Advanced Materials Research Vol. 658

Abstract: This paper describes the test results on the direct shear behavior of glass-fiber reinforced polymer (GFRP) shear tie reinforced interfaces between precast concrete sandwich panels (PCSP) and extruded polystyrene (XPS) insulations. The insulated PCSP consists of two concrete panels with 100mm or 80mm thick insulation between inner/outer concrete panel layers. In order to achieve composite action concrete panels are connected by corrugated GFRP shear connector. In this study, three types of couple replicate insulated PCSP with different embedment length of GFRP shear connector were made and loaded in push-out. The test results indicated that the reinforcement of GFRP shear ties for interface between PCSP and XPS insulation improves initial and post-peak shear performance of insulated PCSPs. These phenomena are remarkable for XPS insulated PCSPs with larger embedment length of GFRP shear connectors.

Abstract: The implementation of nanotechnology in concrete has led to an active incorporation of nano silica in concrete in a global level. Different methods of nano silica production are available and vary from expensive to cost-effective routes. Nano silica particle sizes and their chemical and physical nature depend on the method of production. Several types of dispersed nano silica are recommended to be used in concrete due to practical reason. However, the dry powders of nano silica particles are difficult to be dispersed in concrete and require special types or family of nano superplasticizers. The effective addition of nS leads to C-S-H with improved cementitious properties.

Abstract: In this paper, the linear low density polyethylene (LLDPE) was melted and cross-linked by dicumyl peroxide (DCP) used to prepare cross-linked polyethylene (XPE). The gel content was determined by extraction method. The effect of content of cross-linker, cross- linked time, cross-linked temperature and other factors on the gel content were studied. It was found that the extraction time should be 18h for XPE. The gel content increased with the increasing of cross-linked time. When the cross-linked time was 10-15min, DCP was almost complete decomposition. The gel content was basically stable when the cross-linked temperature was 170-175 oC. The maximum of gel fraction was about 90%.

Abstract: In order to prepare bioactive hydroxyapatite (Ca10 (PO4)6(OH) 2, HA) coating with ideal biocompatibility, the surface of titanium alloy was treated with the two kinds of chemical methods, which are the acid-alkali-combination method and Self-polymerization-adhesion of dopamine. After pretreatment, the treated titanium alloy plates were immersed in simulated body fluid (SBF) to form HA coating on their surface. The chemical composition of the coating was analyzed by an X-ray diffraction (XRD) and the morphology was observed by a scanning electron microscope (SEM). After that, the plates were training in vitro cytotoxicity test with MC3T3-E1 osteoblasts. Compared with the results of cell culture, the method of Self- polymerization -adhesion of dopamine showed better cell adhesion and proliferation..

Abstract: Objective: To investigate the microstructures and mechanical characteristics of enamel and dentin of primary and permanent teeth by AFM, analyze their relationships and provide information for bionics and designs of dental materials. Methods: After embedding, cutting and grinding, 10 primary teeth and 10 permanent teeth were randomly divided into four groups. The morphology of samples was obtained by AFM and the roughness and Young’s modulus were calculated by JPK DP Data processing version 4.0 software. Results: In permanent teeth groups, the enamel rods arrange more tightly than those in primary teeth groups. The roughness of primary enamel （1203±39.5nm）was higher than permanent teeth（954.6±30.5nm）.The Young′s modulus of enamel in primary teeth（80.4±7.7GPa）was lower than permanent teeth（90.8±2.2GPa）. The roughness of dentin in primary teeth （1695±67.6nm）is higher than permanent teeth （1210±45.3nm）and the Young′s modulus of dentin in primary teeth（19.8±1.9 GPa）was lower than the permanent teeth （23.1±1.0 GPa）. Conclusions: The mechanical characteristics of primary and permanent teeth are closely related to their microstructures.

Abstract: The objective was to investigate the corrosion resistance performance of Ti-6Al-4V alloy surface containing fluorine polymer film and polymer film to cell toxicity. Be evaluating the application prospect in modified method of medical titanium alloy. Using spin coating technique and thermal cross-linking method to prepare fluorine polymer film on Ti-6Al-4V alloy surface, and then characterized by XPS and surface contact angle. By electrochemical corrosion method and the cytotoxicity experiment were to evaluate corrosion resistance and cytotoxicity of the fluorine polymer film. The results show the XPS of the experimental group were stronger spectrum peaks of element C, F; but the spectrum peaks of element Ti, Al were not observed, the surface contact angle in experimental group increased from 57.7° to 97.1°, compared with the control group. The results of electrochemical corrosion experiment showed that the corrosion potential increased from -0.82 V to -0.062 V, and the corrosion current density of the experimental group reduced from 1.301 × 10-5 A • cm-2 to 1.939 × 10-7 A • cm-2, compared with Ti-6Al-4V alloy. Meanwhile the cytotoxicity test showed that RGR values of the experimental group were greater than 90% at different time points, and RGR values were higher than 100% at 2 and 4 days. In conclusion, the Ti-6Al-4V alloy surface with the preparation of fluorine polymer film has better corrosion resistance and no cell toxicity. It has well prospect in clinical application.

Abstract: The poor wetting property between aramid fiber and resin results in the low interfacial performance due to the inertia and smooth surface of aramid. 60Co gamma-ray was used to modify the surface of domestic aramid fiber in the medium of epoxy chloropropane and diethanolamine respectively. The properties of aramid/epoxy composites were characterized by interface shear strength (IFSS) and the effect of two graft polymerization systems on fiber surface was discussed. The results showed that in an irradiation dose of 400kGy, when chloropropane and diethanolamine were used respectively as the graft system, the IFSS value of the composite material reached 86.53MPa and 70.37MPa, and compared with the untreated sample, each increase of 31.23% and 6.72%. High-energy radiation treatment increased the surface energy of aramid. The original smooth surface was disappeared. Oxygen content on fiber surface greatly risen, and aramid surface activity increased.

Abstract: The physical properties and mechanical behavior of cement mortars containing waste tire rubber particles (WTRP) were studied. Several mortar mixtures were prepared by replacing quartz sand with 100% of WTRP and by using cement content of 150, 200, 250, 300, 350 and 400 kg/m3 respectively. Results indicated that dry bulk densities of the mortars containing WTRP were all less than 1000 kg/m3. The mortars had a certain hydrophobic property. The 28 d compressive strengths of the mortars were 0.59~2.29 MPa and the thermal conductivity values were 0.096~0.152 W/(m.K) increased with the cement content increasing. So, the mortars containing WTRP can be used as thermal insulating material.

Abstract: In this paper, for the purpose of ultrasonic signal compression and the coherent noise depressing in nondestructive test of aluminum alloy forging, the mathematical model of defect echoes is discussed and confirmed. And then the wavelet kernel is also confirmed according the waveform of the defect echoes. As the algorithms of standard hard thresholding and soft thresholding of wavelet transform can not bring out effective compression and depression to the coherent noise, an adaptive wavelet thresholding algorithm is introduced. Experimental results indicate that the adaptive wavelet thresholding algorithm can offer effective signal compression and depression to the coherent noise.

Abstract: The 3-D microstructure can be formed by using Multi-film thickness mask (MFT-mask) with single exposure and single develop. The intensity of the UV light getting through the mask increases as the thickness of the chromium film decreases. However, the ultra-thin Cr film makes the deposition and etching process of Cr film difficult to control. By depositing the nickel film as a buffer layer on the Cr film, the Cr/Ni film stack can filter the UV light and increase the amount step of the light intensity. This can improve the performance of the MFT-mask to generate fine 3-D patterning step similar to gray-scale lithography with lower cost.