Advanced Materials Research Vol. 832

Abstract: A preliminary investigation of polymer electrolyte based on hexanoyl chitosan, lithium perchlorate (LiClO₄) and various filler additives are described in this paper. Hexanoyl chitosan-based nanocomposite polymer electrolytes were prepared using solution casting technique. The effect of filler addition and type of filler on the electrical properties of the prepared electrolyte system was investigated by impedance spectroscopy (IS). The maximum conductivity of 3.06 × 10^-4 S cm^-1 and 1.96 × 10^-4 S cm^-1 were achieved for the hexanoyl chitosan-LiClO₄-TiO₂ and hexanoyl chitosan-LiClO₄-SiO₂ electrolyte system, respectively. The variations in conductivity observed were discussed quantitatively using the Rice and Roth model from which the concentration of free ions and their mobility were calculated.

Abstract: Hexanoyl chitosan exhibited solubility in tetrahydrofuran (THF) was prepared by acyl modification of chitosan. Polystyrene with molecular weight 280,000 g mol^-1 was chosen to blend with hexanoyl chitosan. LiCF₃SO₃ was employed as the doping salt. Untreated and H₂SO₄ treated TiO₂ was added as the filler. Films of hexanoyl chitosan-polystyrene-LiCF₃SO₃-TiO₂ polymer electrolyte were obtained by solution casting technique. The ac conductivity of the sample was calculated from the relation σ_ac = ε_oε_iω, where ε_o is the permittivity of the free space, the angular frequency, ω=2πf, and ε_i is the dielectric loss. The ac conductivity dispersion observed is analyzed using the Jonshers universal power law, σ (ω) = σ_dc + Aωⁿ where A is a pre-exponential constant and n is the power law exponent with value in the range 0 < n < 1. The temperature dependence of exponent n will then be interpreted using the existing theoretical models.

Abstract: Recently, energy saving glass is commonly applied in the modern engineered building. This is due to its advantages of keeping the heat inside the building in winter while rejecting the heat when in summer. The typical energy saving glass is made by applying a very thin metallic oxide such as silver oxide or tin oxide on one side of the float glass. But at the same time, it has the disadvantages of attenuates useful microwave frequencies that ranging from 0.8 2.2 GHz. The examples of the microwave frequency at this range are GSM mobile signal, GPS and personal communication. Frequency selective surface (FSS) has been introduced to overcome this drawback of energy saving glass. In this study, the transmission of the microwave signal is observed through the simulation using Computer Simulation Technology Microwave Studio. Bandpass frequency selective surface of cross dipole shape is used for the simulation. In the simulation, conductivity and electrical properties of glass and metal oxide thin film are important. The microwave transmission was evaluated at various sheet resistance of metal oxide thin film. The results show that the minimum transmission lost increased with the ohmic resistance increased. On the other hand, the peak frequency at various sheet resistance shows constant value at around 1.25-1.30 GHz. The full width half maximum of the microwave transmission increases with the sheet resistance value. The results suggest that FSS structured metal oxide thin film with lowest sheet resistance transmits more signal in the range for GSM phone signal.

Abstract: Growing carbon nanotubes (CNT) on the surface of high performance carbon fibers (CF) offers a means to tailor the mechanical properties of the fiber-matrix interface of a composite. In the context of this work, a floating catalyst chemical vapor deposition (CVD) unit was utilized to grow CNT onto the surface of CF. The surface and mechanical properties of the resultant fibers, CNT density and alignment morphology were explained to depend on the CNT growth temperature, growth time, and atmospheric conditions within the CVD chamber. Single fiber/Epoxy composite coupons were fabricated by using both neat and CNT-coated CF to conduct single fiber fragmentation test (SFFT). It was observed that the coating of CNT onto CF surface improves the IFSS between CF and matrix when compared with neat-CF. Particularly, CF treatment condition for CNT-coating with 700 °C reaction temperature and 30 minutes reaction time has shown a considerable increase in IFSS approximately of 45% over that of the untreated fiber from which it was processed. The fiber-matrix adhesion was analyzed by using SEM on cryogenically fractured surface of both types of composites. The proper justification of fiber-matrix adhesion featured by composite interfacial properties was explained through IFSS.

