Applied Mechanics and Materials Vol. 749

Abstract: Graphene nanosheets (GNSs) with different oxygen contents crucially affect the performance of polymer composites. In this study, we compared GNSs prepared from graphite oxide (GO) using three different concentrations of potassium permanganate and thermal reduction of GO at 1050 °C. The structural properties of GO and GNSs were investigated by Fourier transform infrared spectroscopy and Raman spectroscopy. Moreover, an effective coagulation method was used to prepare poly (trimethylene terephthalate) (PTT) composites filled with well-dispersed GNSs by selecting suitable solvents for solution blending. The electrical properties of PTT/GNSs were investigated to reveal the effect of oxygen content of GNSs.

Abstract: Heterostructure of Ag/ZnO was synthesized by a reduction of Tollen’s reagent on ZnO powders. The photocatalytic activity of Ag/ZnO was investigated through the degradation of three different dye solutions (methylene blue, rhodamine B and reactive orange 16) under visible light using the fluorescent lamps with a 420 nm longpass filter. The efficiencies of dye degradations for all three dyes by Ag/ZnO are better than that of pure ZnO. Furthermore, the parameters including photocatalyst loadings and initial pHs of dye solutions were also studied. The photocatalytic degradations for all three dyes were increased with the increasing of catalyst loadings. The effect of pHs on photocatalytic activity of Ag/ZnO can be explained by the interaction between the charge on the surface of photocatalyst and the charge of dye ions.

Abstract: Glass-ceramic was precipitated on the oxyfluoride glass surface by thermal annealing with a CO₂ laser and a heat gun. Micro x-ray diffraction showed the formation of CaF₂ ain the exposed region to the laser. Dopant distribution in glass ceramics was probed by confocal fluorescence microscope by observing much strong emission from Eu ions than the glassy area under 405 nm excitation. Much enhanced visible emissions under 365 nm excitation also showed well incorporation of Eu³⁺ ions into a crystalline environment.

Abstract: Spinel ZnCo₂O₄ nanosized powders were prepared by decomposing of the metal nitrate solutions at 100 °C. Structural properties of the sample were investigated by using powder X-ray diffraction (XRD), UV-visible and High resolution transmission electron microscopy (HR-TEM) techniques. Spinel crystal structure of the sample is confirmed by XRD analysis. The average crystallite size of the samples is found about 60 nm by Williamson-Hall analysis. The average grain size and crystalline nature of the samples is further confirmed by using the HR-TEM analysis. The band-gap energy is found to be 2.67 (±0.03) eV. Electrical properties were studied by two probe ac impedance spectroscopy. Dc conductivity is temperature dependent and found to obey the Arrhenius behaviour. The gas sensing behaviors were investigated by using dc and ac impedance measurement methods. It shows the promising gas sensing behavior for liquefied petroleum gas.

Abstract: Chitosan and gelatin has attracted considerable interest owing to its advantageous biological properties such as excellent biocompatibility, biodegradation, and non-toxic properties. In this paper, we investigated the potential of chitosan/gelatin (Chi-Gel) nanofibers mat with enhanced cell viability for use as cell culture scaffolds. The surface morphology, mechanical properties, and initial contact angle analysis of Chi-Gel nanofibers mat were evaluated. The proliferation of human dermal fibroblast cell (HDFs) on Chi-Gel nanofibers mat was found to be approximately 20% higher than the pure chitosan nanofibers mat after 7 days of culture. These results suggest that the Chi-Gel nanofibers mat has great potential for use tissue engineering applications.

Abstract: In this research, waste of Aren fiber is utilized for raw material of composite. This aren fiber composite is used for insulator and sound absorber. The Aren composite is manufactured by pressing technique of mixture of aren, resin and hardener occur for 24 hours. The composites made from aren composite are tested in term of thermal conductivity and ability of sound absorber. The research aims to study an effect of resin to fiber ratio, size of Aren fiber to thermal conductivity, and sound absorber ability of aren composite material. The result shows that the optimum thermal conductivity of Aren composite is found to be 0, 3950 kcal/m h0C. This composite is obtained with resin-fiber ratio of 7:1, fiber length of 1 cm, 10% hardener, and pressure of 70 kg/mm2. Meanwhile, for optimum sound absorber composite is obtained with resin-fiber ratio of 6:1, fiber length of 2 cm, 10% hardener, and pressure of 70 kg/mm2. The composite has noice reduction of 40,1 dB and transmission loss of 46,1 at frequency of 500 Hz.

Abstract: This research is the application of new design method for integrating the optimum shape and strength design process. The products is manufactured from product design which can use the advanced characteristic of composite materials obtained by the experiment and the numerical analysis. Here, the collaboration of the design and the strength analysis by using composite materials is carried out. The products, which are made from high strength composite materials, need new product design technology which draws out the characteristic of material's advantage. Existing product developments tend to separate product design from product planning. The process consists of three stages as follows; 1) Planning the shape of the product by designers, 2) Calculating the strength by numerical analysis, 3) Designing the product. It is performed a styling design by requirements from the engineering point of view. By using this design method of high-strength materials, we designed new styling ZIGZAG Chair made of the carbon fiber reinforced plastic with excellent strength and lightweight.

Abstract: This study purposes to investigate acoustic absorbing and puncture resisting properties of wall covering composites with different number of layers, and then to construct prediction model of acoustic absorption coefficient. Puncture resistance linearly increases but maximum absorption coefficient shifts to lower frequency with number of layers.The acoustic absorbing property of wall covering composites presents porous acoustic-absorbing characteristic, and its prediction model correlates with critical frequency and maximum absorption coefficient. The resulting coverings have excellent puncture resistance and acoustic absorbing properties.

Abstract: The present study aims to investigate the effects of the ratio of different rubber threads on the elastic, tensile, air permeability, andfar-infrared emissivity properties ofelastic warp-knitted fabric. Polyester filaments and rubber threads were applied as warp yarns while bamboo charcoal (BC)/Nylon (NY) filament was used as weft yarn to fabricate elastic knitted fabric (EKF) by using Velcro Crochet Machine. The four different ratios of rubber threads in warp direction were 0 %, 25 %, 50 % and 100 %. The result revealed that with the increase in weight ratio of the rubber thread, the air permeability decreased while the tensile elongation tended to increase in both warp and weft directions.

Abstract: This study examines how the counts of PET yarns and spandex fibers influence the properties of tubular knitted fabrics. PET yarns and spandex fibers with different counts are combined to form wrapped yarns, which are then made into tubular knitted fabrics. The surface of the knitted fabrics is observed, after which the knitted fabrics are tested for their tensile strength. The test results show that the tensile strength and thickness of the tubular knitted fabrics both increase as a result of the increasing content of PET yarns; however, the content of either spandex fiber or PET yarns is not correlated with the deformation of the tubular knitted fabrics.