Materials Science Forum Vols. 809-810

Abstract: In order to selectively separate luteolin from its crude solution, we synthesized luteolin molecular imprinted polymers (LMIP) with high recognition specificity for luteolin, using an imprinting technique. Luteolin was used as template, methanol as solvent, and N,N’-methylenebisacrylamide (MBAA) as the cross-linking. Then prepared LMIP were characterized and evaluated by scanning electron microscope (SEM) and equilibrium absorption experiments. The results showed that the cavities matching with the template molecules in size and structure were present in the LMIP. Adsorption dynamics analysis suggested that, when the adsorption time reached 4 h, the adsorption process had reached balance and the adsorption capacity was at steady state. The selective adsorption amount reached at 35.65 umol/g for the LMIP, while a lower value of 11.68 umol/g for the blank polymer (i.e. nontemplated). Relative to the corresponding blank polymer, LMIP had an excellent recognition to luteolin in methanol solution. Keywords: Molecular imprinting, Molecular recognition, Adsorbent, Luteolin

Abstract: The starch-based polyampholyte (SPAM) was synthesized by graft copolymerization of starch with acrylamide (AM) and acrylic acid (AA). The structural and chemical characteristics of the product, as well as its efficiency in slowing the nitrogen release and water evaporation in soil were examined. The slow-release effect of SPAM was better than starch, starch-g-SPAC (Sodium polyacrylate) and starch-g-PVAC (Polyvinyl ammonium chloride) for urea release, particularly when the pH of SPAM solution was equal to 5(approached or equaled to isoelectric point, IEP). These studies showed that the product with good slow-release and being environmentally friendly is biodegradable carrier materials.

Abstract: Two new kinds of Cholesteric cyclohexane-Containing Side-Chain Liquid-Crystalline Polysiloxanes (P_A and P_B) were synthesized via hydrosilylation reaction of polymethyl hydrogen siloxane with cyclohexane mesogenic monomers (M_A and M_B). The yield of P_A, P_B were 71.6%, 82.5% and 81.0%, respectively. The molecular structures of M_A and M_B, P_A and P_B were investigated by Fourier transform infrared spectroscopy (FTIR) and hydrogen-nuclear magnetic resonance spectra (¹H-NMR). The corresponding liquid crystalline phase type was also observed by polarizing optical microscopy (POM) and X-ray diffraction (XRD). The liquid crystalline phase behavior and thermal properties of the polymers were analyzed by differential scanning calorimetry (DSC). Results showed that M_A and M_B exhibited multicolor platelet texture of a blue phase and cholesteric phase, and the T_m and T_i of M_A and M_B increased with the increasing flexible chain length. The mesophase temperature range of P_A and P_B was broader than that of M_A and M_B. P_A exhibited a rare nematic phase----spherulite texture of polymeric smectic A phase. P_B were of cholesteric and nematic---- cholesteric phase. The T_m and T_i of P_A and P_B increased with the increasing flexible spacer groups.

Abstract: Fibri-form silica was extracted from short chrysotile fibers by mix-roasting with ammonium bisulfate. The fibri-form silica were characterized by X-ray fluorescence analysis (XRF), X-ray diffraction (XRD), thermogravimetry and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR) and N₂ adsorption isotherms. The results show that the fibri-form silica with disordered crystalline structure, but also in fibrous morphology. The surface area and pore volume of fibri-form silica are 181.66 m²/ g and 0.44 cc/ g, respectively. The structure of fibri-form silica is stable, no phase transformed from 50 to 1200 ^oC.

Abstract: Porous poly (1-naphthylamine) were synthesized by interfacial polymerization method. The effects of several reaction conditions including oxidant/monomer molar ratio, polymerization temperature and reaction time on the polymerization yield have been investigated. The highest yield of poly (1-naphthylamine) was up to 73% at oxidant/monomer molar ratio of 3 and polymerization temperature of 25 °C for over 20h. Using FT-IR and XRD to analyze the structure of the obtained polymer, the results show that the main mode of connection for 1-naphthylamine units was linking N to para-C and it formed amorphous polymer with some ordered strutures. The micro-morphology of the polymer observed by SEM was found to have irregular porous structure with pore size less than 5μm, which may be related to the “self-emulsion effect” during polymerization.

