Advanced Materials Research Vols. 476-478

Abstract: Triangular mesh is one of the widely used digital representation modes in CAD and CAM. And the offset operation of planar polygon takes an important role in path planning of layer milling complicated surfaces represented by triangular mesh. A vertex classification based adjusting method is presented. It improves the performance of edge isometry based offset algorithm.

Abstract: In order to improve the effect of natural bamboo fibers degumming, the factors affecting the natural bamboo fibers separation effect in general alkali boiling conditions after the process of steam explosion were researched. The results showed that the degumming rate increased with the rise of steam explosion pressure and the pressure maintaining time. As the steam explosion was stronger, the degree of the fibers separation and softness were better. After steam explosion and alkali boiling united degumming method, the hemicelluloses and lignin content of the fibers decreased by 41.61% and 31.94%, while the cellulose content rose to 63.59%. The effect of steam explosion and alkali boiling united degumming method was better than single alkali boiling or steam explosion. The morphology of fibers became smooth and the fiber’s diameter reduced obviously.

Abstract: For case of pulling inhibition and stagnation of slab casters appeared in one continuous casting department of WISCO, Factors include stress of dummy bar systems, integrated frictional force , compression force and pulling speed control mode are analyzed to get the causes. The case was ultimately changed with countermeasures such as equipment optimizing and technology improving. The stability and productivity of continuous casting was improved obviously as long as more benefit being provided.

Abstract: Spinel Zn₂SnO₄ photocatalysts have been prepared by the solid state reaction. as-prepared samples were characterized by power X-ray diffraction, scanning electron microscope, UV-vis diffuse reflectance spectroscopy and photocatalytic activity measurement. The results show that the reaction temperature have significant effects on the Zn₂SnO₄ photocatalytic activity . It has also been found that the distribution of the cations in Zn₂SnO₄ crystal lattice changes with the increase of calcination temperature, causing the local structural fine adjustment that associated with the photocatalytic properties.

Abstract: Heat treatment is an environmental method of wood modification. The density of Populus ussuriensis, dimensional change and equilibrium moisture content change were tested through the different temperature processing, and get the influence of heat treatment process on the performance of the wood. The results show that heat treatment is an effective way to improve wood dimensional stability and shrinkage properties. With the improvement of heat treatment intensity, the equilibrium balance moisture content of wood will then gradually reduced. When treating temperature reaches 180°C above, the wood drying shrinkage properties greatly decreased, and trend to stable.

Abstract: School climate affects students’ learning and many aspects of their life. The main purpose of the study is using fuzzy statistical analysis to investigate the membership and the fuzzy expected values of middle school students’ perception on school climate. And using fuzzy χ2-test of homogeneity analyzed different perception between different genders on school climate. The scale had six items and it designed by the researcher. The participants were 67 middle school students. They were asked to answer it by using fuzzy number. The findings were as follows. 1. Most students agreed that their school climate was good. They thought that school was a safe place, the communicative tunnels between school and students were appropriated, the teachers of school won their trust, and they felt satisfied with the school environment. 2. There were significant differences between different genders perception on school climate, like teaching quality, the policies of school could keep on doing them, and being satisfied with the school environment. The result can make the school understand more about students’ perception on school climate, and try hard to improve or maintain it. And it also makes us know better about the advantages of fuzzy statistical analysis.

Abstract: Dissolution and homogeneous graft copolymerization of cellulose were performed in an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) with L-lactide. The best synthetic condition of the cellulose-graft-poly (L-) (cellulose-g-PLLA) was that cellulose 0.6g, L-lactide 5.34g and 4-dimethylaminopyri lactide dine (DMAP) as an organic catalyst 0.69g reacted for 12 hours at 80°C. The synthesized AmimCl and cellulose graft copolymers were characterized by FT-IR, 1H-NMR, GPC, TG and WAXD. The results indicated that AmimCl dissolved cellulose directly by destroying intermolecular and intramolecular hydrogen bonds in cellulose and the grafting rate of the polymer reached 4.44, which was higher than that reported in AmimCl with Sn(oct)2 as a catalyst.

Abstract: In order to improve the toughness and impact resistance of PLA, nano-ZnO modified with different surface treatment agents (titanium ester, silane coupling agent and alkylamine) was added to PLA matrix. The samples were examined by fourier transform infrared (FT-IR) spectroscopy, micropolariscopy and mechanical properties. The results show that when the addition of nano-ZnO reaches to 0.2 wt.%, the tensile strength and elongation at break of PLA/ZnO nanocomposites have the maximum values of 20.5MPa and 10.2%, respectively. The mechanical properties of PLA/ZnO nanocomposites can be improved apparently modified with different treatment agents, and the spherocrystal size of the samples can be reduced obviously. Infrared spectra of nano-ZnO modified with different treatment agents include two peaks at 2919 cm-1 and 2851 cm-1, which are corresponding to C-H stretching vibration.

Abstract: To understand the fundamental mechanical properties of lotus fiber could provide theoretical basis for developing lotus fiber fabric. This paper is focused on the mechanical properties of lotus fiber under the state of wet, dry and normal temperature, which include the single tensile properties, the repeated tensile stress properties under constant elongation, stress relaxation and creep properties, and have comparation and analysis on the cotton fiber and the viscose fiber. The conclusion shows that the lotus fiber and viscose fiber are more effect by humidity than the cotton fiber. The fibre strength of lotus fiber was the biggest than cotton fiber and viscose fiber under the normal temperature and dry state. The elongation at break of viscose fiber was the biggest than lotus fiber and cotton fiber under the state of wet, dry and normal temperature. From wet state to normal temperature state to dry state, the fiber strength of lotus fiber increase gradually, and elongation at break gradually decreased. The plastic deformation resistance ability, the stress relaxation and creep properties of bamboo pulp fiber under wet state are best, and the dry condition are the worst.

Abstract: Nano-ZnO powder were prepared through gel-sol method with zinc acetate and lithium hydroxide as crude material. Nano-ZnO was analyzed by XRD, SEM, TEM, UV-Vis and determined photocatalytic activity at photocatalytic reactor. The results show that nano-ZnO has a integrate crystal and its size is 6.6nm with the best photocatalytic performance, when calcined at 350oC. The best ZnO dosage is 0.1g/L with 97% Methylene Blue removal after 30min. Compared with different photocatalytic reactor, the airlift reactor is obviously better than bubbling reactor and stirring reactor.