Advanced Materials Research Vols. 239-242

Abstract: Studies on interfacial compatibility of wood plastic composites(WPCs) have received considerable attention in recent years. The effects on the surface modification by cellulase treatment and the mechanical properties of prepared WPCs were investigated in this study. X-ray diffraction(XRD) results show that the relative crystallinity(RC) of Hybrid Pennisetum(HP) could be significantly changed by the cellulase treatment. The RC of HP powders mainly goes through a phase that it first increases and then decreases by the treatment of cellulase. Five groups of different cellulase dosage and different treatment time were selected to do the mechanical and DMA tests. With proper dosage of cellulase and treatment time, the mechanical properties of WPCs could be improved. Finally, in the case of HP powder/cellulase of 4/1 and treatment time for 2 hours, WPCs show the best performance.

Abstract: A new diarylethene of 4-bromo-1-phenylethynylphene was synthesized. It is a kind of conjugated organic molecular that simulated the structural features of left-handed material. The compound turns out to be a single-crystal. Its properties, including X-ray single-crystal diffraction analysis and optical property were investigated in detail.

Abstract: A new water-based strippable protected coating was made by polyurethane emulsion and nano-CaCO₃ was put in the coating as the fillers. The influence of nano-CaCO₃ on the coating was discussed and the influence of film thickness on the coating was studied. The performance of the coating was tested, and when the dosage of nano-CaCO₃ was 2% and the film thickness was 0.13~0.14mm, the film had the best strippable ability. Its average mechanics intensity was 5.72MPa and average elongation at break was 258.35%.

Abstract: According to the mechanisms of carbon dioxide miscible flooding and previous researchers’ work on synthesis of CO₂-soluble surfactant, Citric acid isoamyl ester was synthesized, and it’s oil solubility and the rate of viscosity reduction both in oil-water system and oil were evaluated. And then we found that this compound can solve in oil effectively; the optimum mass of Citric acid isoamyl ester introduced in oil-water system is 0.12g when the mass ratio of oil and water is 7:3 (crude oil 23.4g, formation water 10g) and the experimental temperature is 50°C , the rate of viscosity reduction is 47.2%; during the evaluation of the ability of Citric acid isoamyl ester to decrease oil viscosity, we found that the optimum dosage of this compound in 20g crude oil is 0.2g when the temperature is 40°C, and the rate of viscosity reduction is 7.37% at this point.

Abstract: A series of polyimide composites with various mass fractions of multi-walled carbon nanotubes (MWNTs) were prepared by in situ polymerization. MWNTs were treated with an acid mixture and sulfoxide chloride in turn to increase the chemical compatibility of carbon nanotubes with the polyimide matrix. The modified MWNTs are dispersed homogeneously in the matrix while the structure of the PI and MWNTs structures are stable in the preparation process. The composite films hold preferable thermal stability as same as the pure PI. The dielectric constants of the composites decreased with the increasing frequency and increase sharply with the adding of MWNTs.

Abstract: Study on the preparation processing of E-ACE.By experimental methods, the conductivity, the mechanical flexibility of the electrode material and the thickness of the acrylic polymers were studied respectively. Experimental results show that the conductivity of electrode material have an impact on the performance of E-ACE, E-ACE performance is enhanced with the increasing of conductivity of the electrode material. Mechanical flexibility of Electrode materials and thickness of acrylic polymer have significantly impact on the performance of E-ACE, E-ACE performance is enhanced with the decreasing of mechanical flexibility of electrode material, and E-ACE performance is also enhanced with the decreasing of the thickness of acrylic polymers.

Abstract: 0.85(Na_0.5Bi_0.5)TiO₃-0.144(K_0.5Bi_0.5)TiO₃-0.006BaTiO₃(0.85NBT-0.144KBT-0.006BT) lead-free piezoelectric ceramics was prepared by conventional ceramic technique. The influence of La₂O₃ doping amount and CeO₂ doping amount on properties , crystal structure and surface topography of 0.85NBT-0.144KBT-0.006BT ceramics were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and other analytic methods. It shows that all compositions show the characteristics of pure perovskite structure solid states, La₂O₃ and CeO₂ doping only changes crystal cell dimension rather than crystal structure. The piezoelectric strain constant (d₃₃) starts increasing and then decreasing, the dielectric constant (ε^T₃₃/ε₀) increases, the dielectric loss (tanδ) starts increasing and then decreasing and then increasing while La₂O₃ doping amount increasing. d₃₃ and ε^T₃₃/ε₀ of ceramics starts increasing and then decreasing, tanδ decreases while CeO₂ doping amount increasing . When the La₂O₃ doping amount is up to 0.4 wt.%, the doped samples show good performances with d₃₃=151 pC/N, ε^T₃₃/ε₀=1543 and tanδ=4.3%. When the CeO₂ doping amount is 0.1 wt.%, the doped samples show good performances with d₃₃=156 pC/N, ε^T₃₃/ε₀=1364 and tanδ=3.8%. La₂O₃ doping promotes crystal grain growth, CeO₂ doping makes grain crystal size uniform, changes tetragonal into granular structure and restrains crystal grain growth.

Abstract: Bacterial cellulose (BC) gelatinous films prepared in stationary culture were dried by three different drying methods: hot air drying, vacuum drying and vacuum freezing drying. The structure of dried bacterial cellulose films was characterized using scanning electron microscopy (SEM), infrared spectroscopy (IR) and X-ray diffraction (XRD), and mechanical properties were tested. The results showed that the surface of films prepared by hot air drying were uniform and dense, cavities and cracks configurations existed in vacuum dried films, and layer and porous structures were observed in vacuum freezing dried films. FTIR spectra and X-ray pattern confirmed that vacuum freezing drying reduced the strength of hydrogen bonds between cellulose macromolecules and the degree of crystallinity of BC films but had little influence on the crystal structure. For those reasons, mechanical properties of BC films prepared by vacuum freezing drying were lower than that of those films by other methods.

Abstract: TiO₂ and Sn⁴⁺-doped TiO₂ were prepared by sol-gel method and characterized by the techniques such as XRD, SEM and DRS. The photocatalytic degradation of methylene blue (MB) in aqueous solution was used as a probe reaction to evaluate their photocatalytic activity. The matrix distortion of TiO₂ increases after Sn⁴⁺ doping and a blue-shift of the absorption profile are clearly observed. The results show that doped Sn⁴⁺ inhibits the phase transformation of TiO₂ from anatase to rutile, decreases the diameter of TiO₂ and significantly enhance the photocatalytic activity of TiO₂. The Sn⁴⁺-doped into TiO₂ exert a synergistic effect on their photocatalytic activity.

Abstract: We demonstrate a novel approach to produce micron sized shape-memory beads from polyurethane shape-memory polymer (SMP)-dimethylformamide (DMF) solution by joule heating carbon fibers. The relationship between the geometrical dimensions of the resultant SMP beads and processing condition is obtained, which shows the convenience in dimension/size control in fabrication. The fabrication mechanism is revealed and good shape-memory effect is proved.