Abstract: Elucidation of the chemical structure changes that take place of high density polyethylene (HDPE) used as rotational packaging case by attenuated total reflection infrared spectroscopy (ATR-FTIR), when natural aging of Lasa Tibet and xenon aging. The variations of carbonyl index (CI), hydroxyl index (HI), branching degree (N) and crystallinity (Xc) have been studied from qualitative and quantitative. Finally, the correlations between natural and xenon aging have been closely followed. It found that the oxidation and growth of unsaturated compounds play a leading role in the natural aging progress, but the polymeric chain scission is weak effect. However, the samples show a slower growth of unsaturated compounds and a sharp increase in polymeric chain scission after xenon aging. The CI, HI and N increased generally in a line fashion after natural and xenon aging while the Xc changes little.

Abstract: The structural properties, elastic properties, mechanical stability, and phase transition of equiatomic Al-Fe-Ti-Cr-Zn-Cu high entropy solid solutions from binary (Al-Fe) to hexanary (Al-Fe-Ti-Cr-Zn-Cu) composition with pressure-induced have been analyzed using density functional theory calculations. The results indicate that the lattice parameters decrease, the mass densities increase with the pressure-increased. The mechanically stability may improve with the pressure increased appropriately for ternary Al-Fe-Ti and quaternary Al-Fe-Ti-Cr. The Young’s modulus has nothing to do with the pressure-induced, but the bulk modulus increases with the pressure increased. The elastic properties were also calculated using Voigt-Reuss-Hill (VRH) approximations. The brittle and ductile properties were studied by Poisson’s ratios and the ratios of shear modulus to bulk modulus. The calculated results of the enthalpy indicate that the binary to hexanary high entropy solid solutions transform the FCC structure to the BCC structure at a certain pressure.

Abstract: The solid bonds of multi-layer Fe₇₈Si₉B₁₃ metallic glass foils have successfully been produced by ultrasonic welding technology. The interface of weld joints was investigated by Optical micrograph (OM), scanning electron microscope (SEM) observation, micro-area X-ray diffraction (micro-XRD) and differential scanning calorimetry (DSC) analysis. The results demonstrate that no visible interface and defects were observed and the amorphous structure was maintained. The thermal properties of the joined metallic glasses were the same as that of the parent metallic glass. The formation of joining metallic glasses was attributed to the superplastic flow and the thermal stability at elevated temperatures in the supercooled liquid state. Ultrasonic welding as tack welding proposes an effective method for the preparation of bulk metallic glasses (BMGs) and lays the foundation for its future applications.

Abstract: A slow strain rate tensile (SSRT) test was carried out to investigate the stress corrosion cracking (SCC) behavior of the sensitized 304L austenitic stainless steels (ASSs) in alkaline solution (0.5M NaOH). Mechanical properties and fracture morphology evolutions of the 304L ASSs were studied as a function of temperature through slow speed tensile tester and scanning electron microscopy (SEM). The results showed that the tensile strength and percentage elongation after fracture significantly reduced as the test temperature rose. Fractographic examination revealed both ductile and brittle fracture features for the specimens tested in different environments. However, the proportion of brittle fracture characteristics changed with the temperature.

Abstract: In this paper, tensile properties at room temperature and bending rupture properties of single crystal aluminum wire, 4mm in diameter, fabricated by ohno continuous casting were studied, and its fracture was analyzed. The results showed that: Compared with polycrystalline aluminum samples, the yield strength of Ohno Continuous Casting single crystal aluminum changed little; Ultimate strength decreased by 42.7%; Elongation and reduction of area increased by 111.5% and 575%; Bending fatigue strength have been enhanced distinctly. Fracture of single crystal aluminum were flat tip shape, the slip line near fracture parallel to each other and uniformly distributed, the fracture is typical dimple structure and the dimple size were relatively uniform, appeared as parabolic.