Advanced Materials Research Vols. 183-185

Abstract: A novel rigid polyurethane foam was prepared by using epoxidized soybean oil (ESBO) instead of 50% of petrochemical polyol-835 in the B-side of foam formulation. Although there are no significant variations in density and compressive strength of ESBO-based rigid foam compared with petrochemical-based rigid foam, better thermal stability and higher melting point (of polyether section) were attained and proved by TGA, DTG and DSC analysis. Presumably, the improved characterizations could be originated from the long carbon chain of ESBO and especially the oxazolidone structure as indicated in FTIR spectrum.

Abstract: Copper slag was used to prepare copper powder by way of slurry electrolysis, and the copper powder was used to fabricate copper matrix composite materials reinforced with chemical plating surface modified alumina particulates. Alumina particulates were pretreated in ultrasonic field by chemical copper plating in order to make alumina particulates covered with a layer of copper film and form Al2O3/Cu composite powders. Copper matrix composite materials strengthened with alumina particulates were synthesized by means of pressure molding and sintering. Microstructure of copper matrix composites was researched by means of SEM. SEM analysis shows that alumina particulates distribute in the copper-based body evenly, and combine with copper closely. The effects of sintering temperature, pressure and alumina content on the compactness and hardness of copper matrix composites were studied by orthogonal tests. The compactness of composites increases with the sintering temperature and pressure increasing, and decreases with the alumina content increasing. The hardness of composite materials increases with the sintering temperature, pressure and alumina particulates increasing.

Abstract: The apparent reactivity ratios of hexafluoropropylene (HFP)/vinylidene fluoride (VDF) emulsion copolymerization were studied by nonlinear fitting according to the copolymer composing equation, which, according to the calculation, are 1.88 and 0.86 respectively. The constitution of mixed gaseous monomers was measured through the gas chromatography. The copolymer compositions before and after reaction were measured by ¹⁹F-NMR. The calculated contents of VDF and HFP have nice accordance with the results from ¹⁹F-NMR analysis, which demonstrates that the method reported here is fairly reliable, and shed a light on the industry-scale consideration for the emulsion copolymerization of HFP and VDF.

Abstract: Ploy-high-ferric-silicic coagulant was prepared using the fly ash extract and potassium ferrate. The flocculation process of treatment lead wastewater by this coagulant with various Si/FeO₄^2- ratios and salt-basicity at different pH and dosage were studied by jar test. The results showed that color, turbidity and Pb²⁺ removal efficiency are excellent and treatment effects are stable in treatment lead wastewater, especially the removal of Pb²⁺ has been up to 96% more. The comparison on coagulation between poly-high-ferric-silicic and other coagulants, the poly-high-ferric-silicic dosage is low and adapt to a wide PH. Therefore, by comparison, the poly-high-ferric-silicic is a superior coagulant in lead wastewater treatment.

Abstract: The dielectric and pyroelectric properties of ferroelectric thin films coated with two semiconducting electrodes are studied in the frame work of Ginzburg-Landau-Devonshire theory. Due to the depolarization effect produced by the surface polar charges cannot be completely screened, the contribution of the semiconducting electrodes is included in the free-energy functional. The dielectric susceptibility and the pyroelectric coefficient are calculated respectively as functions of temperature and film thickness. A comparison with the results of investigations performed for perfectly conducting electrodes shows that the effects of semiconducting electrodes can induce a transition from the ferroelectric phase to paraelectric phase, changing the phase transition from the second order to first order, and greatly improving the dielectric susceptibility and pyroelectric coefficient.

