Advanced Materials Research Vols. 160-162

Abstract: In this investigation, nano-scale hydroxyapatite (HA) particles were incorporated in poly(hydroxybutyrate-co-valerate) (PHBV) polymer to fabricate composite films using solvent casting method. The morphologies, mechanical properties and adsorptive of human fibrinogen of the composite films were investigated. The HA nano-particles were dispersed in the films and well bonded to the polymer. The strength of films could be enhanced and its adsorptive of human fibrinogen could be also improved greatly by introducing HA nano-particles into the films. The results suggested these newly developed nano-HA/PHBV composite films might serve as an effective biomedicine material.

Abstract: The influence of the chemical modification on the electrical property of Si nanowire array was studied. It is found that H-terminated Si nanowire has a better electrical conductivity while OH-passivation could increase their resistance. It is believed that the introducing of OH group on the surface nanowire increases the interface traps and it is confirmed by our 1/f noise measurement.

Abstract: For analyzing the effect of different particles composing and distributing on composite propellant, it is necessary to generate mesh for the elliptical particles in composite propellant. A mesh automatic generation method is designed for the elliptical particles. This method is according to force-equilibrium mesh generation algorithm. And distance function and mesh size function is designed for the method. The program is in Matlab. The result shows that the method can automatically generate mesh and the mesh quality is good.

Abstract: This study presents experimental results of an approach consisting of local heating of aluminium alloy structures with the purpose of introducing a local change of material properties. Such modification can be precisely induced using a laser source, as detailed in this study. By a laser induced pre-treatment, the material properties are locally changed so that influencing the material flow is possible. It is therefore possible to improve deep drawing of high strength aluminium alloys. This technique can also be applied to thin-walled section aluminium tubes in order to act as local triggering of the deformation process reducing peak loads and inducing energy favourable folding modes. This study presents preliminary results of temperature, heating cycle and laser parameters influence in material properties and microstructure of a selected 6060-T5 aluminium alloy.

Abstract: The shape and size of the linked polymer microspheres and the matching between the microsphere size and nuclear-pore membranes were studied in this paper. Scanning electron microscopy(SEM), microscope, dynamic lighting scattering(DLS), Laser diffracting measurements, nuclear-pore film filtration and sand packed tube displacement experiment was adopted for investigation. The results showed that the original shape of the microspheres is typically spherical with a size range of 400-5000nm. When the microspheres were dispersed in water, swelling occurred, resulting in larger size but spherical conformation remained. And the system was poly-dispersed. There are certain matching relationships between the microsphere size and the membranes pore size, and the best plugging property could only occur when they are well-matched. Matching relationships also exist in the sand packed tube displacement experiment, when sand packed tubes with low permeability were used, plugging could occur effectively, and well in-depth plugging could happen as well.

Abstract: The amorphous FeCuNbSiB ribbons were first annealed at the temperature of 450 oC and 540 oC, respectively. Then, these annealed ribbons were milled into flake particles with the same condition. The different annealing temperature made the ribbons have the different crystallinities, which caused the milled particles have the different structures, morphologies, and magnetic properties. As for the flake particles by milling the ribbons annealed at 540 oC, they had higher crystallinity, smaller size, lower coercivity, and higher complex permeability compared with those by milling the annealed ribbons at 450 oC.

Abstract: An economical production process of higher N-acetylchitooligosaccharides [(GlcNAc)n, n=5~7 ] was developed with enzymatic and chemical reactions in this study. (GlcNAc)n were prepared selectively and efficiently by hydrolysis of chitosans with cheap enzyme preparations including cellulase TV, cellulosin A.C and hemicellulase, followed by N-acetylation with acetic anhydride. Higher (GlcNAc)n could be obtained in high yields by using cellulosin A.C and hemicellulase, which are originated from Aspergillus niger.

Abstract: Several crude enzymes including cellelase Tv, hemicellulase and lipase, papain as well as cellulase Ac were examined for the effective production of N-acetyl-D-glucosamine (GlcNAc) from amorphous α-chitin. Among the tested crude enzymes, cellulase Tv was found to be the most effective for directly degrading amorphous α-chitin to GlcNAc. High yield of GlcNAc was achieved by choosing the optimum hydrolytic conditions at pH 4.5 and 37°C. By gradually adding, in three tantamount cases, the amount of cellulase Tv to amorphous α-chitin, the yield of GlcNAc reach 55.0%.

Abstract: The curing reaction of diallyl orthophthalate(DAOP) resin, which was initiated by dicumyl peroxide(DCP), was studied by Fourier transform infrared spectroscopy(FTIR). Differential scanning calorimetry(DSC) was used to determine the curing behavior and kinetic parameters of dicumyl peroxide (DCP) / diallyl orthophthalate (DAOP) system. The results clarified that the curing reaction of DAOP resin could be initiated by DCP at 150-180°C and the reaction heat diffused slowly in curing process. The gel-temperature, curing temperature and thermal treatment temperature of the DCP(3%)/DAOP system were 145.46°C, 166.03°C and 173.83°C. The apparent activation energy, frequency factor and reaction order were 130.200kJ/mol, 5.231×1010 and 0.9455, respectively.

Abstract: The silicon-rich filtrate which was obtained from the desilication solution of potassium-rich rock was used as raw materials to prepare nanometer sillica and ultrasonic dispersion method was applied to the chemical precipitation process. A detailed study was carried out on the effect of filtrate concentration, surfactant dosage, reaction temperature, calcinations temperature, ultrasonic dispersion on size of silica nanoparticles. The basic properties and size of particles were characterized by means of FE-SEM, TEM, XRD, TGA and FTIR. The results obtained in the study indicated that monodisperse and uniform-size silica nanoparticles were prepared using ultrasonication by chemical precipitation process and the average particle size was 50 nm.