Advanced Materials Research Vols. 774-776

Abstract: Polysaccharide from Panax japlcus var (PJVPs) was extracted with microwave-assisted (MAE). The effects of operating conditions, such as extraction time, ratio of water to raw material , and microwave power, on the extraction yield of PJVPs were studied through a Box-Behnken design (BBD). The optimum extraction conditions were as follows: extraction time 9.14 min, power 728.5 W and ratio of water to raw material 27.57ml/g. The yield of polysaccharide was 14.02 % based on the above mentioned conditions.

Abstract: In this work, a kind of conductive polymer-silver paste was used to fabricate carbon fabric composite frequency selective surfaces (FSS) with four-legged slot elements. Screen printing and 3D engraving process were carried out to coat the conductive polymer-silver paste onto the carbon fabric preform and sculpt composite panels into composite FSSs, respectively. Free space and finite element methods were carried out to measure and calculate the electromagnetic transmission characteristics of the composite FSS, respectively. The calculated results are in good agreement with the experimental data. The cascaded effect in double-layered FSS were investigated by finite element method and design of experiment technique (DOE).

Abstract: A series of cross-linking core-shell structured poly (n-butyl acrylate) /poly (methyl methacrylate-co-styrene) emulsion polymer were prepared by semi-batch seeded emulsion polymerization with pentaerythritol triacrylate (PETA) as a cross-linking agent. The emulsion polymers were characterized by Fourier transform infrared spectra (FTIR) and transmission electron microscope (TEM), respectively. The influences of cross-linking agent content on the water resistance and mechanical properties of the emulsion films were investigated. The films prepared by the emulsion polymer with the cross-linking agent exhibited excellent water resistance, and mechanical properties (tensile strength and flexility), resulting from the cross-linking structure of shell segments compared with that prepared without cross-linking agent. The film of the emulsion polymer with 1.0wt% cross-linking agent exhibited better comprehensive performance.

Abstract: This study developed a concise route to fabricate TiO₂ nanoporous and nanopillar films based on the self-assembly of block-copolymer thin films in periodic nanostructures. We obtained the perpendicularly oriented cylindrical domains in polystyrene-b-poly (methyl methacrylate) (PS-b-PMMA) diblock copolymer (BCP) films by thermal annealing on ITO substrate modified by a cross-linkable random copolymer, and then these films were immersed into the titanium oxide sol in acetic acid for a few hours. The acetic acid in the sol can selectively swell the PMMA component, which results in titanium oxide sol being loaded to the PMMA component selectively. Then the films were calcined at high temperature to remove the PS-b-PMMA block copolymer, and simultaneously the titanium oxide was transferred in situ to the substrate. As a result, a highly ordered array of nanoporous and nanopillar TiO₂ thin film is observed on the ITO substrates depending upon the block copolymer used with PS and PMMA cylinder-forming components. In principle, it can be a general and versatile approach for fabricating functional nanoparticle arrays.

Abstract: M-type Ba-hexaferrite (BaM) thin films with two different structures (single layered and double layered) were deposited on (001) Al₂O₃ substrates by RF magnetron sputtering. The changes in microstructural and magnetic properties of the films corresponding to different layer structures and substrate temperatures (T_s) were investigated. Experimental results indicated that for the single layered films deposited directly on substrates at T_s = 300 °C and T_s = 500 °C, most of the grains are acicular type grains with their c-axis in-plane and/or randomly oriented. However, in the double layered film with first interfacial layer deposited at T_s = 300 °C and second layer deposited at T_s = 500 °C, good crystallographic characteristics and excellent perpendicular c-axis orientation were obtained. The c-axis dispersion angle (Δθ_c) decreased to 0.49^°, while the squareness ratio and coercivity of the out-of-plane respectively increased to 0.85 and 4.67 kOe in the double layered film. The mechanism for improving perpendicular c-axis orientation with the interfacial BaM layer was attributed to an increase in the perpendicularly oriented nucleation sites and the release of the stress that comes from the film-substrate interface.

Abstract: To prepare concrete by applying industrial or agricultural wastes (energy saving materials) and natural lightweight aggregates, is a new pathway to develop lightweight aggregate concrete. The waste cornstalk, rubber particles made with industrial wastes, polyphenyl granules and natural pumice, as lightweight aggregates, are organically mixed with cement according to certain of proportion, so a kind of new multiphase composite lightweight aggregate concrete was prepared. The research results indicate that the raw materials after pretreatment can form good interfacial bonding with cements, improve further the performances of hardened concrete. The good workability, certain strength and low apparent density of concrete could be guaranteed.

Abstract: In this study, the local stress of unidirectional fiber reinforced marine composites under transverse direction tension is conducted by using a representative volume element (RVE). With the application of fracture mechanics theory, the strength and debonding evolution of the fibre-matrix interface is analyzed and simulated by cohesive elements in FEA. The modeling results fit the experimental results in quasi-static conditions well, which demonstrates a proper simulation method for assessing the transverse mechanical properties of marine composites. Considering the complex work environment in ocean, transverse mechanical behaviors of marine composites under different strain rates is investigated, which would provide guidance for the marine composite designers.

Abstract: KGM and Collagen II were selected as the main raw materials and ammonia served as the crosslinking agent to prepare the porous KGM / COLII composite cartilage scaffolds by blending method and freeze-drying method. The porosity, average pore size, compressive strength and water absorption were measured on the basis of the related standard. The scaffolds were characterized by SEM and XRD. The results show that the optimal program of preparing composite cartilage scaffolds is KGM (2g), COLII (1g), freeze temperature (-20 ° C) and ammonia (0.1 ml). The optimal cartilage scaffolds are porous three-dimensional network structures which the porosity is more than 90%; the average pore size is about 200μm; the compressive strength is about 0.75Mpa and the water absorption reaches up to 892%.

Abstract: The electrical properties need to be improved, although Aluminum doped ZnO thin films (ZnO: Al) have been successfully deposited on transparent TPT substrates by our group. In this paper, ZnO: Al film was deposited on TPT substrate with SiO₂ buffer layer by RF magnetron sputtering. The obtained film had a hexagonal structure and highly (002) preferred orientation. Compared with ZAO film without buffer layer, the lattice constant distortion of the film with buffer layer was decreased and the compressive stress was decreased by 9.2%, reaching to 0.779GPa. The carrier concentration and hall mobility of the film with buffer layer were both increased; especially the carrier concentration was enhanced by two orders of magnitude, reaching to 2.65×10⁺²⁰/cm³. The resistivity of ZAO film with SiO₂ buffer layer was about 7.6×10^-3 Ω·cm and the average transmittance was over 70% in the range of 450~900nm.

Abstract: Gemini surfactants are chemical compounds known as new generation of surfactants that their molecules has two hydrophilic groups ,two hydrophobic groups and a spacer.They have low CMC value and high surface activity.Gemini surfactants are inapproachable by any surfactants that are used for TOR nowadays.This essay is meant to solve the problems faced in the territory by using the remarkably high surface activity,introducing Gemini surfactants to TOR and launch series of experiments.Meanwhile,it provides technical and theoretical support for applying Gemini surfactants into the field.