Advanced Materials Research Vol. 658

Abstract: Single-walled carbon nanotubes were dispersed in deionized water with sodium dodecyl benzene sulfonate as surfactant. The solutions were sprayed on UV and plasma treated polyethylene terephthalate to achieve transparent conductive films with excellent adhesion. The carbon nanotube films were further treated with different concentrations of nitric acid to improve conductivity. SWCNTs and films were characterized by thermo gravimetric analysis, field-emitting scanning electron microscopy, UV-VIS spectrophotometer, four-point probe method, and Raman spectroscopy. The results demonstrated that the conductivity of carbon nanotube films with high transparency was improved to a greater degree with higher concentration of nitric acid due to effectively removing residual surfactants. The low sheet resistance films of ~100 Ω/sq @ 80T% have widely applications in touch screen, flat panel displays, organic light emitting diode, and etc.

Abstract: A twin-screw extruder was used to carry out the ring opening graft polymerization of L-lactide onto cellulose through reactive extrusion process. Ionic liquid (1-butyl-3-methylimidazolium chloride) [Bmim]Cl and Sn(oct)2 were used as solvent and catalyst, respectively. FTIR, TGA and XRD were used to investigate the structure, thermal stability and crystalline behavior of the reaction products. The result showed a successful ring opening polymerization of L-lactide on cellulose. Furthermore, it showed a increased crystalline degree and thermal stability after being introduced the PLLA.

Abstract: Nanoscale Fe/Ni alloy particles have been synthesized by hydrothermal method in this study. The influences of various reaction temperatures on the properties and morphologies were studied. The structure of Fe/Ni alloy nanoparticles were characterized by SEM, XRD and FTIR. Additional, the magnetic and electrical properties were also studied to obtain the optimum reaction condition. It would provide the foundation to the study about the synthesis and performance of iron-based nanoscale alloy powder.

Abstract: Polylactide (PLA) was plasticized by two types of plasticizers, glycerol and triacetin. These plasticized PLA were mixed with carboxymethylcellulose (CMC). It was found that with only small amount of CMC, 4.5 wt%, it is effectively to lower glass transition, cold crystallization and melting temperatures of glycerol-plasticized PLA (PLA-g) but not much affected on tensile properties. Moreover, increasing amount of CMC twice could not much affect thermal properties but largely reduced tensile strength, modulus and elongation. The melt flow index of the PLA-g increased largely with the amount of CMC. When 4.5 wt% CMC was added to the glycerol-triacetin plasticized PLA, only glass transition temperature became lower than that of 4.5 wt% CMC filled PLA-g but melting temperature and crystallinity were rather increased with poorer mechanical properties. Increasing amount of CMC tended to enhance melting temperature but still rather poor mechanical properties and high melt flow index. So, the CMC had strong positive effect on melt and negative effect on solid properties of plasticized PLA.

Abstract: Four natural dyes from sappan wood, noni leaves, safflower and black rice show 4 different colors, red, green, yellow and dark purple. They were extracted by water/ethanol and used as a sensitizer for the ZnO based dye-sensitized solar cell (DSSC). UV-Visible absorption revealed high extinction coefficients of the safflower, noni leaves and sappan wood while the black rice was opposite. And they were adsorbed on ZnO nanoparticles as suggested by the change in absorption spectrum of ZnO. SEM results showed the ZnO nanoparticle-porous film of 9 micron thick. I-V measurement showed both low short circuit current and open circuit voltage leading to poor fill factor. As a result, the efficiencies of the fabricated solar cells were 0.00165, 0.05865, 0.00007 and 0.00015% for sappan wood, noni leaves, safflower and black rice DSSCs, respectively.

Abstract: In the present study, the anti-inflammatory effects of tetrandrine-loading poly (L-lactic acid) (PLLA) films were investigated in vitro. The surface characteristics of blank PLLA film and tetrandrine-loading PLLA films were examined by electron spectroscopy for chemical analysis (ESCA). The ESCA data suggested that the tetrandrine-loading PLLA films became enriched with nitrogen atoms. The MTT assay was applied to evaluate the cytotoxicity of PLLA films with RAW264.7 cells. Production of nitric oxide (NO) was measured by the Griess colorimetric method. The gene expression levels of inducible nitric oxide synthase (iNOS) and IL-6 were detected by quantitative real-time reverse-transcription polymerase chain reaction (real-time RT-PCR). These results suggested that the anti-inflammatory effects of tetrandrine-loading PLLA films might be the results from modulating the NO/iNOS pathway and inhibiting the mRNA expression of iNOS and IL-6 in activated macrophages.

Abstract: This experimental study investigates the flexural behavior and toughness of sprayable strain-hardening cement composite (SHCC) developed to retrofit seismically reinforced concrete structures with non-ductile reinforcement details. Three SHCC mixtures with specified compressive strength of 50 MPa are mixed and tested. All SHCC mixes with different dosage and combination of admixtures such as superplasticizer and powder admixture were reinforced with 2.2 % polyvinyl alcohol (PVA) fibers at the volume fraction. This paper focuses on the flexural toughness based on the flexural test results for 100 x 100 x 400 mm prisms. The flexural toughness is evaluated in accordance with ASTM C 1018. The results indicated that less than 2.5 % dosage of hybrid superplasticizer and powder admixtures respectively provides excellent sprayability and flexural behavior of SHCC mixed in this study. A strong influence of hybrid superplasticizer and powder admixture on the flexural toughness of SHCC mixes was observed.

Abstract: This paper summarizes the experimental results of concrete sandwich wall panels (CSWP)specimens under pull-out loading conducted to investigate the effect of insulation type and reinforcing area of shear connector made with glass fiber-reinforced polymer (GFRP) on the shear behavior of CSWP used as exterior cladding walls.In this study, two types of thermal insulations;expanded polystyrene(EPS)and extruded polystyrene with special slots(XPSS) and wave-shaped GFRP shear connectors with different reinforcing area; 6mm x 2mm and 12mm x 2mm were used for CSWP specimens.Test results indicated that the types of insulations and reinforcing area of GFRP shear connectors have a significant effect on the direct shear behavior between concrete wall and insulation. As reinforcing area of GFRP shear connector increase, increase in shear strength of CSWP with EPS insulation is less than CSWP specimens with XPSS insulation due to relatively lower strength of EPS compared to XPSS strength.

Abstract: This study was conducted to experimentally investigate the shear behavior of non-ductile squat shear walls with different cement matrixes such as normal concrete, fiber-reinforced concrete(FRC), and strain-hardening cement composite(SHCC). The cement matrix type’s effect in the lightly reinforced squat shear wall was evaluated through the testing of three one-third scale walls with a height-to-length ratio (hw/lw) of 0.55 under top displacement reversals. Experimental results show that the cement matrix type in the non-seismically detailed squat shear walls has a significant effect on the shear behavior and failure mode. Compared to reinforced FRC and SHCC shear walls, reinforced concrete wall exhibited brittle behavior. Reinforcing fibers in the FRC and SHCC mitigated the crack damage of wall and increase the shear strength.