Advanced Materials Research Vols. 233-235

Abstract: Surfactant hydrogels were prepared composed of sodium dodecyl sulphate(SDS) /Al(NO₃)₃ /H₂O systmes. Steady and oscillatory shear experiments were carried out to evaluate the inner structure of the gel with variable Al(NO₃)₃ concentration at a fixed SDS 20wt% composition in gel region. The results indicated that hydrogels showed shear-induced thinning nonlinear rheology behaviors. Phase transition was measured by differential scanning calorimetry and the transition temperature(T_gel) increased with aluminum salt concentration increasing. It is in conformity with electron micrograph of microstructures from spherical, short rod-like to larger cylindrical micelles. Littler salt change resulted in larger micelles transition derived from supramolecule structure of SDS and Al³⁺.

Abstract: Rectorite (REC), humic acid (HA) and polyvinyl alcohol (PVA) were used to prepare microspheres. Batch adsorption experiments of Pb²⁺ ion on to the microspheres were performed. The results obtained indicate that adsorption time, the microspheres dosage and temperature were the main factors influencing the adsorptive capacities. The adsorption data for Pb²⁺ ion were well described by the Freundlich, Langmuir and Temkin models. The kinetic experimental data properly correlated with the pseudo-first-order model, pseudo-second-order model and Elovich equation. The adsorption process is spontaneous, endothermic and out-of-order. The whole adsorption process is mainly controlled by entropies. The adsorption can be classified as chemical adsorption. The mechanisms for the adsorption of Pb²⁺ ion on to the microspheres involved ion-exchange adsorption of Pb²⁺ or the formation of complex compound. Under the experimental conditions employed, the removal of Pb²⁺ ion attained value of 96.05%.

Abstract: The sulfonated polystyrene hollow microspheres (SPHS) with interpenetrated walls were used as templates. An in-situ growth of BaTiO₃ nanocrystals was conducted against SPHS templates at ambient pressure and 70°C. The structure and morphology of the resultant samples were investigated by XRD, SEM, TEM, FTIR and TGA. The results indicated that the composite hollow microspheres with diameter about 450 nm were double-shelled and composed of 30 nm cubic BaTiO₃ nanocrystals.

Abstract: Impacts of packaging conditions on shelf-life quality of fresh-cut ‘Lushanxiang’ kiwifruit were investigated during 12 d of storage at 4 °C. Fruit slices were wrapped in 64 μm polypropylene (PP) film flushing with high CO₂ (40% or 10%) atmosphere or passive modified atmospheres (air). Measurements of firmness, total phenolic content, chlorophyll and microbial growth were evaluated over time. Active packaging with the initial 10% CO₂ plus 5% O₂ was the most effective in maintaining flesh firmness, total phenolic and chlorophyll content, which was still 11N, 0.75 mg/mL and 0.09 mg/g respectively. Both 40% and 10% CO₂ active modified packaging significantly inhibited the microbial grows. Further researches are needed to evaluate the sensory aspects, as well as to characterize the flesh translucency phenomenon of fresh-cut kiwifruits.

Abstract: In this paper, poly (m-xylylene adipamide-terephthalyl amide) (MXD6T) and silicon dioxide (SiO₂) nanocomposite with SiO₂ load from 5% to 20% (by mass) is prepared and used to improve the barrier property of polyester bottle materials. In preparing MXD6T-SiO₂ (NMXD6T), silica is in-situ polymerized with hexane diacid, terephthalic acid (TPA), alkyl and aromatic diamine. The different molar ratio of hexane diacid to terephthalic acid with the same molar diamine is designed to give the composites with different viscosity, thermal performance and the barrier properties. The 3-8 times of enhanced permeability of these polyester matrix nanocomposites with this NMXD6T to pure polyester resins are reported. The relationship of NMXD6T’s configuration and the permeability properties of polyester nanocomposites are characterized. DSC shows that NMXD6T is totally amorphous. FTIR shows the existence of silicon-oxygen bond formed in the nanocomposite, and TEM indicates an average size from 30nm to 100nm of SiO₂ particles being phase separated from MXD6T matrix, while well bonded to the polyester chains.