Abstract: Well-aligned ZnO nanorod arrays with 100-200nm diameter and about 1μm length were vertically grown on quartz substrate at relatively low temperature by a solution deposition method. The effects of reactant ratio, water-bath temperature, growth time on crystal structure were discussed. Microstructure of the arrays was investigated using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM), optical properties were examined using fluorescence spectrophotometer. The results show that a Zn/C₆H₁₂N₄ molar ratio of 1:1, bath temprature 70°C, growth time of 24h are the optimal condition for the preparation of densely distributed ZnO arrays. XRD and FE-SEM analysis confirmed that the ZnO nanorod is a single crystal with a wurtzite structure and the photoluminescence (PL) spectra exhibit coexistence properties of ultraviolet (UV), blue and green emissions.

Abstract: Polyurethane (PU) with mixed poly(ethylene glycol) / poly(ε-caprolactone) (PEG/PCL) soft segments is a representatively kind of degradable polyurethane material. Polyurethane foams (PUF) with mixed PEG/PCL soft segments were synthesized by using one pot method, and their mechanical and dynamic mechanical properties were investigated. Influences of PEG/PCL weight ratio and molecular weight of soft segments on PUF's mechanical and dynamic mechanical properties were studied. The results showed that: with increasing content of PCL, PUF's tensile strength, elongation at break, stress at certain tensile/compressive strain and storage modulus increased gradually; with increasing molecular weight of soft segment, PUF's elongation at break increased, but tensile strength, stress at certain tensile/compressive strain and storage modulus all decreased accordingly; glass transition temperature (T_g) of PUF with various soft segments decreased according to the following sequence: PEG-400, PCL-210N, PEG-1000 and PTMG1000; loss factor of PUF with PEG/PCL mixed soft segments was higher than that of PUF with individual PEG or PCL soft segments.

Abstract: Friction stir blind riveting (FSBR) is a new joining process which eliminates the need to predrill a hole for rivet insertion. Lap joint friction stir blind riveting the plates made of high strength steel DP600 (1 mm) and magnesium alloys AZ31B(3 mm) with different technological parameters was carried out. This study experimented with the strength and the morphology of the joint with different rotation speed and feet rates of the spindle rivet, and which material on bottom or top. The main results obtained are as follows: FSBR’s process of steel and magnesium alloy plate was quickly and successfully achieved. The maximum shear strength of the joint reached about 6.3KN and the fracture path was along the shank of rivet. When Mg plate is on top of the other, the spindle speed is 2,200rpm, and along with the increase of the feed rates, the gap of plates is decreased, the strength of joint is increased. When steel plate is on top layer, the spindle speed at 2,200rpm, the rivet can then plug into the plates with a feed rate at least 600mm/min, and the joint shear strength will become higher.

Abstract: The anodized Al alloy films are sealed in the alumina sol with anatase type of titanium oxide.Coloration experiment; acid drip test and self-cleaning efficiency are used as evaluation criterions. Orthogonal test of sol sealed films and Two Factor test are used to value the influence of technological parameters on properties of the sealed films. The results show that the corrosion resistance of sealed film doped with TiO₂ was superior to that of without in neutral saline water. Three-dimensional surface morphologies obtained by OLS3100 laser confocal scanning microscope (LSCM ) show that the sealed films with are smoother than ones without TiO₂ and its pits in the sealed film are less. The sealed films with TiO₂ have both corrosion resistance and self-cleaning effect.

Abstract: We studied the spontaneous crystallization behavior for 60.5SiO₂-2.5Al₂O₃-3P₂O₅- 18Na₂O-16RMgO-16(1-R)CaO system glasses during cooling of melts through changing the relative content of alkaline-earth oxides. Such compositional variation leads to the formation of different crystalline phases, as well as different degree of crystallization, with the help of X-ray diffraction (XRD), heat capacity (C_p) and scanning electron microscopy (SEM). It is found that the obtained glasses are opalescent due to formation of orthorhombic NaCaPO₄ during cooling when R≤0.5, and the degree of crystallization increases with substituting MgO for CaO. On the other hand, the spontaneous crystallized phases is hexagonal NaCaPO₄ for R=0.75 and is Na₂MgSiO₄ for R=1.0, respectively, and besides, the appearance become transparent.