Key Engineering Materials Vol. 818

Abstract: The results of a study on the removal of arsenic (As) contamination in soil using dracaena fragrans. In the research, this plant was planted on as – contaminated soil at five levels of concentration of 0 mg/kg, 100 mg/kg, 200 mg/kg, 300 mg/kg and 500 mg/kg. After 90 days experimental in the five concentrations the survival rate was 100%. However, as concentrations have a significant effect on growth parameters, especially in concentration 500 mg/kg, the growth of the plant showed marked signs of slow growth, the leaves were retracted. Analyzed results on as content in roots, stems, and leaves of plants at all experimental after 90 days show that there was a linear relationship between as content in different parts of the plants and in soil samples. At the experiment concentration 500 mg/kg, the concentration of as in roots was 15.7 mg/kg, that in stems was 4.4 mg/kg and that in leaves was 3.2 mg/kg. The amount of as accumulated in the roots had the highest percentage. There was 1.14 mg as had been removed by 209.1 g of biomass of dracaena fragrans after 90 days.

Abstract: Polypropylene is a widely used thermoplastic with high impact resistance and strong mechanical properties. Graphene has exhibited in a new generation of electronic component materials owing to its high thermal conductivity and low resistivity. In this study, a composite of graphene and polypropylene for injection molding purposes was created. In Taguchi method, an L9 orthogonal array for injection molding experiments was adopted. The process parameters included injection temperature (A), holding time (B), injection pressure (C), and graphene ratio (D). Optimal parameter combinations were determined according to resistivity, and the results were A3B2C1D3: 2956.333 MΩ by original and A1B2C1D3: 2802 MΩ Taguchi analysis, respectively, where the improvement was 5.2%.

Abstract: In a hybrid coupled wall (HCW), a steel coupling beam with a good shear performance can replace a concrete coupling beam. This is especially applicable for locations in which height restrictions do not permit the use of deep reinforced concrete beams or in which it is not possible to economically develop required capacity, stiffness, or deformation demands with concrete beams. In this study, a new type of connection design with a steel boundary element of hybrid coupled wall (SBE-HCW) was proposed, and a 23-story SBE-HCW structure was analyzed under both gravity and seismic load to examine the seismic performance using ABAQUS. The structural failure process, base shear force, vertex displacement, and damage distribution of core tube were investigated. The analysis results confirmed that the response of specimen exhibited good plastic deformation behavior under seismic, thereby satisfying the demands of seismic ductility design. The connection between the steel coupling beams and the shear walls in the specimen appeared to be intact. The analysis evidence indicated that the proposed connection detailing appeared to be effective.

Abstract: Nowadays, the fire behavior of polymer composite materials is a concern in automotive applications. Due to the flammability of this type of compounds, the present study focused on analyzing the influence of the flame retardants of aluminum hydroxide and magnesium hydroxide on the flammability index. A DOE was carried out using a complete factorial design using two categorical variables (type of resin and type of retardant at two levels) and one quantitative variable (volumetric percentage of the retarder for 3 levels). Twelve combinations of composite material were manually conformed maintaining the general volumetric fraction (30% reinforcement, 70% polymer matrix). Percentages of retardants (3.6 and 9%) were part of the volumetric composition of the matrix. The performance and evaluation of the flammability test was carried out under ISO 3795: 1989 and FMVSS 302. In addition, the average temperature inside the test chamber was measured to observe its behavior during combustion. The results showed that the flammability index was significantly reduced with the use of polyester resin with retarder aluminum hydroxide at any percentage and the highest temperature inside the chamber was produced by the combustion of the epoxy resin with 9% retardant of flame.

Abstract: A new generation of high energy materials depends on the use of Nano-particle oxides. Nano-scale copper oxide (nano-CuO) has large surface area and surface energy which is suitable for its application in the field of energetic materials. This manuscript reports a method for the synthesis of nano-CuO by a liquid-state reaction method. The prepared nano-CuO was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD) to check the particles size, purity and morphology of the crystals. The effect of Nano-CuO on the thermal behavior of AP was tested by differential scanning calorimeter (DSC). The results proved that the average particle sizes of the nano-cuo particles are in the range of 10-20 nm. The thermal degradation rate of AP was increased by 23% in the presence of 1% nano-CuO and the heat release was increased by 51%. It was concluded that nano-CuO could have obvious effect on the burning behavior, performance and combustion characteristics of the solid rocket propellants.

Abstract: A sacrificial anode cathodic protection method has been widely used in the steel pile by galvanic current by potential difference between sacrificial anode and corrosive structural steel. And, the sacrificial anode cathodic protection method have generally merits compared to impressed current method because it can be applied to everywhere which is not connected with electricity. However, when the steel piles of the pier are submerged in low conductivity solution mixed with fresh water and sea water, the structural steel piles mentioned above have not been protected occasionally perfectively due to decreasing of galvanic current caused by deposited with oxide film on the surface of anode. In this study, five types of samples which are added with NaCl(g) to Zn anode were prepared with ratio of NaCl(g)/Zn(g)x100(%). And galvanic currents, surface morphologies characteristics of these samples was investigated using electrochemical methods such as polarization curves, galvanic current and analysis of surface morphologies before and after reduction weight ratio test in order to evaluate the effect of addition of NaCl(g) affecting to quality of zinc anode. The 2.6 % sample added with NaCl(5g) showed the highest value of galvanic current density in 0.8% NaCl solution, however, the highest reduction weight ratio was also observed at the 2.6% sample. Therefore, it is considered that the higher galvanic current density, the higher reduction weight ratio, that is, the life of sacrificial anode is shorted with increasing of galvanic current. Moreover, all samples added with NaCl(g) to Zn sacrificial anode indicated higher galvanic current density compared to the sample with no addition of NaCl(g) in low conductivity solution. Eventually, it is supposed that the galvanic current can be increased with addition of NaCl(g) to Zn sacrificial anode in low conductivity solution.