Advanced Materials Research Vols. 455-456

Abstract: Unsaturated polyester resin/Graphite nanosheet composites were prepared using in situ polymerization under AC electric field which was applied during composite curing to induce orientation of graphite nanosheets. Scanning electron microscopy (SEM) has been applied to demonstrate the orientation of graphite nanosheets As a result, the percolation threshold was decreased to 0.25 wt% due to the orientation of the graphite nanosheets.

Abstract: As conductive fillers, graphite nanosheets can be induced by the AC electric field in unsaturated polyester resin and then prepared oriented unsaturated polyester resin/graphite nanosheets composite. we investigate the preparation、configuration and capability of the unsaturated resin/graphite nanosheets conductive composites and the oriented theory of the graphite nanosheets induced in the electric field. The measures and observation of scanning electron microscopy (SEM), X-ray diffraction (XRD), electric current have shown that the graphite nanosheets are oriented by electric field which were randomly dispersed in the polymer matrix at the beginning, and then oriented with their flakes along the electric field in the polyester resin.

Abstract: Graphite nanosheets (GNs) prepared by sonicating expanded graphite were homogeneously dispersed in unsaturated polyester resin using sonication. The dispersion with a curing agent was then subjected to a dc electric field, followed by crosslinking, to fabricate a polymer/GN composite film. Scanning electron microscopy revealed that the GNs in the film were oriented parallel to the electric field. UV-VIS measurements indicated that the optical properties of the field-induced composite film showed significant improvement in visible light transmittance compared with those prepared without the electric field.

Abstract: The hydrocracking of a pentane-insoluble asphaltene over NiMo/γ-Al₂O₃ was investigated in a microbatch reactor at 703 K. The cracking kinetics of the asphaltene was analyzed on a total molar basis. The first-order kinetics fits the experimental data in reaction times ≤30 min adequately, to give the rate constant of 0.0498 min^-1. For reaction times over 30 min, however, secondary reactions such as coke formation could become significant. The formation probability of gas products decreases from the initial value of circa 0.8 to a stable level of 0.6 in 30 min, and the formation probability of liquid products increases from 0.2 to 0.4 accordingly.

Abstract: Pyrolysis of cyclohexane was conducted with a plug-flow tube reactor at 873 K. The data of feed conversion fit first-order kinetics adequately, giving the apparent rate constant of 0.0092 s^-1 . A chain mechanism of free radical reactions is proposed to interpret consumption of cyclohexane by four processes: homolysis of C-C bond (Path I) and homolysis of C-H bond (Path II ) in reaction chain initiation, H-abstraction of various radicals from feed molecule in reaction chain propagation (Path III ), and the process associated with coke formation (Path IV). The reaction path probability ratio of X _I：X _II：X _III ：X _IV was 0.5420: 0.0045 : 0.3897 : 0.0638.

Abstract: Monodispersed nanotriangles of gold have been prepared by a simple reaction between HAuCl₄·4H₂O, KOH and NH₂OH·HCl in the presence of gelatin. Gelatin played a decisive role as an inhibitor of the direct reaction of NH₂OH with AuCl₄- and coagulation of the growing gold in producing the triangle. In the absence of gelatin, we can only obtain irregular large gold particles. The products were characterized by X-ray powder diffraction, transmission electron microscopy and UV-visible absorption spectroscopy.

Abstract: The failure of magnet wires used in inter-turn insulation of inverter-fed motor winding is the main cause which leads to the motor insulation breakdown. This paper conducted electrical tree breakdown experiments on magnet wire insulating film (FCR 100) used in the inter-turn insulation of JD117 inverter-fed motor and meanwhile combining with energy spectrum analysis and scanning electrical microscope (SEM), by which type and content of elements, breakdown main body and electrical tree channel could be clearly observed, the corresponding failure mechanisms were analyzed. The experiment results reveal that all the breakdown main bodies are located at the pointedness and insulation joint of magnet wires, of which dielectric strength is relatively lower; they are the insulation “weak point”, which should be paid enough attention and strengthened at the manufacturing period. The electrical tree breakdown time is quite long and the life span of magnet wire is 11 hours. The electrical breakdown strength of envelope is very low when containing metal impurity. It is also found that the aluminum occupies the highest content tested by energy spectrum analysis.

Abstract: A bi-component copolymer/layered silicate nanocomposite was synthesized by way of a two-stage radical copolymerization of emulsion intercalation and solution intercalation, using acrylates, methacrylic acid and acrylamide as monomers. The water-based product was designed with a structure of a hydrophobic copolymer dispersed in an aqueous copolymer solution to meet needs of warp sizing agents on adhesiveness to hydrophobic and/or hydrophilic fibers, appropriate glass transition temperature, as well as water-solubility. XRD patterns for the product films showed an exfoliated structure of montmorillonite (MMT) in the part of soluble acrylic copolymer as the MMT content equal to or less than 7%, while in the part of emulsion copolymer alone or the product as a whole, the MMT showed an intercalated structure. Determination of DSC indicated that chemical bondings occured between the hydrophobic and hydrophilic components, which guaranteed storage stability of the system and water-solubility of the sizing film, and that there were three T_gs corresponding to the emulsion copolymer, solution copolymer and the interfacial copolymer between the two phases. All the T_gs increased with increasing content of the MMT in the composites.

Abstract: In order to explore high strength organic electrotransporting electroluminescent (EL) materials, twelve new pyrazole oxadiazole compounds containing the benzothiazole or benzene group in the 1 position of pyrazole, the aromatic group in the 3 position of pyrazole and the formacyl group in the 4 position of pyrazole were designed and synthesized. A new method of synthesizing 1,3,4-oxadiazole compound was described. Their structures were characterized by IR, MS, ¹H NMR spectra and elemental analysis. The fluorescence properties were measured by fluorometry. The results showed that the target compounds had good fluorescence and λ_em ranged from 410nm to 450 nm and fluorescence quantum yields up to 0.69.

Abstract: The modified starch was prepared by degradation starch with glutaraldehyde. The process conditions of degradation and modification starch were investigation. The result shows that the degradation starch was obtained through 22.5 g cornstarch and 1g ammonium persulfate (APS) in 127.5 g water at 95°C for 1h, and the modified starch was obtained by aldolization reaction of degradation starch and 4 mol/AGU glutaraldehyde at 85°C for 5h. The modified starch can be used as leather tannage. The shrink temperature (T_s) of tanned leather can be increase from 41.6 °C to 85.2°C. It may replace chrome tannage and decrease the pollution produced in chrome tanning processing. Meanwhile, the chemistry structure of modified starch was characterized by FTIR, ¹H-NMR, ¹³C-NMR