Nano Hybrids and Composites Vol. 21

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Authors: Júlio Cesar dos Santos, Luciano Machado Gomes Vieira, Túlio Hallak Panzera, Rodrigo Teixeira Santos Freire, André Luis Christoforo, Fabrizio Scarpa
Abstract: This work investigates the effect of silica nanoparticles functionalized with poly-diallyldimethylammonium chloride (PDDA) and silica microparticle inclusions (1.0 wt% and 3.5 wt%) on the impact resistance of hybrid carbon fibre reinforced composite laminates (HCFRCs) and tensile modulus of particle reinforced polymers (PRPs) via Full-Factorial Design of Experiments. The data were analysed with Analysis of Variance (ANOVA). The inclusion of particles led to reduced impact absorption of HCFRCs, except for composites with 1.0 wt% of silica in microscale, which provides an increase of 11.75% in the impact resistance. Microstructural analysis of fractured impact samples revealed pull-out as the predominant fracture mode in 1.0 wt% silica microparticle composites. Such mechanism leads to impact energy dissipation which may explain the increased impact resistance of these samples.
Authors: Georgios V. Seretis, Aikaterini K. Polyzou, Dimitrios E. Manolakos, Christopher G. Provatidis
Abstract: Stainless steel flakes-reinforced cast aluminum matrix composites were produced using aluminum alloy of 96.66% purity as matrix material and different steel flakes contents as reinforcements. Aluminum matrix specimens with no steel flakes fillers addition were also produced for performance comparison. All specimens were cast into a slightly heated rectangular quenched steel mold, the temperature of which was 35 °C. Both matrix aluminum specimens and aluminum matrix composite specimens underwent tensile and bending tests as well as hardness measurements and microstructural investigation. As observed through microstructural examination, the interdendritic regions do not seem to be affected by steel flakes addition on their at% chemical composition, which remains Al:Fe:Mn:Mg ; 92.28:3.75:2.96:1.01, but only on their size. An increase of the flexure strength of about 20% was achieved by steel flakes-reinforcement of the matrix aluminum. In the case of the highest wt% addition, groups of steel flakes of high directivity towards solidification kernels were observed. These steel flakes group formations resulted in an impressive hardness increase, performing as hard support elements.
Authors: Ahmed F. Mohammed, Wasan Rashid Saleh, Omar A. Ibrahim
Abstract: Semiconductor quantum dots (QDs) have attracted tremendous attentions for their unique characteristics for solid-state lighting and thin-film display applications. A simple chemical method was used to synthesis quantum dots (QDs) of zinc sulfide (ZnS) with low cost. The XRD) shows cubic phase of the prepared ZnS with an average particles size of (3-29) nm. In UV-Vis. spectra observed a large blue shift over 38 nm. The band gaps energy (Eg) was 3.8 eV and 3.37eV from the absorption and photoluminescence (PL) respectively which larger than the Eg for bulk. QDs-LED hybrid devices were fabricated using ITO/ PEDOT: PSS/ Poly-TPD/ ZnS-QDs/ with different electron transport layers and cathode of LiF/Al layers. The EL spectrum reveals a broad emission band covering the range 350 - 700 nm. Current-voltage (I–V) characteristics indicate that the output current is good according to the few voltages (8, 10, 11 and 12 V) used which gives acceptable results to light generation. Using TPBi and Alq3 as electron transport layer gives good enhancement to light generation in compares with that of QDs only. The emissions causing the luminescence were identified depending on the chromaticity coordinates (CIE 1931).
Authors: Mohammad Bellal Hoque, M. Sahadat Hossain, Abdul M. Nahid, Solaiman Bari, Ruhul A. Khan
Abstract: Pineapple Leaf Fiber (PALF)-reinforced polypropylene (PP) based composites were prepared successfully by conventional compression molding technique. Different percentages (25,30,35, 40 and 405% by weight) of fiber were used to prepare composites. Tensile Strength (TS), Tensile Modulus (TM), Elongation at Break (Eb %), Bending Strength (BS), Bending Modulus (BM) and Impact Strength (IS) were evaluated. The 45 wt% PALF/PP composite exhibited an increase of 132% TS, 412% TM, 155% BS, 265% BM, and 140% IS with respect to the matrix material (PP). Fourier Transform Infrared (FTIR) Spectroscopy was employed for functional group analysis of PALF/PP composites. For all percentages of fiber, the composites demonstrated lower water uptake. The fabricated composites were immersed in alkali solution (Sodium hydroxide solution, 3%, 5% and 7% by weight) for 60 min and showed low TS, TM and Eb% compared to control composites.
Authors: Mohammed Nasir Kajama, Yilmaz Yildirim, Usman Habu Taura, Alhaji Shehu Grema, Shehu Abdulrahman
Abstract: A dip-coating technique was applied to prepare a selective membrane on a commercial ceramic mesoporous support. Single gas components used for permeance and selectivity were CH4, CO2, H2, He, N2, and O2 (BOC UK) with at least 99.999 (% v/v) purity. The permeances and selectivities were obtained at room temperature and transmembrane pressure differences between 0.05 up to 5.0 barg. Gas permeation experiments showed the permeance of CO2 to be strongly influenced by surface diffusion mechanism. Single gas experiment showed linear flow dependence on the inverse square root of molecular weight at room temperature and 1.0 barg. The single gas selectivities were found to be higher than the ideal Knudsen separation mechanism. The highest CO2/CH4 selectivity value of 24.07 was obtained at 0.7 barg and room temperature.

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