共查询到20条相似文献,搜索用时 171 毫秒
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涂层的传统固化方法是热固化,此种固化过程耗时长达数十小时,生产效率很低,电子束固化是以电子加速器产生的电子束(EB),对样品进行辐照,使其固化的过程,与热固化相比,它有许多优越性,如电子束固化涂料体系时,树脂不需要溶剂的稀释,产生挥发性有机物质少,环境污染小; 相似文献
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介绍了一种研究沸石结构的低剂量高分辨电子显微学方法,该方法可以有效降低电子束对沸石样品的辐照损伤,获得的高分辨像的分辨率优于0.18nm。提出了降低电子辐照损伤的措施,阐述了低剂量高分辨成像技术的技术要点。 相似文献
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从单层和少层的石墨烯出发,利用透射电子显微镜中的高能电子束辐照,可控地制备了准二维完全无定形和半无定形碳结构.用高分辨成像和相干的纳米区域电子衍射技术表征了样品结构在高能电子束辐照前后的变化.基于实验记录的电子衍射花样得到了样品的原子对分布函数.分析表明,在所制备的准二维无定形结构中,六元环不再是碳原子的主要排列方式,碳原子的各阶最近邻间距相对于完美石墨烯中的值有所偏离并趋向无序;同时还发现,锯齿型的碳链结构不易被破坏,并使得准二维无定形碳结构中还保留了短程有序和可达0.5nm的中程有序. 相似文献
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分别采用循环伏安改性法和恒电位氧化法对石墨毡进行改性处理,并采用循环伏安法对其电化学性能进行研究,实验结果表明,恒电位氧化改性较循环伏安改性的石墨毡有较好的氧还原活性。通过XRD、FTIR、接触角和CV针对恒电位氧化处理石墨毡进行了进一步的测试。测试结果显示,随恒电位氧化时间的增加,石墨毡表面亲水性含氧官能团增加,润湿性增强。恒电位氧化改性处理25 min的石墨毡氧还原峰电位及电流密度分别为~-0.43 V和~0.003 4 mA·cm-2,显示出很好的电化学催化性能。基于以上结果,恒电位氧化法改性处理能够极大提高石墨毡的氧阴极活性。 相似文献
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Bibo WangXiaofeng Wang Yongqian ShiGang Tang Qinbo TangLei Song Yuan Hu 《Radiation Physics and Chemistry》2012,81(3):308-315
Ethylene vinyl acetate copolymer (EVA) flame retarded by ammonium polyphosphate (APP) and pentaerythritol (PER) was cross-linked by electron beam irradiation. The effects of vinyl acetate content and electron beam irradiation on the flame retardancy, mechanical and thermal properties of EVA composites were investigated. The volatilized products of EVA/APP/PER composites were characterized by thermogravimetric analysis/infrared spectrometry. As VA content increased, the volatilized products increased in the second decomposition step, but decreased in the third decomposition step. For all samples, the increase of irradiation dose could improve both the gel content and the Limit Oxygen Index (LOI, the minimum oxygen concentration by volume for maintaining the burning of a material) values of irradiated composites. The mechanical and thermal properties of the irradiated EVA composites were also evidently improved at appropriate irradiation dose as compared with those of unirradiated EVA composites, whereas these properties decrease at higher irradiation dose because of the electron beam irradiation-induced oxidative degradation or chain scission. 相似文献
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Wei Huang Xiaoling Gao Jie Xiong Liangping Xiong Yunshu Xu Yibei Fu 《Macromolecular Symposia》2010,297(1):225-230
Summary: Two types of siloxane foam were irradiated by an electron beam at room temperature. Changes in the chemical structure of the samples were determined by Fourier-transform infrared resonance. The gaseous products from the irradiated samples were analyzed by gas chromatography and mass spectroscopy. Electron spin resonance was used to analyze the free radicals, and the compression properties were determined by a universal material tester. The results indicated that the effect of absorbed dose on the mechanical properties of polymethylvinyl siloxane foam was more pronounced than that for polymethylphenylvinyl siloxane foam. The yield of gases evolved from the radiation degradation of polymethylvinyl siloxane foam was higher than that from polymethylphenylvinyl siloxane foam. The free-radical signal from polymethylphenylvinyl siloxane foam was stronger and lasted longer than that from polymethylvinyl siloxane foam after irradiation. 相似文献
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Kyung-Hwa Kim Dong-Kyun Roh In Kyu Song Byung-Cheol Lee Sung-Hyeon Baeck 《Journal of Solid State Electrochemistry》2010,14(10):1801-1805
The influence of electron beam irradiation on the electrochemical properties of electrodeposited V2O5 thin films was investigated. V2O5 thin films were deposited electrochemically onto indium tin oxide-coated glass from an aqueous vanadyl sulfate hydrate (VOSO4⋅nH2O) solution using Pt and Ag/AgCl as the counter electrode and reference electrode, respectively. Electrodeposition was performed
potentiostatically at 1.7 V vs. Ag/AgCl. Electrodeposited samples were then subjected to a 1-MeV electron beam using an electron
beam accelerator at the Korea Atomic Energy Research Institute. For comparison, a control sample was not irradiated with the
electron beam. Crystallinity change before and after electron beam irradiation was investigated by X-ray diffraction and the