Abstract: Copper oxide is a low cost material, easy process fabrication and sensitivity to ambient conditions. Therefore, it is a suitable p-type semiconductor oxides material to be used as a gas sensing material. In order to raise the sensitivity of the copper oxide gas sensor, study on the correspondence in between the coated thin film with coating parameters is an important part. In current study, optical emission spectroscopy is used to investigate the reactive magnetron sputtering plasma during the deposition of copper oxide thin film. The measurement point was focused at roughly 2cm above the substrate holder. The emission of copper, oxygen and argon in the reactive magnetron sputtering were observed at various plasma conditions. In general, the emission of copper, oxygen and argon increased when the discharge rf power is increased. On the other hand, oxygen line intensity was found to be excess when the oxygen flow rate is above 8sccm. The result suggests the best condition to deposit the copper oxide thin film using solid 3 copper target.

Abstract: Nanoemulsions are a class of nanomaterials which play an increasingly important role in commercial and environmental aspects. Water-in-diesel (W/D) nanoemulsion is considered one of the environmental friendly alternative fuels for reducing the emission pollution of internal combustion engine such as diesel engines. In this context, a study has been made to evaluate the combustion characteristics of W/D nanoemulsion fuel. A wide range of surfactant concentration (0.25% to 0.40% v/v) with varying amount of water percentage (0.5% to 0.8% v/v) was used in the preparation of W/D nanoemulsion fuel. The high energy emulsification method was applied to prepare W/D nanoemulsions. The combustion characteristics of W/D nanoemulsions are presented in terms of different formulating compositions. An engine test bed was used to combust the W/D nanoemulsions for measuring the exhaust emission concentrations such as CO, CO₂ and NH₃. A reduction in the concentrations of exhaust gas emissions was notified.

Abstract: Plate heat exchanger with chevron angle has higher heat transfer area than flat type and increases the level of turbulent due to its corrugated channel. In this study, both water and nanofluid were used to determine the heat transfer coefficient and rate, pumping power, and pressure drop. A commercial plate heat exchanger with two different symmetric (30⁰/30⁰_, 60⁰/60⁰) and one mixed (30⁰/60⁰) chevron angle plates were considered for analysis. Al₂O₃ and SiO₂ nanoparticles with 0-1 vol. % concentration were used with water. From the analysis it was found that, convective heat transfer coefficient, heat transfer rate, pressure drop and pumping power increases with the increase of volume concentration. Moreover, the above parameters were found to be higher for 60⁰/60⁰ chevron angle plates. A correlation of Nusselt number as a function of Reynolds number and Prandtl number for different chevron angles needs to be obtained based on experimental and analytical work. Nomenclature

Abstract: This paper presents an overview of research works on the utilizing of soft computing in the optimization of process parameters and in the prediction of thin film properties in sputtering processes. The papers from this review were obtained from relevant databases and from various scientific journals. The papers collected were published from 2008 to 2012. The focus of the review is to provide an outlook on the utilization of soft computing techniques in sputtering processes. Based on the review, the soft computing techniques which have been applied so far are ANN, GA and Fuzzy Logic. The first finding of this review is that soft computing technique is a promising and more reliable approach to optimize and predict process parameters compared to the traditional methods. The second finding is that the utilizing of soft computing techniques in sputtering processes are still limited and still in exploratory phase as they have not yet been extensively and stably applied. The techniques applied are also limited to ANN, GA and Fuzzy, whereas the exploration into other techniques is also necessary to be conducted in order to seek the most reliable technique and so as to expand the application of soft computing approach. Future research could focus on the exploration of other soft computing techniques for optimization in order to find the best optimization techniques based on the specific processes.

Abstract: An approach in the prediction of zinc oxide (ZnO) thin films properties based on neural network is presented in this paper. The research had been focused on the electrical properties of ZnO. The sputtering power, substrate temperature, deposition time and oxygen ratio were selected as the input variables while the resistivity and conductivity were selected as the output. The numerical results obtained through the neural network model were compared with the experimental results. The result obtained from the system model of the proposed procedure was reasonably good and promising. Therefore, the prediction based on neural network model is a reliable approach compared to the traditional method of trial-and-error process.

Abstract: We report on the influence of the low deposition temperature of ZnO as semiconductor layer on the electrical characteristics of metal-insulator-semiconductor (MIS) structures. The ZnO films were deposited by radio frequency (RF) magnetron sputtering with variation of temperature from 40°C, 60°C, 80°C, 100°C and 120°C. PMMA were used as insulator layer in the MIS structures. It is found that the ZnO films grown at 120°C has better crystallinity compared to other temperature. I-V characteristics results shown that the different deposition temperature of ZnO films affect the performance of MIS.