电子束辐照对HDPE结构与亲水性能影响的研究

研究了在空气中电子束辐照所引起的ＨＤＰＥ分子结构变化以及辐照对ＨＤＰＥ亲水性的影响”。结果表明,通过电子束辐照可在ＨＤＰＥ分子链上引入含氧极性基团,使的表面自由能增大,极性增强,与水的接触角减小。辐照ＨＤＰＥ的分子量降低,分子量分布变窄。     

电子束预辐照聚乙烯醇纤维接枝丙烯酰胺的研究

以较高强度较高模量的聚乙烯醇纤维为接枝基体,丙烯酰胺为接枝单体,研究了高能电子束预辐照接枝反应的主要影响因素及接枝后纤维的力学性能变化,并对接枝机理进行了初步探讨。     

电子束和γ射线对油料氧化及霉菌的影响

目的探讨电子束和γ射线等2种射线对油料脂肪氧化及霉菌含量的影响。方法以花生、芝麻、大豆为原料,采用1,3,5,7,9 kGy的辐照剂量对样品进行辐照处理,分析不同射线和不同剂量处理对原料含油率、酸价、过氧化值和霉菌总数的影响。结果辐照对油料含油率基本无影响;2种射线辐照均能有效地降低花生、芝麻和大豆的酸价,而且变化规律相似,在电子束辐照剂量为5 kGy下花生、芝麻和大豆的酸价最低,分别降低了54.29%,37.50%,37.33%。γ射线辐照对花生和芝麻的酸价的下降幅度大于电子束辐照,而大豆的情况则相反;2种射线辐照对花生过氧化值的影响不大,但γ射线辐照的过氧化值整体上略低于电子束辐照;2种射线辐照在一定程度上增加了芝麻的过氧化值;大豆的过氧化值随着2种射线辐照剂量的增加而降低,在1～5 kGy剂量下,γ射线辐照降低大豆的过氧化值的幅度整体低于电子束辐照。辐照能有效地杀灭油料中的霉菌,且辐照剂量越大其杀菌效果越好。相比而言,γ射线辐照对油料的霉菌杀灭效果好于电子束辐照。结论 2种射线在3 kGy辐照剂量下对油料质量无显著的负面影响,可作为油料防虫和防霉的适宜剂量。     

电子束辐照对尼龙66纤维结构和力学性能的影响

研究了室温空气条件下电子束辐照剂量(范围0~1000 k Gy)对尼龙66纤维结构和力学性能的影响。利用广角X射线衍射仪、差示扫描量热仪、扫描电镜以及YG065型织物强力仪等测试方法研究了不同辐照剂量尼龙66的特性黏数、晶型结构、取向度、结晶和熔融行为,以及表面形貌和力学性能。研究结果表明,在设置的辐照剂量范围内,随着剂量的增加,纤维原有的晶型结构不变,但是,伴随辐照诱导非晶区分子链的重排,纤维的结晶度提高,取向有所改善,而结晶和熔融温度向低温偏移,熔融峰出现宽化。说明辐照主要导致尼龙66分子链氧化降解,降低其热稳定性,在电子束的撞击下,纤维表面产生了微裂纹,增加了应力集中,破坏了纤维的力学性能。     

电子束辐照对碳纳米管结构及性能的影响

对近年来电子束辐照碳纳米管(CNTs)的研究进展进行了评述,重点阐述了电子束辐照对CNTs的结构缺陷、管径、力学性能、电性能和场发射性能的影响,探讨了电子束辐照技术在CNTs切割和焊接方面的独特优势,并对辐照温度和入射电子能等条件对CNTs辐照效果的影响进行了分析。可以预期,采用电子束辐照处理CNTs仍将是未来一段时间研究的热点之一。     

电子束辐照对UNMWPE树脂结构和力学性能的影响

研究了电子束辐照超高分子量聚乙烯(UHMWPE)树脂的交联现象,探讨了不同电子束辐照吸收剂量对UHMW-PE的微观结构、力学性能和溶胀度的影响。结果表明,辐照UHMWPE的最大拉伸强度、结晶度和交联度都随着吸收剂量的增大先增大后减小,分别在10kGy、50kGy和100kGy时达到最大值47.3MPa、54.4%和1.66×10-4mol/cm3;溶胀度(SR)和交联网链平均分子量(Mc)随吸收剂量增大先减小后变大;断裂伸长率随吸收剂量的增加而变小。     

