Advanced Materials Research Vols. 488-489

Abstract: A novel rubber bound antioxidant NR-g-HPM was prepared by melt grafting HPM (N-(4-hydroxyphenyl)maleimide) onto natural rubber in a brabender plasticorder. HPM was synthesized from p-aminophenol and maleic anhydride. The yield was found to be over 80%. The grafting products were observed with FTIR spectroscopy and TGA. The ageing resistance of natural rubber vulcanizates using NR-g-HPM was studied. It was found that an optimal amount of NR-g-HPM (6 phr) gave about 25% better tensile strength and elongation at break as compared with conventional BHT addition, for filled natural rubber after 48 h of accelerated aging.

Abstract: Fluorescent acrylamide water soluble macromer was synthesized from dimethylaminopropylmethacrylamide-9-(chloromethyl)anthracene quaternary ammonium salt monomer using an inverse emulsion polymerization method. It was initiated by benzoylperoxide and stabilized by a co-emulsifier system consisting of Span®80 and Tween®60 dispersed in a continuous phase of cyclohexane with HLB value of 6.42. The polymerization was done at 80°C for 4 hours. The obtained macromer exhibited similar functional groups, ultraviolet-visible absorption and fluorescent emission but different solubility when compared to the monomer. Further analyses by proton nuclear magnetic resonance spectroscopy and mass spectrometry revealed the chemical structure of the macromer as a dimer of the monomer containing carcon-carbon double bonds.

Abstract: TiO₂/SiO₂ composite catalysts were prepared using two-step sol-gel method, with tetrabutyl titanate and tetraethyl orthosilicate as the main raw materials, and its photocatalytic properties for degradation of active brilliant red X-3B solution were researched throuth Ti:Si molar ratio, calcined temperature, initial concentration and photocatalyst dosage. The results indicate that the TiO₂/SiO₂ composite catalysts prepared with Ti:Si molar ratio of 6, calcination at 500°C have the best photocatalytic activity, and the photocatalytic activity of the composite materials is higher than that of pure TiO₂ under the same conditions; moreover, it was found that degradation rate of active brilliant red X-3B solution increased with its lower initial concentration, and the optimum dosage of composite photocatalysts is 1.6g/L when the initial concentration of active brilliant red X-3B solution is 25mg/L.

Abstract: In the present work, we have fabricated Sn_0.91Co_0.05Ce_0.04O₂ (SCC54) and Sn_0.91Fe_0.05Ce_0.04O₂ (SFC54) nanorods by a chemical route similar to sol-gel method. X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, photoluminescence (PL) and magnetic measurements are used to characterize these nanorods. XRD pattern shows the polycrystalline nature of rods and TEM confirms that the diameter of rods lie in the range of 15-20 nm and length 100-200 nm. It is observed that on Ce³⁺ co-doping, nanoparticles assembled themselves into rod like structures. The SCC54 and SFC54 specimens exhibit room temperature ferromagnetism. Their saturated magnetic moment and phase transition temperature is sensitive to their size and stoichiometric ratio. Raman spectroscopy shows an intensity loss of classical cassiterite SnO₂ vibration lines, which is indication of significant structural modifications like crystallinity and nano metric size effects on the vibrational properties. From PL spectra, an intense blue luminescence centred at a wavelength of 532 nm is observed in the prepared SnO₂ nanostructures, attributed to oxygen-related defects, introduced during the growth process.

Abstract: This paper presents a vibration analysis of sandwich beams with functionally-graded skins containing edge cracks. Finite Element models of FGM sandwich beams are created with different depths and locations of the edge-cracks, and the first four natural frequencies of the beam are obtained for each crack configuration. The integrity of the data is validated for the FGM skins in comparison to a previously published reference. Finally, an inspection is conducted on the data to show the influences of the location and depth of cracks and material properties on the flexural vibration characteristics of cracked FGM sandwich beams.

Abstract: In this paper, the fatigue comparative test includes two groups of crankshafts, one group with surface rolling process and the other not, has been finished. And the test results are analyzed. The parent standard deviation test shows that there is not effect of surface rolling process impact on the uniformity of crankshaft fatigue strength. But it is sure that there is the impact of surface rolling process impact on the average of crankshaft fatigue strength by the average maternal test. So the surface rolling process can be used to improve crankshaft fatigue strength.

Abstract: Effect of the two-step solution heat treatment on the microstructure of semisolid cast 7075 aluminium alloy has been studied. The microstructure of the as-cast specimens mainly consisted of matrix-α (Al) and grain boundary (GB)-eutectic phase (α-Al + Mg(Zn,Cu,Al)₂). After solution treating, coarse black particles were found to form in the single-step solution treated specimens at the condition of 450 °C for 8 h and 480 °C for 1 h, respectively. Two-step solution heat treatment resulted in the reduction of coarse black particle formation while maintaining the same amount of eutectic MgZn₂ phase dissolution as the high temperature single-step solution treatment. Therefore, the two-step solution heat treatment enables alloying elements dissolved into the matrix without overheating and hence decreases coarse black particles. The optimum two-step solution heat treatment condition derived from this study was 400 °C for 8 h + 450 °C for 4 h.

Abstract: Concrete permeability is one of the key properties of concrete which largely effects concrete durability. Conventionally concrete permeability is considered as a function of water to cementitious materials ratio. But aggregate being the major constituent of concrete, was found to have considerable effects on various properties of concrete. In this research the effects of aggregate gradation on concrete permeability have been examined for two different types of cement. Total twenty concrete mixes were prepared using two different types of aggregate gradations, CEM I and CEM II/B-M cements. Concrete permeability measured in terms of depth of water penetration under pressure as per the standard EN12390-8. It has been found that concrete mixtures having same w/c ratio and keeping all other properties same, may have different permeability only because of different aggregate gradation. This article also features the use of concrete compressive strength as an alternative parameter for controlling concrete permeability based on the test results.

Abstract: Foamed concrete is material that can be used in wide range of constructions and produced in high density. This investigation examined effect of chopped Polypropylene Fiber (PF) that mixed into admixture concerning strength of foamed concrete high density. Mechanical test were performed to measure effect of PF on improving compressive and splitting tensile strength. Result indicate that PF significantly improving compressive strength and behavior of PF where drawn into foamed concrete similarly with normal concrete. The fibrillated PF has been occurred and reduced the micro crack of matrix and prevented propagation crack growth. The presence of PF improved splitting tensile strength was not significantly. Influence of porous of foamed concrete is considered. Scanning Electron Microscope (SEM) exhibits condition microstructure of foamed concrete reinforced PF that alter microstructure, especially interfacial bonding due to PF presence.

Abstract: We investigated self-compacting concrete (SCC) mixtures containing rice husk ash (RHA) from electric power plants. Type 1 Portland cement (OPC) was partially replaced by RHA at levels of 0%, 10%, 20%, or 40% of the total weight of the binder materials (OPC or RHA, 275, 325, or 375 kg/m³). The mixtures were adjusted to maintain slump flow diameters of 50 ± 2.5 or 60 ± 2.5 cm. The RHA was in the form of partially amorphous silicon dioxide (SiO₂) particles with an equivalent volume mean particle size of 24.32 µm. Increasing the RHA fraction resulted in a decrease in unit weight and an increase in the corresponding water/binder ratio and T₅₀ V-funnel times. Use of 20% RHA produced a material with a long-term compressive strength similar to the control SCC.