Advanced Materials Research Vols. 476-478

Abstract: Polyacrylonitrile/montmorillonite (PAN/MMT) nanocomposite with amidoxime functionality was prepared from acrylonitrile monomer(AN) and montmorillonite(MMT) through in-situ intercalation polymerization. Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction patter (XRD) were employed to characterize the obtained Na-MMT、Organ-MMT、PAN/MMT、APAN/MMT. Effects of preparing conditions of APAN/MMT on adsorption of uranium were investigated. The FT-IR spectra show that the new absorption band at 1653 cm-1( ) appears and the absorption band at 2243 cm-1(-CN) disappears on the spectrum of APAN/MMT, it indicates that the AN and MMT are successfully polymerized by in-situ polymerization and the PAN/MMT is amidoxime functionalized. The APAN/MMT nanocomposite completely lose the X-ray diffraction. The adsorption results show that the obtained APAN-MMT gives uranium adsorption capacity of 3.06 mg.g-1 under following conditions: uranium ion concentration of 10 mg/L, AM mass concentration of 80.0%, initiator of 4.5%, polymerization temperature of 70 °C，polymerization time of 3 h, pH of 7 and amidoxime functionalized reaction time of 2 h.

Abstract: The mechanical and tribological properties of PA6/PPS blend reinforced by different content of carbon fiber were studied in the manuscript. It was found that the strength, modulus and hardness of PA6/PPS blend is improved apparently though breaking elongation rate and impact strength decreases to some extent. Average friction coefficient value of the carbon fiber reinforced PA6/PPS (PA6/PPS-CF) composites at the state stage is lower than PA6/PPS blend and PA6/PPS-CF10% exhibits the lowest friction coefficient of 0.34. As the content of carbon fiber increases, wear rate of the PA6/PPS-CF composites trends to increasing. These results is useful for providing some practical guidance for the application of polymer materials in the tribological field.

Abstract: Emulsion copolymerization of methyl acrylate, styrene, acrylamide, acrylonitrile and homemade cationic monomer was studied. A series of clean cationic polymethyl acrylate emulsion were synthesized using no soap emulsion polymerization. Influence of polymerization conditions such as cationic monomer ratio, electrolyte addition amount, the dosage of initiator on synthetic latex performance and the strengthening effect to paper pulp was studied. It was showed by experimental results that sample No.3 which particle size and zeta potential was 0.142 μm and +29.2 mv respectively was the optimal sample latex. When the dosage of latex No.3 was 1.0% to absolute dry pulp, tensile index and ring crush index of paper was increased by 14.6% and 17.8% respectively.

Abstract: A series of [Fe₈₀Ni₂₀-O/ZnO]_n multilayer thin films with different ZnO separate layer thicknesses (t, from 0 to 3 nm) and fixed Fe₈₀Ni₂₀-O layer thickness (about 5 nm) have been fabricated on (100)-oriented silicon wafers and glass substrates by reactive magnetron sputtering. Microstructure analysis and static magnetic measurement results indicate that the magnetic properties of the films can be adjusted by the variation of ZnO monolayers thickness. All films reveal an evident in-plane uniaxial magnetic anisotropy (IPUMA). The values of in-plane uniaxial magnetic anisotropy fields (H_k) and resistivity (ρ) can be changed from 8 to 57 Oe and 62 to 168 μΩ•cm respectively with the t increasing. While the values of hard axis coercivity (H_ch) and easy axis coercivity (H_ce) reveal minimums of 1.5 and 3 Oe respectively at t = 1 nm.

Abstract: Amorphous InGaZnO (a-IGZO) films are deposited on the glass substrate by RF sputtering and the influence of wet etching of a-IGZO films, etching rate, over etching features and TFT structure chose are investigated. The results show that Oxalic acid is best chose for IGZO film etching for side etching is about 0.1um , etching rate is 7.42 A/s which is easy to control and taper angle is acute. The traditional G-I-D type structure has been confirmed is not fit for the condition where the IGZO based TFT manufacture. G-D-I structure is tested and can be used in the TFT array manufacture.

