Advanced Materials Research Vols. 785-786

Abstract: In this paper, adherend thickness influence on the bond strength was evaluated by single-lap shear testing. The adherend for joining was carbon/epoxy composites with four different thickness made of fabric prepregs. The adhesive system for joining included two types of adhesive film, namely J-135 and J-95. The results showed that adherend thickness have a significant influence on the bond strength. In the range of adherend thicness from 2.26 mm to 4.52 mm, the bond strength demonstrated a wavy change with increasing adherend thickness. Through comparison of the bond strength of joints with two adhesives at room temperature and aging condition, adhesive J-95 was proved to have better resistance to elevated temperature and humidity than J-135.

Abstract: A new unburned brick was prepared from the Ti-bearing blast furnace slag as an aggregate and PVA modified by epikote as cementitious materials. The effects of modified PVA and auxiliaries on compressive strength of unburned brick were studied by the orthogonal test method. The results show that samples have better properties and low cost when the samples have a composition of slag dosage 72 %, modified PVA dosage 6%, auxiliary 1 dosage 6%, auxiliary 2 dosage 10%, water 6% and the process conditions of preparing the brick sample were mixing time 1 h, forming time 10 min, forming pressure 40 MPa, and curing time 7 d. The study reveals that the samples properties can meet the standard requirements of excellent grade products (MU20) in GB11945-1999.

Abstract: The thermochromic vanadium dioxide was successfully synthesized by thermal treatment of a metastable VO₂ (B) prepared by hydrothermal process at 180 °C for 48 h with oxalic acid in nitrogen atmosphere. Both annealing temperature and amount of oxalic acid have an effect on phase transformation of VO₂ (B) to VO₂ (M). Various techniques such as SEM, XRD and DSC were used to characterize the morphology, phase composition, and phase transition temperature, respectively. The transformation of VO₂ (B) to VO₂(R) increased with an increase in treatment temperature. Moreover, the addition of oxalic acid in heating process exhibited completely transformation of VO₂ (B) to VO₂ (M).

Abstract: In order to study in vitro release behavior of hydrophilic drugs in polymer nanofibers and establish a fast characterization method, tetracycline hydrochloride-loaded poly (lacticacid-co-glycolic acid) nanofiber mats with varied tetracycline hydrochloride contents and different lacticacid to glycolic ratios in PLGA were preparied by electrospinning. Accroding to Chinese Pharmacopoeia, a basic and an improved test devices and processes were compared and their validity were commented by using an UV-visible spectrophotometer method. Results showed that the improved method can be used to estimate in vitro drug release behavior of drug-loaded mats and the results was better than the basic method. When temperature affected cumulative release ratio under controlled error, flotation method can replace the centrifugation method during the first stage of drug release testing process. Parallel experiments were carried out and results indicated that nanofibres on different part of mats had a relative stable result and repeat experimental error was kept below 4%.

Abstract: The pretreatment of bamboo fiber by the sulfuric acid was investigated by means of experiments. Effect of the sulfuric acid concentration, reaction temperature, hydrolysis time, and solid-liquid ratio on the yield of Cellulose Nanocrystalline (CNC) was studied by orthogonal experiments and single factor experiments. Pretreatment with 60% sulfuric acid and 1:8 solid-liquid ratio for 90 min at 45°Cwas found to be the most optimal condition for pretreatment of bamboo powder for CNC. After pretreatment at the optimal condition, 30.2% of theoretical yield was obtained. Meanwhile, the study of rheological properties showed that CNC had a shear thinning phenomenon, the viscosity of CNC varied in different temperature and different concentrations. We can draw the conclusion through Transmission electron microscopy (TEM) that CNC was mainly existed in two forms of rod and porous network, and had a basic chemical structure of cellulose, while the molecular internal hydrogen bonds were destroyed.

Abstract: Silver nanowires in large quantities can be obtained by 5-hydroxy-L-tryptophan through a simple method in the absence of a surfactant and seed. The influences of different experimental parameters on the morphologies of silver nanoproducts in such an environmentally friendly synthesis were investigated. Different molar ratio of reactants which can results different size and shape of silver nanoparticles. The high temperature, the acid or alkaline condition is not to facilitate formation of the nanowires. This simple and eco-friendly preparation method of silver nanowires can decrease the synthetic cost and broaden the research and application areas of silver nanowires.

Abstract: Foam is a thermodynamically unstable system, and the stability is the most important factor for the preparation and application of foams. In this paper, the effect of ZnO powders on the stability of the foams stabilized by sodium dodecyl benzene sulphonate (SDBS), hexadecyl trimethyl ammonium bromide (CTAB) and Polyethylene glycol tertoctyl phenyl ether (TritonX-100) was investigated. The results showed that ZnO powders have a synergistic effect with SDBS and CTAB. There is no synergy between ZnO powders and Triton X-100. The mechanism for the stabilizing effect of ZnO powders on the foams was discussed.

Abstract: Anatase crystalline TiO₂ aeroge and TiO₂ aerogel doped with Fe³⁺ were prepared at low temperature (60°C) using ionic liquid (IL) assisted sol-gel method. In this system, ionic liquid was not only an effective solvent but also an important template, which enhanced the polycondensation and crystallization rate, facilitated the formation of anatase crystal. Due to the effect of template, anatase crystalline TiO₂ aerogel can be synthesized at the aging temperature of 60°C and drying under ambient pressure. The as-synthesized samples were characterized by X-ray power diffraction (XRD), scanning electron microscopes (SEM). The photocatalytic performance of pure TiO₂ aerogel and TiO₂ aerogel doped with Fe³⁺ aerogel was evalutaed by decolorization of reactive brilliant blue under visible light irridation. The results indicated that TiO₂ aerogel doped with Fe³⁺ exhibited higher photocatalytic activity than pure TiO₂ aerogel and Degussa P25.

Abstract: In this paper, we demonstrated a simple and efficient method to synthesize Ag nanoparticles (NPs) using commercial and highly active baker's yeast as a stabilizier and reducing agent, which got rid of the cumbersome steps to cultivate yeast. Ag NPs could be formed within 2 min at pH value higher than 8 when silver ion react with the yeast. The effect of pH on the extracellular synthesis of Ag NPs was investigated. The results indicated that the optimized pH value was above 8. The biosynthesized Ag NPs had absorption peaks at 413~455 nm corresponding to their surface plasmon resonance. SEM and TEM images showed that the nanoparticles were uniformly monodisperse and spherical with the size of around 5~25 nm.

Abstract: A liquid phase method to synthesize gold nanoparticles (NPs) has been studied by reducing tetrachloroauric acid (HAuCl₄) with the culture medium of baker’s yeast. In general, the reducing substances in the culture medium of baker’s yeast can be divided into two categories: the metabolites and the organizations. Herein the reducing agents are mostly metabolites, along with some other components of the cells that are overlooked in the process of filtering. Different sizes of gold NPs have been obtained by merely varying pH of the medium, with size of the nanoparticles of 5~30 nm. Several characterizations have been carried out to confirm and analyze our products, such as UV-vis spectra, field emission scanning electron microscope (FE-SEM) images, transmission electron microscope (TEM) image, energy dispersive spectrum (EDS) and selected area electron diffraction (SAED) patterns. In the future study, the smaller ones can be treated as a good substitute of the traditional seeds synthesized with some chemical surfactants.