Applied Mechanics and Materials Vol. 703

Abstract: In this study, novel solid–solid phase change materials (PCM) composed of polyacrylonitrile, binary of fatty acids ((blending of stearic acid (SA) and lauric acid (LA)) and zeolite molecular sieve (ZMS) were prepared by solution blending process. The structure and properties of the PCM were characterized using flourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), polarized optical microscopy (POM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TG), respectively. DSC analysis indicated that the crystallization latent heat of the PCM was 125.22 J/g and its phase transition temperature was about 17 °C. The temperature curve for step cooling of the PCM showed that it’s holding time achieved 1 480 s, which explains that the PCM had excellent heat-insulating properties. Based on all results it can be concluded that the novel PCM can be considered as potential PCM for thermal energy storage.

Abstract: B₄C/Al composites of different boron carbide contenting were prepared by the liquid mixing method and hot-rolled to 3mm. Microstructure and mechanical properties of the rolled composite were analyzed after the stress relieving heat treatment. Results showed that: the distribution of boron carbide particles was uniform, and only a few particles appeared fractured. With Ti addition, a reaction product layer was fabricated surrounding B₄C particles, which acted as a diffusion barrier to separate B₄C particles from liquid aluminum to protect them. With the mass fraction of the B₄C particles increasing, it can improve the tensile strength but degrade the plasticity of the composites. The fracture surface of composites showed both ductile and brittle fracture characteristics and when the mass fraction of the B₄C particles increased the ductile fracture feature decreased.

Abstract: In this investigation, nanoSchiff bases Cobaltic complex was synthesized and used as the initiator in the copolymerization of carbon oxide and propylene oxide (PO). The nanoCobaltic complex was characterized by infrared spectroscopy (IR), and nuclear magnetic resonance spectroscopy (NMR). The influences of different factors, including reaction time, reaction temperature, and pressure of CO₂ on the synthesis of polycarbonate were described. The results show that nanoCobaltic complex could be successfully applied in the copolymerization of CO₂ and PO. The optimum conditions of the polymerization, which include CO₂ pressure of 30 bar, reaction temperature of 80 °C, and reaction time of 3 hours.

Abstract: In this paper, the polished specimens of high Zn content Al-Zn-Mg-Cu alloy after various aging treatments were immersed in 3.5 wt.% NaCl for up to 240 mins. The development of corrosion was monitored using scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX). There are two stages during the corrosion process, the first stage of attack started with localized corrosion of trenching around the Al-Zn-Mg-Cu particles. In the second stage the pitting corrosion appeared at the grain boundaries, and then developed into intergranular corrosion. This phenomenon is related to the potential difference between the matrix and the precipitates.

Abstract: Under the acidic condition, 6-gingerol (C₁₇H₂₆O₄) reacted with hydroxylamine to generate 6-gingerol oxime (C₁₇H₂₇NO₄). Single-crystal X-ray diffraction with CuKα radiation (λ = 1.54184 Å) revealed the crystal belongs to the orthorhombic system, the space ground is P2₁2₁2₁ with a = 5.24240(10), b = 25.7792(4), c = 25.9824(5) Å, V = 3511.39(11) ų, Z = 8, Mr = 309.40, Dc = 1.171mg/mm³, μ = 0.669mm^-1, S = 1.035, F(000) = 1344.0, the final wR₂ was 0.1132 (all data) and R₁ was 0.0412 [I>2σ (I)]. Two molecules compose one monomeric unit in the crystal. And the hydrogen bonds construct the dimer and the integral crystal spacial structure. The antioxidant activity of the 6-gingerol oxime was tested by the scavenging effect on DPPH radical and potassium ferricyanide reducing power test while Vitamin C was regarded as the comparison. The IC₅₀ of the oxime for the scavenging effect on DPPH was 0.0471 g/L which was less strong than Vitamin C. The reducing power of Vitamin C was about three times powerful than the 6-gingerol oxime.

Abstract: A Na–ion conducting solid electrolyte system was prepared by using ball milling and sintering method. The electrical conductivity study was carried out as a function of NaI concentration by Electrical Impedance Spectroscopy technique and the maximum conductivity of (1.02±0.19)×10^-4 S cm⁻¹ at room temperature was obtained for the composition 0.50 NaI:0.50 Na₃PO₄. Further characterization was performed by using and Infrared (FTIR) technique. From FTIR spectra, the variation in the peak intensity and shifting is observed due to the presence of P–O and PO₄³⁻ bands that had been shifted indicating changes in polyhedral structure which in turn led to the formation of conducting channel by corner sharing or through edges. The ionic transference number was found in the value of 0.92 which suggests that ions are the charge carriers. The optimum composition with the highest conductivity of the sample considered as a good candidate to be used as solid electrolyte in solid state sodium battery. The sodium battery with configuration: Na/NaI–Na₃PO₄/V₂O₄ was tested by the discharged characteristic at a current of 1.0 μA. The solid state sodium batteries exhibited a discharge capacity of 144mAh/g.

Abstract: This paper proposes to fabricate thermal insulation structure between different regions with different temperature need for maintaining the biochemical reaction on a chip. It will reduce the heat transfer between different temperature regions, and be helpful to realize the temperature control of different regions of the chip. The fabrication experiment of the thermal isolation hole/cavity by PECVD SiC film deposition and the parylene-C film deposition experiment were performed. This kind of heat insulation structures would also ensure the strength of such devices.

Abstract: The blends of Nylon 6/Acrylonitrile-Butadiene-Styrene (ABS) with styrene-maleic anhydride (SMA) was prepared by melt blending as the compatilizer. Mechanical properties, dynamic mechanical analysis (DMA) and fracture appearances were determined. It was found that the impact and tensile strength firstly increased and then decreased along with the increase of the SMA content. The properties reached maximum values when the content of SMA was 1.5%. The results of DMA and scanning electron microscope (SEM) indicated that the addition of SMA can effectively enhance the compatibility of Nylon 6 and ABS. Key words: Nylon 6, ABS, SMA, blends, modification

Abstract: Bi_0.94Ce_0.06Fe_0.97Ti_0.03O₃ and Bi_0.94Ce_0.06Fe_0.97Ti_0.03O₃/Bi_3.15Nd_0.85Ti₃O₁₂ double-layered thin films were fabricated via sol-gel process on Pt/Ti/SiO₂/Si substrates. The influence of Bi_3.15Nd_0.85Ti₃O₁₂ buffer layer on microstructure and electrical properties of Bi_0.94Ce_0.06Fe_0.97Ti_0.03O₃ thin films were investigated in detail. Well-saturated P-E hysteresis loops can be obtained in Bi_0.94Ce_0.06Fe_0.97Ti_0.03O₃ films with Bi_3.15Nd_0.85Ti₃O₁₂ buffer. The remnant polarization (2P_r) of the double-layered thin films is 112 μC/cm². The coercive field (2E_c) of double-layered films is 672 kV/cm, which is much lower than that of the Bi_0.94Ce_0.06Fe_0.97Ti_0.03O₃ thin films. The leakage current density of Bi_0.94Ce_0.06Fe_0.97Ti_0.03O₃/Bi_3.15Nd_0.85Ti₃O₁₂ double-layered thin films is 4.12×10^-5 A/cm².