Abstract: Hydrogenated amorphous carbon (a-C:H) films on silicon wafers were prepared by middle frequency pulsed unbalanced magnetron sputtering technique (MFPUMST) at different substrate bias under the acetylene-argon mixed gases. These films were characterized with Raman spectroscopy, atomic force microscopy (AFM) and nanoindentation. Raman spectra show that the sp3 fraction in a-C:H films increases with increasing substrate bias voltage from 0 to 100 V, and then decreases when the substrate bias above 100 V. AFM and nanoindentation results reveal that the surface roughness and nano-hardness of the films increase with increasing substrate bias voltage from 0 to 100 V, and then decreases when the substrate bias above 100 V. The mechanism of sputtering current on the sp3 fraction is discussed in this paper.

Abstract: A soluble polyimide (PI), 3,3’5,5’-tetramethyl-4,4’-diamino diphenylbutyltoluene- co-BPDA, was synthesized from 3,3’5,5’-tetramethyl-4,4’-diaminodiphenyl-butyltoluene and BPDA in m-cresol solution. The inherent viscosity of the resulting polyimide was 0.84 dL/g. Polyimide solutions in DMAc, with a concentration ranged from 14wt% to 34wt%, were electrospun into well-formed nanofiber membranes. The electrospinning parameters such as solution concentration, feed rate, applied voltage, and collection distance were optimized in order to reduce fiber diameter and distribution. The effect of LiCl and CTAB (Cetrimonium Bromide) on the elcetrospinning was also investigated. The obtained nanofiber membranes were characterized by SEM, TGA, XRD, and tensile test. With optimized electrospinning parameters the averaged diameter and the distribution of nanofibers could be reduced to 249 nm and 0.047, respectively. For the membranes, the temperature of 5% weight loss in nitrogen was 380°C and 10% at 534°C. The excellent thermal stability makes it could be used as high temperature filter materials.

Abstract: Nanocrystalline diamond (NCD) films were synthesized by hot-filament chemical vapor deposition (HFCVD) method at different temperatures (600 °C, 620°C, 640°C and 660°C). The AFM and Raman analyses demonstrated that deposition temperature has a great effect on the surface roughness and quality of NCD films and 620°C is the temperature to grow NCD films with smooth surfaces.

Abstract: The N-doped TiO₂ thin films of different pulsed negative bias and different current density were deposited on medical glass slide by arc ion plating. The influence of pulsed substrate bias and arc current on film properties was investigated by varying pulsed negative biases from 0 V to−600V and arc current from 40A to 60A. Film structure, surface morphologies and optical properties were measured with XRD, SEM and UV-VIS transmittance spectroscope. Photo-catalytic performance of the films was evaluated by degrading methyl orange. The results show that the N-doped TiO₂ films absorption edge successfully moved to 550nm and the films had better visible light response. Applying the negative pulse bias extended the absorption edge 5 nm - 40 nm, the absorption edge shifted towards the visible region with increasing arc current. The annealing treatment had a great impact on extending the absorption edge of the lower arc current, and the best extending can increase 64nm after annealing. The film surface roughness decreased with the increase of pulse negative bias, and the film surface grain size increased significantly after annealing. The N-doped TiO₂ film not only reduced the UV catalytic performance, but also extended its catalytic properties to the sun light.

Abstract: Ultra-high molecular weight polyethylene (UHMWPE) microporous membranes were fabricated via thermally induced phase separation (TIPS). Thermogravimetric analyzer was used to obtain the true concentration of films. To characterize the permeation property, the testing of water flux was carried out and it was found that with the increase of thickness, concentration and molecular weight, a decrease in water flux occurred. However, the water flux changed slightly when the thickness turned into 150μm and the molecular weight reached 4,000,000. Moreover, the pore structure investigated by Field emission scanning electron microscopy (FESEM) was consistent with the above phenomena. It is known that the pore size is affected by two factors: crystallization rate and the diffusion rate of diluent. The curves of the relative crystallinity (Xt) with time for the various films under the cooling rate of 10°C/min showed that the difference between crystallization rate of various membranes was small. So it was considered that the viscosity of system did greater influence on diffusion rate of diluent. In addition, the disparity between cloud points (Tcd) and crystallization temperature (T0) was not obvious, indicating that only solid-liquid phase separation could be observed in the range of cooling rates during the non-isothermal process.