Advanced Materials Research Vols. 93-94

Abstract: The aim of this work is to fabricate an ethylene gas sensor based on polyaniline (PANi). The conductive layer of emeraldine base PANi was prepared by electrochemical synthesis. The aqueous aniline solution in sulfuric acid was electrolyzed by repeating potential cycling between -0.4 and 1.0 V relative to the silver reference electrode and platinum counter electrode. The conductive layers of PANi were deposited on patterned interdigited gold substrate. The numbers of repeated potential cycles on the amount of deposited layers of PANi were investigated for ethylene gas detection. The morphology of PANi films was investigated by scanning electron microscope (SEM). The ethylene gas sensing of PANi-H2SO4 was evaluated based on the changes in conductivity of PANi-H2SO4. The results revealed that the magnitude sensing provided a good sensitivity against ethylene with concentration in the parts per million (ppm) ranges. The effect of amount of deposited layer of PANi on ethylene gas sensing will be presented.

Abstract: Recently, red seaweed attacks growing interests as 3rd generation biomass due to their notable characteristics e. g. no lignin, high CO2 fixation ability as well as high carbohydrate contents such as galactan and glucan. Seaweed may belong to one of the several groups of multicellular macro algae (the red algae, green algae, and brown algae). The ecology of seaweeds is dominated by two specific environmental requirements, that is the presence of seawater and light sufficient to drive photosynthesis. Seaweed is currently being researched as a potential source of biofuel in the form of bioehtanol. Especially, Gelidium amansii known as one of the red seaweed can be depolymerized to produce mixed monosugars such as glucose and galactose. We describe here the polysaccharide extract conditions using G. amansii to maximize the total yields of polymers and their conversion rate into monosugars which are able to be converted into bioethanol.

Abstract: The aim of this study was to improve the enteric properties of shellac by composite salt formation with ammonium hydroxide (AMN) and 2-amino-2-methyl-1,3-propanediol (AMD). The shellac films were prepared by dissolving shellac with various combination of AMD:AMN and then characterized for physicochemical and mechanical properties. The results indicated that the solubility of shellac films was increased as increasing proportion of AMD. The percentage of dissolved film at pH 7.0 of 100:0 AMD:AMN (100%AMD) was approximately 3 times higher than that of 0:100 AMD:AMN (100% AMN) while the percentage of dissolved film at pH 1.2 was slightly increased as increasing proportion of AMD. These results suggested the solubility at intestinal pH was improved while the gastric protection was still in the acceptance level. The FTIR spectroscopy of all composite salts demonstrated the peaks at 1716 and 1556 cm-1, which were attributed to the carbonyl stretching of carboxyl and carboxylate groups, respectively. The absorbance ratio of FTIR peaks (ABS1556/ABS1716) was increased with the higher proportion of AMD, suggesting that the solubility enhancement was due to higher ionization degree of AMD salts. The mechanical properties of films were also changed after salt formation. As increasing the AMD:AMN ratio, the percent elongation of films has increased. The result suggested for more flexibility of films. In conclusion, the improved enteric properties of shellac films were achieved after composite salt formation with AMD.

Abstract: SrTiO3 is one of the most technologically important dielectric ceramics. In this paper, SrTiO3 nanoparticles were synthesized by a simple sol-gel route using NaOH to adjust the pH of the system. Three different strontium-containing starting precursors (Sr(NO3, SrCl2.6H2O and Sr(CH3COO)2.0.5H2O) were employed. Thermogravimetric analysis (TGA) showed complete decomposition of organics at approximately 800°C; this temperature was chosen as a calcination temperature. At 800°C, 6 hours, only the nitrate route with pH = 10 gives single-phase SrTiO3. Other conditions yield various impurities, most likely due to the incompletion of the reaction although they still contain very broad XRD peaks corresponding to SrTiO3, signifying the probable phase formation capability at these conditions. The obtained SrTiO3 powders are in the nanoscale range of 10 to 40 nm with isotropic morphology.

