Advanced Materials Research Vols. 93-94

Abstract: The ionic materials were added to PEDOT/PSS solution as secondary dopants. The conductivity of PEDOT/PSS film improved with adding ionic materials. The film of PEDOT/PSS with 1% pyridinium p-toluene-sulfonate showed the conductivity of 23S/cm, which is increased about three orders than the film of origin PEDOT/PSS with 0.028S/cm. The surface morphology of films of PEDOT/PSS mixture is investigated by atomic force microscope. The AFM showed the increasing of grain size with the addition of pyridinium p-toluene-sulfonate.

Abstract: Degradation of LDPE and PP films using the photo sensitive metal oxides or pro-oxidants (e.g. Fe2O3, CuxO, ZnO, and TiO2 at various particle sizes) as the catalysts in both thermo- and photo-oxidation of plastic films with oxygen followed by photolytic process to give free radicals has been studied. Our preliminary study in hexane solution found that the carbonyl index (CI) increased under the shortwave ultraviolet (254nm) significantly greater than under the longer wave (366nm) due to its greater energy and highly absorbed by the pro-oxidants generating more free radical concentration which could then be photolysed into carbonyl compounds. The pro-oxidant blended PE and PP films under ultraviolet (254nm) irradiation showed the carbonyl index elevation at the beginning and then reducing to a constant level similarly in most cases. This probably suggested that the carbonyl primarily formed and degraded into other free radicals. Under shortwave ultraviolet irradiation for 72 hours, the LDPE films containing nano-sized rutile-TiO2 and nano-sized anatase-TiO2 (1%w/w) were able to reduce the film tensile strength by 32% and 55%, respectively. The film containing micron-sized commercial TiO2 lower the film tensile strength only by 7-10%. However, the tensile strength of the TiO2 blended PP films tends to increase possibly because the rate of cross linkage exceeds the rate of scission.

Abstract: Properties of La2-xSrxMo2-yWyO9-δ (x = 0-0.2, y = 0-0.3) synthesized via citrate gel method have been investigated on phase, oxidation state, microstructure and electrical conductivity. The XRD results show a single phase after calcination at 700 oC for all compositions. The oxidation state of Mo in La2-xSrxMo2-yWyO9-δ compositions determined by X-ray Absorption Near Edge Structure (XANES) is found to be +6. The average grain size of sintered compositions increases with the amount of Sr but slightly decreases with an addition of W. At 500 oC, all doped compositions exhibit higher conductivity as compared to 5.42×10-4 S∙cm-1 for undoped-La2Mo2O9. In this work, the composition of La1.9Sr0.1Mo2O9-δ performs the highest conductivity value of 1.95×10-3 S∙cm-1.

Abstract: Na- β"-alumina solid electrolyte proposed for electric vehicle battery system application was prepared using liquid phase sintering method. Firstly, the Na- β"-alumina powder was prepared according to the formular Na1-xMg2xAl5-xO8 with x = 0.175, calcinations temperature was at 1200 C for 10 h. Calcined powder was milled and mixed with Bi2O3 or CuO in approximate concentration 1, 3 and 5 percent by mole respectively. The uniaxial dry-pressing was employed for green body forming. The green pellets were then sintered at different temperature and dwell time were kept constant for 4 h during the sintering process. Ionic conductivity measurement was performed by impedance analyzer. The XRD characterization on both powder and ceramic show that β"-alumina form as a major phase with tiny amount of the secondary phase β-alumina. The β"/β concentration proportion slightly decrease after sintering. Addition with Bi2O3 or CuO do not lead to phase change and high densification ceramic is obtained. Ionic conductivity of β"-alumina ceramic added with Bi2O3 is higher than that of ceramic with CuO addition. The relative calculated activation energy of the Na+ migration in the former composition is also lower. The highest ionic conductivity measured at 300 C is found in ceramic sample sintered at 1450 C and with 1 mol% of Bi2O3.

Abstract: Titanium oxide TiOx material is used as electron transporter in organic photovoltaic cells (OPV). The layer was prepared between P3HT:PCBM as the active layer and the and aluminum electrode by spin coating technique. The synthesis and characterization of TiOx is described. Using Raman spectroscopy technique TiOx crystals show anatase structure. Varied concentrations of TiOx and isopropanol solvent were performed. The most optimized device efficiencies up to 2,0% was achieved at a 1:20 ratio, which indicated more than 50% efficiency enhancement comparing with the device without TiOx layer. The major improvement of the cell was originated from photocurrent enhancement.

