Advanced Materials Research Vols. 476-478

Abstract: Poly(lactic acid)(PLA)was end-capped by isophorone diisocyanate(IPDI) to get PLA-IPDI under the condition of temperature of 176°C and pressure of 0.090 MPa for 13 mins, and then the PLA-IPDI was chain-extended with different molecular weights polyethylene glycol (PEG)-400, PEG-600, PEG-800, PEG-4000 and PEG-6000 to produce a series of block copolymer PLA-IPDI-PEGs. when n(–OH)/n(–NCO)=1.5:1, the molecular weight of PLA-IPDI is maximum. All the copolymer PLA-IPDI-PEGs were characterized by GPC, FTIR, DSC and contact angle testing. The results show that the polymeric degree of PLA-IPDI-PEG-800 is the best and its molecular weight is the biggest. Tg of PLA-IPDI-PEG-800 is the lowest and its hydrophilicity is better than the others modification PLA-IPD-PEGs and pure PLA.

Abstract: Magnesium-based alkalis and the Chelants (tetra acetyl ethylene diamine (TAED), Sodium Citrate and Opal) for hydrogen peroxide bleaching of bamboo pulp were investigated in this paper. The results showed that the optimal conditions of hydrogen peroxide bleaching of bamboo pulp were as follows: H2O2 4%, Mg(OH)2:NaOH=25%, Sodium Citrate 1%, Opal 1.5%, TAED:H2O2=0.67, temperature 60°C, and time 90 minutes. Under the optimum conditions, the brightness of bamboo pulp can be enhanced from 41.2% ISO to 78.2% ISO, while the brightness of bleached pulp by using the Mg(OH)2-based alkalis was higher than by using NaOH as the alkali source. It can be seen that Sodium Citrate, Opal, and TAED activated H2O2 bleaching needed lower reaction temperature, shorter time, and got better brightness and alleviated environment pollution, compared with the conventional H2O2 bleaching of the same pulp.

Abstract: A biodegradable poly (glycerol-glycol-sebacate) terpolymer (PGGS) with different composition is prepared by a three-step method. The structure and properties of the PGGS terpolymers were characterized by means of attenuated total reflectance-Fourier transform infrared (ATR-FTIR), differential scanning calorimeter (DSC) and X-ray diffraction (XRD) methods. The experiment results indicate that the the composition of terpolymers have an obvious influence on the structure of PGGS terpolymers. The degradation rate increases with the increasing crosslink degree of PGGS.

Abstract: Based on three dimensional modeling software Solidworks, the physical model of 2MW wind turbine’s gear box is constructed and transferred into ADAMS, and then the virtual prototype model of the gearbox is established by adding constraint and load. According to the working state of the gearbox in different wind, the dynamic simulation is carried out, obtaining the revolution of the output shaft and mesh force of all gears. The simulation results compared with the theoretical values to verify the accuracy of the simulation.

Abstract: Cr_1-xAl_xN coatings with different aluminum content were deposited on K38G alloy by reactive magnetron sputtering method. Oxidation behaviors of these coatings were investigated at 1000°C in air+10 vol.% water vapor. The surface morphologies and the microstructure of the oxide scales were analyzed by SEM and XRD, respectively. The results showed that the oxidation of the Cr_1-xAl_xN coatings in the wet air also obeyed the parabolic law; however, compared to that in the dry air, existing of 10 vol. % water vapor increased the parabolic rate constants of the coatings. It was believed that the accelerating of the oxidation rates was owing to easily outwards diffusion of Cr through the looser and coarser oxide scales formed on the surface of the coatings when oxidized in wet air.

Abstract: Nata is widely used in food, cosmetics and so on. However dried Nata is insoluble in water. It is very important to increase the rehydration ratio of dried Nata. The effects of vacuum infusion on dried Nata rehydration ratio were investigated. When Nata was immersed in 0.8% of CMC solution by the ratio of 1:2 (m:V) and vacuum infused at -8×104Pa for 5h, and then dried at vacuum degree of 52Pa by vacuum freeze drying, the rehydration ratio of 115.57was obtained

Abstract: Recently some existing works have developed computing Join query technology over wireless sensor networks. But these techniques are static, and are only used in special application designated connection rate. In order to construct the data query method that suits environment, this paper proposes an optimization join query method that is applicable to limited bandwidth context. The dynamic join optimization problem in multi-hop wireless sensor network is resolved and a cost-based model is designed. This algorithm can predict the selectivity in advance, and can optimize the pairs of data streams. Experimental verification on standard data sets verified the effectiveness of the proposed method.

Abstract: A selectively yeast cell trapping and arraying method was presented, utilizing PDMS micropillar array combining with chemical adhesion. Yeast cells were trapped on the top of micropillar array while swept on the flat area for the pinning of liquid/surface contact line on the micropillars and moving on the flat surface. And the modification of poly-L-lysine on the yeast cells improved the immobilization of cells on the surface of PDMS surface. Both of simulation and experiment results shows that by adjusting the diameter of micropillars, the number of yeast cells on each pillars could be controlled. Single cell array was formed with a 8.3 μm micropillar array, and majority yeast numbers of 3,4,5 was got for the 13.7 μm、18.0 μm and 18.8 μm micropillar array.

Abstract: In the paper, preparation and properties of pullulan composite films were studied. Several kinds of materials (glass, iron, steel, propene polymer and polyvinyl chloride plates) were chosen for preparing films. The results showed that the steel plate was the most suitable material for preparing film. The tensile strength of pullulan film was significantly reduced when the drying temperature was higher than 50°C. The time of dissolution observably decreased, whereas water vapor permeability increased with increasing drying temperature. Pullulan film has higher tensile strength, better water barrier properties, shorter solubilization time and lower elongation at break than those of hydroxypropylmethylcellulose film, respectively. The composite film (Pullulan and hydroxypropylmethylcellulose) with weight ratio (1/2) has higher tensile strength, better water barrier properties, longer solubilization time than those of other ratios. Difference properties of films could be obtained in different weight ratio (Pullulan and hydroxypropylmethylcellulose).

Abstract: Efficiency is a critical performance for a high-power ultrasonic transducer composed of 1-3 piezocomposites and geometric parameters of the composites can influence the efficiency of the transducer. The effect of inter-rod responses in the composite matrix on the efficiency was experimentally investigated in this study. For analyses, four PZT4-epoxy composite ultrasonic transducers with various volume fractions and inter-rod spacing were fabricated in-house. The experimental results demonstrated that the inter-rod coupling of the 0.1-mm spacing could significantly degrade the efficiency of the composite probe at about 1.0 MHz resonance since the 0.1-mm spacing between PZT4 rods was so small as to cause a high interference. At the same volume fraction, the transducer engineer should take the inter-rod coupling into account for the design of the high-power ultrasonic transducer.