Advanced Materials Research Vols. 418-420

Abstract: A new ultrasonication dispersion – microwave cure (UD-MC) method for preparing highly exfoliated layered epoxy/clay nanocomposites was developed. The process was divided into two consecutive stages. In the first stage, the epoxy and organoclay were mixed by high stirring and ultrasonication in the presence of acetone. In the second stage, the mixture of epoxy and organoclay was cured with microwave of 400W and postcured at 135°C. The microstructure of the nanocomposites was characterized with X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results indicated that the basal spacing of the organoclay particles in the epoxy/clay mixture was significantly enlarged, up to around 75Å afther the ultrasonic treatment. The layered clay was highly exfoliated under the microwave energy; and the basal spacing of nanolayers was more than 90Å.

Abstract: The spatial location of zerovalent iron nanoparticles hybridized with montmorillonite was identified with easily accessible X-ray diffraction, transmission electron microscopy, and element analyses. These hybridized nanoparticles are not intercalated into the interlayer space of clay whereas mainly located on the external surface of clay. This result would be of great importance for the sorption-based applications of these heterostructures.

Abstract: To expand the bandgap's width of the one-dimensional photonic crystal, a crystal named SiO₂/Metal/MgF₂ is formed by joining some metals into the crystal SiO₂/MgF₂. Furthermore the Finite Difference Time Domain (FDTD) method is used to explore the metals' influence on the crystal's transmission characteristics. The simulation results show that the metals joined could expand the width of the one-dimensional photonic crystal's bandgap effectively and the bandgap's width increases when the metals' thickness increases. Meanwhile the bandgap's characteristic is affected by the metals' material-characteristic. The higher the plasma frequency is, the wider the bandgap's width will be and the more the number of the bandgaps will be. On the other hand, the metals' damping frequency has no significant effect on the bandgap, but would make the bandgap-edge's transmittance decrease slightly.

Abstract: Barium titanate (BTO, BaTiO₃) nanofiber was prepared via electrospinning and followed annealing process. The as-spun and calcined BTO nanofibers were characterized by a scanning electron microscope (SEM). After annealing at 800 °C in air for 3 h, polycrystalline BTO nanofibers with 120-200 nm in diameter were successfully obtained. I-V characteristic curves of single BTO nanofiber were measured. The p-type semiconducting fiber shows a room-temperature conductivity of about 0.3 S/cm. In addition, the small humidity hysteresis demonstrates the application prospects of electrospun BTO nanofibers in the fabrication of a high-sensitive humidity sensor.

Abstract: In order to improve the hot strength of pre-cast shapes of high alumina castables used in industrial furnaces, the present work explored the approach to using in-situ formed mullite by incorporating 3%-9% silicon powders in bauxite based ULC castables. The pre-cast specimens were dried and then heated at 1450°C for 3h in air. The in-situ formed mullite derived from Si can remarkably improve HMOR of the castables. Refractoriness under load and TSR can also be improved by Si incorporation. The microstructure of the related castable samples was interpreted. The optimizing addition of Si power in this work is about 5%.

Abstract: Tung oil is a special biomass resource in China. Tung Oil has the characteristic to be transformed into serial derivatives for its active Conjugated double bond. Especially, tung oil anhydride-ester polyol (TOAEP) can be used as substitute of polyester polyol and/or polyether polyol in the synthesis and modification of polyurethane materials. Through esterification and transesterification, methyl-α-eleostearate-maleic anhydride adduct (MEMAA), a derivative of tung oil, was reacted with ethylene glycol and tung oil anhydride-ester polyol (TOAEP) was obtained. The optimal preparation condition are as follows: p-toluene sufonic acid is used as the catalyst, mole ratio of ethylene glycol to MEMAA is 4:1, reaction temperature is 120°C ~130°C, reaction duration is 8 h. Under the optimal preparation conditions, the yield of TOAEP is up to 88.8% and the hydroxyl value is up to 318.0 mg KOH/g. The structure of TOAEP was confirmed by Infrared spectroscopy (IR).

Abstract: A series of copolymer containing photoactive anthracene group, poly(N-dodecylmeth- acrylamide-co-anthrylmethylacrylate) p(DDMA-co-AnMA) were synthesized. Their molecular arrangement and photolithographic properties in Langmuir–Blodgett (LB) films were investigated. The copolymer p(DDMA-co-AnMA) could form stable monolayer at air/water interface and could be transferred onto solid supports, giving Y-type uniform LB films. The result showed that the irradiation with difference light wavelength leaded to changes of copolymer LB films in their chemical structure, concerning only the anthracence unit. When irradiated at 248 nm, the anthracene acted as photodecomposition group because of the peroxides. On the other hand, the main photoreaction induced by 365 nm is dimerization of anthracene. As a result, posotive-tone and negative-tone pattern could get by choosing a suittable irradiation light wavelength. Etching resistance of p(DDMA-AnMA) LB films was also investigated in a nanometer regime permitting etching of gold.

Abstract: Starch as the material, MBAA as the cross-linking agent, Tween60 and Span60 as the emulsifier, K₂S₂O₈-Na₂SO₄ as the initiator, the cyclohexane as the oil phase and the removal rate of methyl violet as an index, crosslinked starch microspheres (CSM) was synthetized by means of reverse suspension emulsion and graft-copolymerization method through orthogonal test and single factor optimization experiment. The results showed the optimal conditions of the preparation of the crosslinked starch microspheres(CSM) were as follow: the concentration of the starch is 5%, the dosage of the MBAA, initiator and emulsifier are 0.125g, 0.5g and 0.6g, the volume ratios between the Span60 and Tween60 is 85:15, and the volume ratio between the cyclohexane and water is 4:1.

Abstract: In this paper, the explosion experiments of Indonesia pulverized coal cloud are carried out. The pressure histories are recorded. The maximum pressure, the maximum pressure rising rates and the explosion time are analysed based on the pressure histories. The experiment results indicate that with the increase of pulverized coal concentration, the maximum explosion pressure and maximum pressure rising rate at first increases, then decreases, and the explosion time is contrary to that.

Abstract: Metallic-doping chalcogenide compounds have attracted significant interest in application of photovoltaic devices recently. In this article, Al-doped SnS films with a thickness of about 500 nm have been deposited on glass substrates by thermal evaporation technique. Al-doping concentration (from 0 at. % to 15 at.%) in the SnS films can be controlled accurately by varying Al layer thickness. The effects of Al–doping on the physical properties of the films have been investigated by X-ray diffraction, scanning electron microscopy, ultraviolet-visible-near infrared spectroscopy measurements and Hall effect measurement system. All the films are orthorhombic SnS with preferred (111) crystallites orientation, and they are of p-type conductivity. With the increasing of Al-doping concentration, the evaluated direct band gap Edir of the SnS: Al films decreases from 1.50eV to 1.29eV and the conductivities of the films increase. Therefore, the optical and semiconducting properties of the SnS films have been improved by Al-doping.