oxidation state of vanadium determined by X-ray photoelectron spectroscopy. Scanning electron microscopy was utilized to examine
surface morphology. It was observed that electron beam irradiation altered the oxidation state of vanadium and increased crystallinity.
Significant morphological changes of V2O5 thin films were also observed with electron beam irradiation. Cyclic voltammetry was employed to evaluate the electrochemical
properties of the synthesized V2O5 films in terms of their application as electrodes of lithium-ion battery. Compared with the control sample, which was not
irradiated with an electron beam, the electron beam-irradiated V2O5 specimens showed much higher capacitance. 相似文献
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《International Journal of Radiation Applications and Instrumentation. Part C. Radiation Physics and Chemistry》1989,33(1):47-50
The influence of irradiation with 5 MeV electrons on charge transport phenomena in the surface region of sintered ZnO was studied in the temperature range 200–600 K. Mobility and concentration of electrons were measured in the presence and absence of oxygen as a function of temperature both for irradiated and unirradiated samples. The influence of electron beam processing was found most pronounced for ZnO samples with absorbed oxygen. Radiation induced desorption of O2 was assumed to be responsible for enhanced effect of irradiation. Increased sensitivity of irradiated ZnO as an oxygen sensor has been observed and attributed to the formation of additional adsorption centres. A correlation between mobility of conduction electrons and their concentration in the surface region of irradiated ZnO with subsequently adsorbed oxygen was observed. 相似文献
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Zbigniew Zimek Grażyna Przybytniak Andrzej Nowicki 《Radiation Physics and Chemistry》2012,81(9):1398-1403
The computer simulations based on Monte Carlo (MC) method and the ModeCEB software were carried out in connection with electron beam (EB) radiation set-up for crosslinking of electric wire and cable insulation. The theoretical predictions for absorbed dose distribution in irradiated electric insulation induced by scanned EB were compared to the experimental results of irradiation that was carried out in the experimental set-up based on ILU 6 electron accelerator with electron energy 0.5–2.0 MeV.The computer simulation of the dose distributions in two-sided irradiation system by a scanned electron beam in multilayer circular objects was performed for various process parameters, namely electric wire and cable geometry (thickness of insulation layers and copper wire diameter), type of polymer insulation, electron energy, energy spread and geometry of electron beam, electric wire and cable layout in irradiation zone. The geometry of electron beam distribution in the irradiation zone was measured using CTA and PVC foil dosimeters for available electron energy range. The temperature rise of the irradiated electric wire and irradiation homogeneity were evaluated for different experimental conditions to optimize technological process parameters. The results of computer simulation are consistent with the experimental data of dose distribution evaluated by gel-fraction measurements. Such conformity indicates that ModeCEB computer simulation is reliable and sufficient for optimization absorbed dose distribution in the multi-layer circular objects irradiated with scanned electron beams. 相似文献
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Jin Jun Jo-Chun Kim Joong-Hyeok Shin Ki-Wan Lee Young Soon Baek 《Radiation Physics and Chemistry》2004,71(6):1095-1101
The effect of electron beam irradiation on the CO2 reforming of methane over Ni/Al2O3 was investigated. The conversion rate of CO2 and CH4 forming H2 and CO using various catalysts irradiated with an absorbed dose greater than 2 MGy was 5–10% higher than when using an untreated catalyst. The Ni/O ratio on the catalyst surface increased after treatment with an electron beam, and was more prominent for catalysts with a higher Ni content. As such, based on XRD and XPS measurements, electron beam treatment was found to result in either the desorption of oxygen from NiO or the removal of OH groups from the outermost surface layer of the catalyst. In addition, the concentration of active sites, such as Ni2+ and NiO, or surface defects was also found to increase with the absorbed radiation dose, thereby increasing the conversion rate. 相似文献