电子束辐照对氧化锌纳米线I-V特性的影响

在扫描电镜中,采用纳米微操纵仪构成一个2探针电流-电压（I-V）测试装置。测试了单根ZnO纳米线接触钨电极构成的金属-半导体-金属（M-S-M）结的I-V特征曲线。ZnO纳米线的I-V曲线呈现出较弱的肖特基特性。研究了电子束辐照对ZnO纳米线的I-V曲线的影响。30 keV电子束辐照使ZnO纳米线的总电阻减小。计算得到ZnO纳米线的电导率σ=0.24S/cm,载流子浓度n=1.64×10^16cm^-3。为了对比,还测试了单根碳纤维接触钨电极的I-V特征曲线。在30 keV电子束辐照下,碳纤维的总电阻保持不变,电导率σ=22 S/cm。     

电子束辐照对BBO晶体一阶超极化率的影响

与传统热力学方法不同,本文从辐照电场角度出发研究电子束辐照对BBO(β-BaB2O4)材料的非线性性能影响。利用量子化学方法和有限场方法计算其一阶超极化率β的全部分量,以此分析不同辐照强度下β的改变规律。研究表明:在电子束流强度为50μA的情况下,当射线能量小于400Mev时辐照电场对β的影响不大,平均值βav波动幅度最大仅为3%;此后随射线能量增大βav开始急剧下降,能量越高下降速度越快,420Mev时已经下降10%,材料面临失效的危险。研究结果还表明辐照电场对β三个分量的影响并不一致,随辐照能量增加βx、βy分量呈减小趋势,但βz分量却增加较快,预示着晶体中的共扼π轨道可能受到破坏。     

电子束辐照对氧化锌纳米线Ⅰ-Ⅴ特性的影响

在扫描电镜中,采用纳米微操纵仪构成一个2探针电流-电压(I-V)测试装置.测试了单根ZnO纳米线接触钨电极构成的金属-半导体-金属(M-S-M)结的I-V特征曲线.ZnO纳米线的I-V曲线呈现出较弱的肖特基特性.研究了电子束辐照对ZnO纳米线的I-V曲线的影响.30 keV电子束辐照使ZnO纳米线的总电阻减小.计算得到ZnO纳米线的电导率σ=0.24 S/cm,载流子浓度n=1.64×1016 cm-3.为了对比,还测试了单根碳纤维接触钨电极的I-V特征曲线.在30 keV电子束辐照下,碳纤维的总电阻保持不变,电导率σ＝22 S/cm.     

Theoretical study on influence of electron beam irradiation on the first-order hyperpolarizability of BBO crystals

A mechanism not based on the traditional thermodynamics effect but on the microscopic origin of the nonlinear effect was investigated for full consideration of the correlation between the e-beam irradiation electric field (IEF) and the properties of the nonlinear material BBO (β-BaB₂O₄). Firstly, the IEF magnitude is computed under different conditions of beam intensity, ray energy and radiation dose. Secondly, the relationship model of IEF and nonlinear coefficients is built according to quantum mechanics principle. The results show that low-energy irradiation of 0–400?MeV ray energy (corresponding to IEFs of 0–12?×?10^?4?a.u.) has no obvious effect on the nonlinear optical properties of BBO crystals. When the energy is higher than 420?MeV (corresponding to an IEF of 13?×?10^?4?a.u.), the hyperpolarizability changed significantly, indicating permanent damage of the BBO crystals. With an increase of the ray energy, βx and βy tend to decrease, but βz increases markedly especially when the ray energy is more than 450?MeV (corresponding to an IEF of 16?×?10^?4?a.u.).     

Effect of gamma irradiation and silver doping on YBCO superconductor

The effect of -irradiation and silver doping on the properties of YBCO superconductors has been studied by electrical resistance measurements and x-ray diffraction techniques. The zero-resistance superconducting transition temperature of (YBCO)_1–xAg _x systematically increase by about 2 K with an increase of Ag content up tox=0.04. Further increase in Ag content decreases the transition temperature. The normal-state resistance decreases up to a factor of 3.4 with an increase of Ag content. No significant change in the transition width has been observed due to silver addition up tox=0.30. Undoped YBCO and the Ag-doped specimens of (YBCO)_1.96Ag_0.04 were irradiated with-rays up to an integrated-dose of 77 MR. The normal-state resistance of the specimens gradually increases and the transition temperature slightly decreases with increase of-dose. The intensities of the x-ray diffraction peaks of the monolayers of the sample powders decrease with -irradiation without noticeable change of diffraction angles or peak widths. These observations indicate that the high-T _c supconductor YBCO is quite sensitive to-irradiation but drastic lattice expansion does not occur up to a-dose of 77 MR.     