Abstract: In this work, the yellow emitted perylene-bisimide dye with polymerizable functional groups was synthesized by condensation reaction of perylene tetracarboxylic acid dianhydride and allyl amine. The resulting polymerizable fluorophore was characterized in terms of structure with NMR and FT-IR, the absorption and emission properties by using UV-Vis and fluorescence spectroscopy, respectively. Afterwards, the reactive polymerizable fluorophore was incorporated into the polymer nanoparticle by copolymerization with styrene and acrylic acid monomers via miniemulsion polymerization. The obtained fluorescent nanoparticles was stable and showed a highly monodisperse size distribution with hydrodynamic diameter of 91.8±0.4 nm.

Abstract: In situ silica filling of styrene grafted natural rubber (ST-g-NR) was carried out by using sol-gel reaction of tetraethoxysilane (TEOS). The effects of concentration of catalyst and reaction temperature on the in situ silica content were investigated. ST-g-NR was synthesized via an emulsion polymerization using cumene hydroperoxide (CHPO) and tetraethylene pentamine (TEPA) as initiators. The synthesized ST-g-NR was characterized by a Fourier Transform Infrared Spectroscopy (FTIR) and Proton Nuclear Magnetic Resonance Spectroscopy (1H NMR). The content of in situ silica generated in ST-g-NR matrix was determined by Thermogravimetry Analysis (TGA). In situ silica up to 50 parts per hundred rubbers by weight (phr) was successfully filled in the ST-g-NR matrix. The silica content increased with the increase of n-hexylamine concentration. However, the effect of reaction temperature was insignificant to silica content.

Abstract: The aim of the present study was to investigate the organic and inorganic compositions of enamel and dentine after Er:YAG laser irradiation using Fourier-transform Raman spectroscopy (FT-Raman). The enamel and dentine of extracted human teeth were irradiated by Er:YAG laser at an energy density of 29.7 J/cm2. The organic and inorganic components were evaluated from Raman spectra of untreated and laser-treated of extracted human teeth. The results showed that the Raman intensity ratio of the carbonate peak (1067 cm-1) to the phosphate peak (957 cm-1) and the organic peak (2940 cm-1) to the phosphate peak of enamel and dentine decreased after laser irradiation. Therefore, laser treatment can reduce the organic and inorganic components of human enamel and dentine.

Abstract: Copper Phthalocyanine (CuPc) thin films have a potential to use as nitrogen dioxide (NO2) gas sensor therefore the study of property modification of CuPc thin film by NO2 gas can lead to a better understanding the sensor operation. CuPc thin films were prepared by thermal vacuum deposition on glass substrate and aluminum interdigitated electrodes. The film characteristics were investigated with and without NO2 gas. These characteristics indicated that the resistance of CuPc film decrease as the NO2 concentration increases. In order to achieve high efficient of sensing properties, the post-deposition film was also annealed. The surface modifications were investigated with different exposed time of NO2 gas. Their properties modifications before and after annealing were investigated on the film morphology and crystalline structure. The surface morphology of the film was examined by atomic force microscopy while the crystalline structure of the film was determined by x-ray diffraction. The electrical measurements of CuPc film exposed to NO2 gas were studied in order to investigate property modification of the CuPc film.

Abstract: The fabrication and characterizations of nanocrystal-ZnO thin film used as active layer of MSM-photodetector structure are reported. The ZnO thin film were successfully sputtered on SiO2/Si substrates without heating or annealing processes by using a novel reactive gas-timing technique. In our experiment, the ZnO thin film properties with different gas-timing ratio of Ar/O2 were investigated. For fabricating of UV detector, the Al interdigitate electrode was deposited on SiO2/Si substrate by DC sputtering process and ZnO thin film was deposited as active layer. The response wavelength peak occurs at around 380 nm corresponding to ZnO energy bandgap of 3.2 eV .The I-V measurements indicates the Schottky behavior of ZnO on Al contact.