Abstract: An electrochemical sensing device with a plasticized polyvinyl chloride (PVC) membrane electrode based on a porphyrin derivative of p-amino tetraphenyl porphyrin (p-NH₂TPP) for mercury ion (Hg²⁺) has been fabricated. The p-NH₂TPP based PVC membrane electrode exhibited a nice linear potential performance for responding to Hg²⁺ in the range of 1.0×10^-8 ~ 1.0×10^-3 mol/L with a slope of 27.54 mV/-pC (25°C) in citrate buffer solution (pH=2.5). The detection limit was evaluated to be 7.5×10^-9 mol/L. No obvious interferences were observed from Na⁺, K⁺, Ba²⁺, Mg²⁺, Ca²⁺, and Cr³⁺. The electrode possessed good stability and reproducibility. Comparing with atomic absorption spectroscopy (AAS), the electrode can be well applied to the determination of trace amount of Hg²⁺ in environmental waste water samples with a recovery rate of 94.83 ~ 104.78%. The sensing mechanism of the porphyrin derivative carrier for recognition of Hg²⁺ has also been expounded by the formation of nice complexation effect between the lone pair electrons provided by four nitrogen atoms of the porphyrin molecule and unoccupied orbitals provided by the mercury ion.

Abstract: The rheological behavior of PA6/montmorillonite(MMT) by reactive extrusion was investigated using cone-and-plate rheometer. The experimental results indicated that PA6/MMT exhibited shear-thinning behavior. The shear stress of both neat PA6 and PA6/MMT increased with the increase in the shear rate. The reduction of the viscous activation energy with the increase of shear stress reflected PA6/MMT can be processed over a wider temperature.

Abstract: Four kinds of polymer emulsions were coated on the surface of coal pitch carbon fiber using atomized flow static coating method. The surface morphology of the carbon fiber after modification was analyzed by fluorescence microscope.The tensile strength of coated carbon fiber in the cement mortar and the mechanical property of the coated carbon fiber reinforced concrete were tested. The results showed that all the polymer emulsions were coated successfully on the surface of carbon fiber. The tensile strength of the coated carbon fiber in the cement mortar increased obviously, specially for the carbon fiber coated by meta chloride copolymer emulsion, whose tensile strength improved by 61%. The tensile strength of the coated carbon fiber reinforced concrete increased by 11%, the fracture energy increased by 47% and the max crack width increased by 18.5% when the content of the carbon fiber coated by meta chloride copolymer was 1.7 kg/m³.

Abstract: The pH value and SO₄^2- concentration in corrosive environment may affect mechanical property of cemented soil inturn to cause some serious damage to structure. The results of tests show that the unconfined compression strength is decreasing with the increase of H₂SO₄ solution concentration, increasing with the increase of pH value. The pH value is increasing and the SO₄^2- concentration is decreasing with the increase of corrosive time. So it is concluded that compressive strength is closely rated with the pH value, SO₄^2- concentration of corrosive environment and corrosive time. Finally a equation is set up based on the relationship of compressive strength and factors affected, which contain the reduced coefficient of compressive strength, pH value, SO₄^2- concentration and corrosive time. The calculated and measured values are close so that the equation could be used in practical design for reference.

Abstract: Ti-SBA-15 mesoporous materials were directly synthesized via a hydrothermal process and characterized by using nitrogen adsorption-desorption measurements, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, diffuse reflectance ultraviolet-visible spectroscopy, and infrared ray spectroscopy. The effect of synthesis temperatures on the structure and catalytic efficiency in epoxidation of cyclohexene was discussed in details. The results showed that the optimal temperature was 100 °C under the reaction conditions.