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141.
Films of poly(vinyl butyral) composites with triphenyl tetrazolium chloride dye (TTC) and the antioxidant nickel dibutyl dithiocarbamate (NBC) or 2‐mercaptobenzimidazole (MBI) were prepared by the solution casting method using butyl alcohol as a solvent. The effect of various doses of electron beam irradiation (50–200 kGy) on color response, thermal, and mechanical properties were investigated. The color measurements showed that the films of the different composites possessed a high sensitivity to electron beam irradiation, in which the nearly colorless films were changed to deep red color, which can be easily detected by visual observations. In addition, the change in color depends on irradiation dose and the contents of the TTC dye. Moreover, the presence of the antioxidants NBC or MBI has no effect on the development of color. However, PVB/TTC and PVB/TTC/MBI composites showed high regular change in color as a function of irradiation dose. The thermogravimetric analysis used to study the thermal stability indicated that PVB/TTC composites either before or after electron beam irradiation are thermally more stable than neat PVB polymer. The presence of the antioxidants NBC or MBI offered protection to PVB/TTC composites against decomposition or oxidative degradation resulted from irradiation. Blending unirradiated PVB with TTC dye, mixture of TTC and NBC, and mixture of TTC and MBI reduced the tensile strength by 4, 20, and 17% upon blending, respectively. However, the reduction in tensile strength of the entire composite films (~7% based on the initial value) upon exposure to a dose of 50 kGy is acceptable for practical applications. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4358–4365, 2006 相似文献
142.
Chao Ye Qing Chang Penghui Lei Wenhui Dong Qing Peng 《Journal of the American Ceramic Society》2022,105(9):5921-5928
Ti3SiC2 samples were irradiated by a 6-MeV Si+ ion to a fluence of 2 1016 Si+ ions/cm2 at 300°C followed by annealing at 900°C for 5 h. A transmission electron microscope was used to characterize microstructural evolution. The phase of Ti3SiC2 transformed from the hexagonal close-packed (HCP) to a face-centered cubic structure after irradiation. Hexagonal screw dislocation networks were identified at the deepest position of the irradiated area, which are the products of dislocations reactions. After annealing, the irradiated region has reverted to the original HCP structure. High-density cavities and stacking faults were formed along the basal planes. In addition, ripplocations have been observed in the irradiated region in the Ti3SiC2 sample after annealing. Our insights into the formation processes and corresponding mechanisms of these defect structures might be helpful in the material design of advanced irradiation tolerance materials. 相似文献
143.
Magdy M. Senna Ateyat M. Yossef Fatma M. Hossam Abdel Wahab M. El‐Naggar 《应用聚合物科学杂志》2007,106(5):3273-3281
Foamy low‐density polyethylene/plasticized starch (LDPE/PLST) blends at different compositions were produced in the presence of azodicarbonamide (ACA) compound as foaming agent. The LDPE/PLST blends before and after electron beam irradiation were investigated in terms of mechanical properties, bulk density, and structure morphology. Moreover, the biodegradability of these materials was evaluated by the soil burial test for 2 months, in which the buried sheets were also examined by scanning electron microscopy (SEM). The results showed that the increase of PLST content from 24 to 30% was accompanied by a decrease in the yield and break stresses of 10 and 20% for the unirradiated blends without the foaming agent, respectively. Further decrease in these mechanical parameters was observed after the foaming process. The bulk density, void fraction, cell size measurements as well as the examination by SEM illustrate clearly the cell growth of the foam structure. The soil burial test and SEM micrographs indicate the growth of microorganisms overall the blend sheets and that the blend was completely damaged after two months of burying. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
144.
Dongjiang Yang Yao Xu Lei Zhang Shangru Zhai Dong Wu Yuhan Sun 《Journal of Coatings Technology and Research》2006,3(2):127-131
A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by 1H MAS NMR. For direct comparison purposes, an SiO2 coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N2 absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals. 相似文献
145.
146.
Photocatalytic behavior of TiO_2 and ZnO prepared with different methods under ultraviolet and visible light irradiation 总被引:1,自引:0,他引:1
IntroductionIn recent years photocatalytic oxidation hasreceived considerable attention as an alternativeremediation technology since the method offers anumber of advantages over conventionaltechnologies [1,2] Elimination o… 相似文献
147.
148.
Jose E. Herrera Ja Hun Kwak Jian Zhi Hu Yong Wang Charles H. F. Peden 《Topics in Catalysis》2006,39(3-4):245-255
The advantages of the atomic layer deposition (ALD) method for preparation of tungsten, vanadium, titanium, and molybdenum
oxide catalyst supported on mesoporous silica are discussed, with emphasis on the importance of synthesis conditions on dispersion,
structure and activity of the resulting materials. A suite of complementary techniques such as DRS-UV/Vis, BET, 1H-NMR, XRD, and TEM were used to study the structural properties of the supported metal oxides, and probe reactions such as
2-butanol dehydration and ethanol partial oxidation were used to demonstrate the potential advantages of the ALD-prepared
catalysts. Specifically, highly dispersed oxides of titanium, molybdenum, and tungsten oxide on mesoporous silica were synthesized
using the ALD method. It is also demonstrated that attainment of high dispersions of vanadium oxide on mesoporous silica requires
the presence of at least a single layer of titanium oxide due to the well-known poor interaction between vanadia and silica.
The highly dispersed catalysts prepared here by ALD methods exhibited superior catalytic performance relative to those prepared
using conventional incipient wetness impregnation. 相似文献
149.
Chunjie Wang Hanjun Tu Ranran Su Jie Gao B. V. King D. J. O'Connor Liqun Shi 《Journal of the American Ceramic Society》2021,104(1):593-603
Cr2AlC MAX phase thin films prepared by radio-frequency magnetron sputtering were irradiated at room temperature by 100 keV helium ions to a fluence of 1 × 1017 ions cm−2. The effects of thermal annealing on the structural and mechanical properties of the helium-irradiated Cr2AlC films as well as the helium release were investigated by grazing-incidence X-ray diffraction (GIXRD), Raman spectroscopy, and scanning electron microscope (SEM) in combination with nano-indentation and elastic recoil detection (ERD) analysis. The irradiation-induced structural damage in the Cr2AlC is significantly recovered by thermal annealing at temperatures around 600℃, attributed to high defect diffusivity. After annealing to 750℃, the hardness of irradiated films recovered almost completely, which is ascribes to both defect recombination and reformation of damaged chemical bonds. Substantial helium release occurring at this annealing temperature is closely related to the damage recovery due to helium irradiation. 相似文献
150.
The damage induced in 3C-SiC epilayers on a silicon wafer by 2.3-MeV Si ion irradiation for fluences of 1014, 1015, and 1016 cm−2, was studied by conventional and high-resolution transmission electron microscopy (TEM/HRTEM). The evolution of extended defects and lattice disorder is followed in both the 3C-SiC film and Si substrate as a function of ion fluence, with reference to previous FTIR spectroscopy data. The likelihood of athermal unfaulting of native stacking faults by point defect migration to the native stacking faults is discussed in relation to damage recovery. Threshold energy densities and irradiation doses for dislocation loop formation and amorphous phase transformation are deduced from the damage depth profile by nuclear collisions. The role of electronic excitations on the damage recovery at high fluence is also addressed for both SiC and Si. 相似文献