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Jiuqiang Li Jing Peng Jinliang Qiao Dongbin Jin Genshuan Wei 《Radiation Physics and Chemistry》2002,63(3-6):501-504
Two ethylene–octene copolymers (POE) were irradiated with 60Co gamma radiation and influence of irradiation atmosphere, absorbed dose and heat treatment of samples on the crosslinking were studied. Thermal properties and crystalline morphology of non-irradiated and irradiated POE were determined by using differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXS), respectively. The Charlesby–Pinner equation was used to describe the relationship between absorbed dose and sol fraction. The gel fraction of irradiated POE was lower and decreased with the increase of octene content when irradiated in oxygen, compared to irradiation in nitrogen atmosphere. The gel fraction increased significantly with the increasing of absorbed dose for the two copolymers. Heat treatment of samples prohibited the crosslinking of irradiated POE. The DSC results indicated that a subtle change of thermal properties of POE was observed before and after gamma irradiation at low dose. No change was found from the WAXS spectra of non-irradiated and irradiated POE. For heat-treating samples, the Charlesby–Pinner equation can not fit perfectly with the relationship between the sol fraction and absorbed dose, but it fits well with the crosslinking reaction of POE pellets. 相似文献
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V.T. Lazurik S.A. Pismenesky G.F. Popov D.V. Rudychev V.G. Rudychev 《Radiation Physics and Chemistry》2007,76(11-12):1787-1791
The features of absorbed dose field formation in objects irradiated with scanned X-ray beams at double—and four-sided irradiation were investigated both analytically and by Monte Carlo methods. An analytical approach uses an angular/spectrum X-ray characteristics calculated with PENELOPE, JEANT 4 and ModeXR codes. It was shown that the special angular orientation of electron beam incidence on the X-ray converter leads to X-ray dose smoothing on the surface of the irradiated object. At the same time, a double-sided irradiation can provide high X-ray beam efficiency at dose uniformity ration (DUR) <1.5 for sizeable object thickness. At four-sided irradiation, the angular orientation of electron beam incidence on the X-ray converter should be changed so as to focus the electrons to the center of the converter. At this mode X-ray beam efficiency is more than 60%. 相似文献
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Dried almonds, raisins, dates and pistachio were irradiated using either gamma radiation or electron beam, at an average absorbed dose of 5 kGy. To detect the previous irradiation different parts of the dried fruits were analyzed by ESR spectroscopy: almonds: skin; raisins: dried pulp; dates: dried pulp and stone; pistachio: nutshell. Analyses were carried out 2–3 months and 6 months after irradiation. A series of signals tentatively described as “cellulose-like”, “sugar-like” and “complex” radical were observed, and some slight differences between spectra from samples irradiated with gamma rays and electrons were evident. 相似文献
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Nakagawa K Ikota N Anzai K 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,69(5):1384-1387
We investigated the sucrose radical-production cross-section induced by heavy-ion irradiation. L-alanine was also used in order to compare radical yield and cross-section. The stable free radicals after irradiation were analyzed by electron paramagnetic resonance (EPR). The radical yield obtained by the irradiated samples had a logarithmic correlation with the LET (linear energy transfer). Quantitative EPR analyses showed that radical productions for sucrose and L-alanine vary both by different particle irradiation and the LET under the same absorbed dose. Furthermore, the cross-sections of radical productions for samples were calculated. Both cross-sections for C ions irradiation under LET 30 keV/microm at 50 Gy dose were approximately 3.0x10(-9) microm(2), taking account of the molecular areas of the samples. The values of the cross-sections imply that multiple ionizing particles involve producing stable radicals. 相似文献