Abstract: In this work, the effect of ethylene vinyl acetate (EVA) on the rheological and mechanical properties of low-density polyethylene (LDPE)-based greenhouse plastic films was explored. The rheological experiments showed that, for given PE and EVA, both complex viscosity and storage moduli of LDPE/EVA blends were not significantly affected when EVA content is less than 30%wt but increased with increasing EVA content thereafter. However, the mechanical results inconsistently showed that blown films with 10%wt EVA content gave the most superior mechanical properties compared to other blends. It was found that, at higher EVA contents, immiscibility between the LDPE and EVA phases occurred, resulting in much poorer mechanical performance.

Abstract: Periodontal disease is a major cause of tooth loss, therefore a more recent approach such as thermosensitive gel is loaded with antimicrobial drugs to be delivered locally to the periodontal pocket. The effect of ZnO on thermosensitive gel properties including gelation-gel melting temperature, rheology, syringeability, and the release behavior of antimicrobial drug such as doxycycline hyclate were investigated. The increased amount of ZnO apparently decreased the gelation temperature of the Lutrol® F127 system. Syringeability of the doxycycline hyclate-Lutrol® F127 systems were increased with the increased amount of ZnO. System comprising zinc oxide could prolong the release of doxycycline hyclate from Lutrol F127 systems and could be delivered from a syringe through a needle for utilizing in periodontitis therapy at the periodontal pocket.

Abstract: Certain applications of functionalised and sensing material require network of connectors such as conducting nano-wires, to pick displaced electrons or signals from an external source. Making nano-scale networks of connections that are durable, efficient and continuous is always a challenge for the material scientists. A possibility to achieve the above goals by mimicking dendritic and other diffusion patterns in nature is discussed here. These ‘naturally grown’ textures have the following characteristics that are very useful, as their intrinsic properties: 1. two branches will never overlap (saving material and avoiding any short circuiting), 2. all the branches will always have in contact with the root. Further, when it is practically impossible to develop a network of branches in an already existing solid material, induced dendritic growth using controlled diffusion can be used to do the job.

Abstract: Nanocomposite polymer electrolytes were prepared by incorporating different amounts of zirconium oxide (ZrO2) nanofiller to poly(vinylidene fluoride-co-hexafluoropropylene)-lithium trifluoromethane sulfonate (PVDF-HFP-LiCF3SO3). X-ray diffraction (XRD) study has been carried out to investigate the structural features of the electrolyte films while a.c. impedance spectroscopy has been performed to investigate their electrical properties. The conductivity of nanocomposite polymer electrolyte systems is influenced by nanofiller concentration. The increase in conductivity is attributable to the increase in the fraction of amorphous region and the number of charge carriers and vice versa. The highest conductivity obtained is in the order of 10-3 S cm-1 for the system dispersed with 5 wt% of ZrO2 nanofiller.

Abstract: Local structures of indium oxynitride (InON) nano-crystal prepared by reactive gas-timing RF magnetron sputtering technique are under investigation. Since the optical properties of these InON thin films depend on gas-timing ratio, the local structure analysis is needed in order to determine the relation between the gas timing ratio and its optical properties. In this work, InON thinfilm with 30:0 seconds (N2:O2) gas-timings ratio was analyzed for its local structure using X-ray absorption fine structure (XAFS) technique in conjunction with first principle calculation. The results indicate that the crystal structure of the film is wurtzite structure which is a typical structure of InN. However from the results of Auger Electron Spectroscopy (AES), there are oxygen contents in the film. Since XAFS analysis confirmed the 4-fold local structure of Indium atom, these oxygen atoms must be substituted in nitrogen sites with slightly changing the local structure of Indium atom. The best fit of XAFS data indicated that there is an oxygen atom substituted in nitrogen site of the 4-fold indium.

Abstract: An experimental was investigated the condition of reinforcement of epoxy resin and hemp fiber/epoxy resin composites with carbon nanotubes (CNTs). The CNTs adding nanopowder were vibrated via the vibration milling technique for 6-48 h. Different volume percentages of CNTs were dispersed for hemp/epoxy resin composites. To compare properties of composites sample, CNTs were also added into epoxy resin for reference. Tensile strength of both specimens was tested. The significantly adding of CNTs and its dispersion in polymer matrix were investigated by scanning electron microscope (SEM). The results indicate that adding the milled CNTs can improve tensile properties of composites.