Advanced Materials Research Vol. 528

Abstract: Poly (lactic acid) (PLA) has many potential uses, for example as packaging, textiles, biomedical fields, including suture, bone fixation material, drug delivery microsphere, and tissue engineering. However, PLA shows the poor toughness, slow degradation rate and relatively hydrophobic. The aim of this study was to investigate the ability of N-methyl-2-pyrrolidone (NMP) to improve the characteristics of PLA film. PLA films were prepared using a solvent casting method and their various properties were investigated. From tensile strength (TS), elongation at break (E) and young’s modulus (ε) determinations, the incorporated PLA films exhibited the softer behavior than plain PLA film. On the other hand, from the contact angle and surface free energy values, the PLA films incorporated with NMP could improve the wettability of solvents and also increased % water sorption (WS) and % weight loss (WL) than PLA films with NMP dose dependent. However SEM photographs revealed the more rather rough and cracked surface as the higher amount of NMP was incorporated in PLA film.

Abstract: In order to enhance the application of bulk metallic glass (BMG) as engineer material, it is necessary to develop appropriate bonding technology to solve the problems of size limitation and weldability. In this work, a friction welding set-up was constructed, and the Zr₄₁Ti₁₄Cu_12.5Ni₁₀Be_22.5 BMG rods were joined. The joint interface zone was examined by X-ray diffraction, Scanning electron microscope, Vickers Micro-hardness and Transmission electron microscope. The results showed that the BMG rods were successfully joined, where no crystallization and visible defects were observed. The welding joint maintained the amorphous structure except few nanocrystallines occurred. Then the temperature field simulation was executed using ANSYS finite element software to optimize the welding parameters. It indicated that friction time cannot exceed 0.25s under the given experiment conditions, otherwise the crystallization would occurred, which is in good agreement with the experiment. It is concluded that the temperature field simulation can be used to guide the experiment and the friction welding can be used to join the BMG.

Abstract: The aging hardened plastic mould steel 10Ni3MnCuAl after aging at 510 °C is investigated by scanning electron microscope (SEM), transmission electronic microscope (TEM) and three dimensional atom probe (3DAP). The results show that its microstructure is granular bainite after soluted. Its aging hardening is mainly due to the precipitation of a high density, nanoscale and fully coherent NiAl precipitation with the B2 structure for 4 h. Clusters associated precipitates from 3DAP results show that its aging hardening derives from multicomponent precipitate containing Fe, Ni, Al, Mn and Cu, and concentration of Fe decreases with the aging time, while that of Ni, Al, Mn and Cu are opposite, and the ratio between Ni and Al are roughly 1.

Abstract: The infrared absorption spectra of some saltwater pearl and shell are investigated; the micrographs of the pearl and nacre layer are viewed. The result shows that infrared absorption spectra of pearl and nacre comprise the spectra of nanophase CaCO₃ and other unidentified material, this can evidence that nacre is a kind of biologic composite material composed of nanophase calcium carbonate.

Abstract: The effect of self-generated seeded thermal hydrolysis factors, such as TiOSO4 solution concentration, grey aging time, volume ratio of TiOSO4 to pre-adding water, and heating rate on high-purity TiO2 size for PTC thermistor were studied. The samples were characterized by particle size distribution, and SEM. The results show that with increase of TiOSO4 solution concentration, the high-purity TiO2 size decrease gradually, but with increase of grey aging time and volume ratio of TiOSO4 to pre-adding water respectively, the high-purity TiO2 size also increase. The suitable TiOSO4 concentration is 160g/l, grey aging time is 15min, the optimum volume ratio of TiOSO4 to pre-adding water is 4.0:1 and heating rate should be 1.5°C/min.

Abstract: In this study, different lipophilic groups from 3-aminpropyltriethoxysilane (APTES) and 3-glycidoxypropyltrimethoxysilane (GPTMS) were used to alter the surface structure of nanocrystalline cellulose (NCC). The diversifications of NCC surface resulted from modifiers improved the wetting property between NCC and polyurethane significantly. The modified NCC was characterized by X-ray powder diffraction (XRD). And the wetting property was indicated by contact angle (CA). Epoxy groups from 6% GPTMS led to a 47.6% decline of CA, while the improvement of wetting property from APTES was inconspicuous.

Abstract: UV-visible spectroscopy and fluorescence quenching measurements have been employed to study electron transfer from excited Hypocrellin A (HA) into the conduction band of a colloidal ZnO semiconductor. The adsorption of HA on the surface of ZnO colloidal particles and the electron transfer process from its singlet excited state to the conduction band of colloidal ZnO semiconductor were examined under experimental conditions. Exciting HA with visible light could induce electron transfer from its singlet excited state into conduction band of colloidal ZnO semiconductor. Adsorption of HA onto the surface of colloidal ZnO semiconductor extended its absorption spectrum further into the visible region, the quenching behavior were observed as the colloidal ZnO semiconductor was added and determined by fluorescence quenching method.

Abstract: Before hot rolling the ingot of plain carbon steel Q235 should be heated to austenite temperature to decrease distortion resistance. The grain size will affect the following hot rolling process. In this paper, the behaviour of Q235 grain growth in reheat furnace was studied with the method of physical simulation. To achieve the equation of grain growth in heating progress, the samples was carried out in different peak temperature and holding time at the Gleeble1500. With the kinetics equation grain size can be calculated and the results provide a basis for the setting of progress parameter during reheating of ingot.

Abstract: Using polymer as a surfactant, we successfully synthesized of PbTiO3 crystals with a self-assembly structure by a hydrothermal process. The as-obtained powders were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The results show that the presence of PVP, PEG and PVA plays a key role on the formation of self-assembly structure and the corresponding formation mechanism was briefly discussed.

Abstract: The liquid eutectic system comprising 1:1 menthol:camphor was selected to use as solvent due to it was lowest viscosity. Both menthol and camphor used in this eutectic system have been reported for their many pharmaceutical used. Various polymers were tested for their solubility in this eutectic system. Eudragit® EPO showed the highest solubility. Eudragit® EPO was the one of biocompatible polymer which could dissolve in this eutectic system up to 40% w/w with no chemical interaction of each compound. Viscosity of this system showed the exponential curve as a function of polymer concentration but all concentration showed the newtonian rheology. The pH and surface tension were slightly affected by type and amount of polymers. The obtained polymeric eutectic mixture should control the drug release for pharmaceutical applications.