tensile stiffness of the onaxis and off-axis samples containing 1 vol% TiO2 increased، respectively، by about 14. 4% and 17. 5% compared to that of the glass/epoxy specimens. Also for the same on-axis and off-axis samples the three-point bending stiffness increased about 19. 8% and 14. 6%، respectively. The whole investigation on the microstructure of the hybrid nanocomposites illustrated that stronger interfaces between the fiber and TiO2/epoxy matrix were formed and improvement was noticed on mechanical properties of ternary composite compared to those of the fiber/epoxy composites. The analysis of damage zones of hybrid nanocomposites showed that the surface area of the damaged zone declined considerably due to the brittle behavior of TiO2-filled specimens but the area below the stress-strain curve، showing energy absorption during the test، increased.

polyacrylamides are water soluble macromolecules. These polymers are widely used for flocculation, separation and treatment of solid-liquid phase materials. In this research, organic-inorganic hybrid of polyacrylamide/silica nanoparticle is prepared via radical polymerization. First, the silica nanoparticle surfaces were modified by 3-methacryloxypropyltrimethoxysilane as coupling agent using a sol-gel technique in aqueous media in acidic condition. Afterwards, the modified nanoparticles are copolymerized by acrylamide monomer in presence of a peroxide initiator during a free radical polymerization. The chemical structure of the prepared modified nano-silica as well as polyacrylamide nanocomposite was studied and confirmed by FTIR spectroscopy technique. The morphology of nanocomposite was investigated by scanning electron microscopy. The SEM micrograph showed that the surface of the composite did not display any phase separation. Nanoparticles distribution was investigated by SEM-EDX technique. The results showed a uniform distribution of particles throughout the polymer bulk. TEM analysis showed the presence of silica nanoparticles in bulk of polymer which is an indicative of suitable dispersion of nanoparticles. The thermal stability of hybrid nanocomposite with that of polyacrylamide was compared by TGA technique. The higher thermal stability of hybrid nanocomposite with respect to homopolymer is indicative of a reaction between the modified nanoparticles and polyacrylamide chain. The presence of silicaparticles in copolymer was also confirmed with EDX analysis in ash content of hybrid nanocomposite.

In this research, novel hybrid nanocomposite containing iron modified titanium dioxide and tetraisoindole organic pigment has been synthesized and characterized. Modified nanoparticles and hybrid nanocomposite have been characterized by X-ray diffraction (XRD), FT-IR spectroscopy, energy dispersive X-ray (EDX) analysis, BET surface area determination, diffuse reflectance spectroscopy, simultaneous thermal analysis (TG, DTA) and transmission electron microscopy (TEM). The results confirmed the formation of the hybrid nanocomposite containing iron modified titanium dioxide and tetraisoindole organic pigment with the pure anatase phase. The TEM micrograph displayed that particle sizes of the hybrid nanocomposite were about 25 nm. The band gap energy of the hybrid nanocomposite was about 2.53 eV that has been decreased significantly in comparison with modified titanium dioxide nanoparticles (3.10 eV) and pure titanium dioxide (3.66 eV). Hence, synthesized hybrid nanocomposite with absorption edge in the visible region is much appropriate for optical applications of photocatalyst and photovoltaic under solar light irradiation.