Advanced Materials Research Vols. 1044-1045

Abstract: The nanosized water-soluble Oa-POSS particles were added into the PNIPA hydrogels by in situ radical polymerization as a reinforce agent. The mechanical properties are determined by the composition of gels. With the increase of Oa-POSS, the tensile and compression strength is enhanced significantly, while, the elongation at break is still low. The increased BIS, related to the tighter network structure, results in better compression strength, but the tensile properties is not improved obviously.

Abstract: A novel POSS hybrid nanocomposite hydrogels was synthesized by introducing water-soluble Oa-POSS into the PVA hydrogels by freeze-draw mode. The freezing temperature and freeze-thaw cycle times affected the mechanical properties of gels. When polymerizing at lower temperature, the tensile strength and modulus increases and the elongation at break decreases obviously. Meantime, with the increase of freeze-thaw cycle times, the strength, modulus and elongation at break all improved gradually.

Abstract: NaYF4 microcrystals were synthesized using a hydrothermal method, and the effects of the EDTA and NaF addition amount on the crystal structure, morphology and size were systematically studied. When the NaF addition amount increase, the size of the NaYF4 microcrystal increase, the excess F- ions promote the formation of β-phase of NaYF4. EDTA significantly modifies the morphology of the crystals. When addition the EDTA the crystals transition from irregular silkworm-like microcrystal to hexagonal microprisms. And the EDTA also promote the hexagonal phase formation.

Abstract: The nanosized water-soluble Oa-POSS particles were added into the PDMAEMA hydrogels by in situ radical polymerization. The gels still show obvious temperature and pH double responsiveness. The swelling behavior including swelling ratio and swelling/deswelling rate is determined by the content of added Oa-POSS. With the increase of Oa-POSS, the swelling ratio decreases slightly, while the swelling rate and deswelling rate increases significantly, which is conducive to the application of this kind of gels.

Abstract: In the present study, the effect of N, Ta and Co addition to near-α Ti-Al-Sn-Zr based alloy, on mechanical properties and microstructure has been investigated. Mechanical properties were investigated based on compression test at room temperature and at 650°C. Microstructure was investigated using optical microscope and scanning electron microscope. The results showed that addition of N, Ta and Co improved room temperature compressive strength. The strength improvement is mainly due to precipitation hardening mechanisms. At 650°C, only N addition improved compressive strength. The results were discussed based on the microstructure observation.

Abstract: The aim of this work is to study the behaviour of two types of composite material when subjected to impacts at different energy levels under low velocity impact events. The composite material used in this study was Glass Fibre Reinforced Polymer (GFRP) which was C-type/600 g/m² and E-type/600 g/m². This material was fabricated to produce laminated plate specimens with a dimension of 100 mm 150 mm. Each specimen had 10 layers of GFRP woven roving plies. The low velocity impact test was performed using an IM10 Drop Weight Impact Tester with a 10 mm hemispherical striker cap. The impact energy was set to 14, 28, 42 and 56 joules with velocity ranging from 1.73 m/s to 3.52 m/s. The relationships of impact energy with impact force, displacement and energy absorbed are presented. The comparison and behaviour between the two types of GFRP are discussed.

Abstract: A series of bipolar materials for thermally activated delayed fluorescence (TADF) based on carbazole and diphenylsulfone, is synthesized by Ulmann and Suzuki coupling reactions. In these materials, the 3,6-di-tert-butylcarbazole and N-phenylcarbazole group as donors are linked at the 3-, 4-position of diphenyl sulfone. The electronic, photophysical and electrochemical properties of these materials are studied by extensive UV-vis, fluorescence spectroscopic measurements, cyclic voltammetry as well as theoretical calculations. The energy gap between singlet and triplet (△E_ST) in these materials is tuned from 0.99 eV to 0.24 eV by changing the donor units and the positions of substitution.

Abstract: Casting Mg-Li alloy samples were subjected to annealing and aging treatment respectively, and the corrosion resistance of different samples was investigated by immersion test and electrochemical impedance spectroscopy measurement in 3.5% NaCl solution. The results show that the corrosion resistance of the as-cast sample is the best,the aged sample is the second, and the annealed sample is the worst to resist corrosion.

Abstract: Hierarchically structured LDHs are being actively investigated due to their potential applications in bioseparation and catalysis which result from their special surface structures and positively charged nanosheets. This work presents an effective method of fabricating hierarchical LDHs based materials with high surface-to-volume ratios. To do this, the microscaled Al₂O₃ fibers are fabricated via a simple biotemplate method employing paper fibers as templates and in the second step the nanoscaled Ni-Al LDH platelets are fabricated into hierarchical architectures based on crystal growth on surface of Al₂O₃ fibers. In order to obtain the multi-component and multi-scale structure LDHs based materials, the ZnO/LDHs composites are obtained by controlling crystal growth process. The developed facile route is highly valuable and feasible for hierarchical porous LDHs based materials for applications in research and industrial fields.

Abstract: Metal oxide semiconductors materials such as zinc oxide (ZnO) are often used in the fabrication of chemoresistive gas sensors, but ZnO materials require high operating temperatures to operate. In another side, carbon nanotubes (CNT) have many distinct properties and recently have been exploited as the next generation of sensors, including chemoresisitive type gas sensors. This study was aimed to investigate the performance of MWNT-ZnO composites as SO₂ gas sensitive layer. By fabricate composites of MWNT and ZnO, have been obtained a sensitive layer that can be utilized for application as gas sensitive layer with relatively lower operating temperature. A sensitive layer of MWNT-ZnO based composites have been successfully fabricated on a alumina substrate and several characterization techniques has been performed, i.e. XRD, SEM and EDS to study the formed crystalline phase, the morphology of the nanostructures, and the elemental composition of synthesized composites. MWNT-ZnO sensitive layer was tested by exposure to SO₂ gas at various operating temperatures and gas concentration. From the performance testing results, it could be found that the composite materials have a prospective as a gas sensor at lower operating temperature with short response time and good sensitivity.