Effects of electron beam irradiation on tin dioxide gas sensors

In this paper, the effects of electron beam irradiation on the gas sensing performance of tin dioxide thin films toward H₂ are studied. The tin dioxide thin films were prepared by ultrasonic spray pyrolysis. The results show that the sensitivity increased after electron beam irradiation. The electron beam irradiation effects on tin dioxide thin films were simulated and the mechanism was discussed.     

Studies on certain wood-plastic-composites prepared by gamma irradiation

Wood-plastic-composites have been prepared using locally available soft wood and commercial monomers by vacuum impregnation of monomer in wood and subsequent polymerization by gamma irradiation. The irradiation was performed by means of a⁶⁰Co source of strength 50,000 Ci at 0·2 Mrad/h. The radiation dosage required for maximum conversion of monomer into polymer was less than 2 Mrad except styrene which required a much larger dose of about 10 Mrad. The impregnation efficiency was found to be more for wood with high pore volume. The impregnation efficiency also depended on the ambient pressure: the more the vacuum, the more was the impregnation efficiency. Mechanical strength of the composites was found to be enhanced and water absorption considerably reduced. X-ray diffraction studies showed that the crystallinity of the cellulose did not get affected by the radiation polymerization which suggested that grafting of polymer on to the cell wall took place only in the amorphous regions.     

Effects of electron beam irradiation on commercial polypropylene: Kinetic study of antioxidant degradation

The long-term influence of electron beam irradiation on food packaging materials (OPP) was studied. After irradiating the material at dose levels of 2, 5 and 10 kGy, we have shown a partial or complete disappearance of the antioxidant (Irganox 1010 and Irgafos 168) over time and a release of five new compounds resulting from antioxidant degradation. All of these degradation compounds have been identified and quantitatively analysed in relation to post-irradiation time and absorbed dose. These results allow an explanation of the antioxidants' behaviour during storage of the irradiated polypropylene at room temperature.     

Effects of gamma irradiation for sterilization on aqueous dispersions of length sorted carbon nanotubes

There is currently great interest in the potential use of carbon nanotubes as delivery vessels for nanotherapeutics and other medical applications. However, no data are available on the effects of sterilization methods on the properties of nanotube dispersions, the form in which most medical applications will be processed. Here we show the effects of gamma irradiation from a ⁶⁰Co source on the dispersion and optical properties of single-wall carbon nanotubes in aqueous dispersion. Samples of different length-refined populations were sealed in ampoules and exposed to a dose of approximately 28 kGy, a level sufficient to ensure sterility of the dispersions. In contrast to literature results for solid-phase nanotube samples, the effects of gamma irradiation on the dispersion and optical properties of the nanotube samples were found to be minimal. Based on these results, gamma irradiation appears sufficiently non-destructive to be industrially useful for the sterilization of nanotube dispersions.     

电子束照射下钼纳米微粒的形成

使用高分辨透射电子显微镜在室温台上通过电子束照射ＭｏＯ３，制备钼及钼的亚氧化物钠米微粒，实验发现微米级ＭｏＯ３颗粒强度为１０＾２１ｅ／ｃｍ＾２．ｓ的电子束照射下转变为纳米级亚氧化钼，经过电子束的进一步照射后，亚氧化钼转变为钼。这种现象可能是由于电子束的激发作用和通过撞击效应而使原子发生错排引起氧原子分离造成的。     

Comparison of radiation damage in lead tungstate crystals under pion and gamma irradiation

Studies of the radiation hardness of lead tungstate crystals produced by the Bogoroditsk Techno-Chemical Plant in Russia and the Shanghai Institute of Ceramics in China have been carried out at IHEP, Protvino. The crystals were irradiated by a 40 GeV pion beam. After full recovery, the same crystals were irradiated using a ¹³⁷Cs γ-ray source. The dose rate profiles along the crystal length were observed to be quite similar. We compare the effects of the two types of radiation on the crystal's light output.     

Preparation of PbSe nanoparticles by electron beam irradiation method

A novel method has been developed by electron beam irradiation to prepare PbSe nanoparticles. 2 MeV 10mA GJ-2-II electronic accelerator was used as radiation source. Nanocrystalline PbSe was prepared rapidly at room temperature under atmospheric pressure without any kind of toxic reagents. The structure and morphology of prepared PbSe nanoparticles were analysed by X-ray diffraction, transmission electron microscope and atomic force microscope. The results indicated that the obtained materials were cubic nanocrystalline PbSe with an average grain size of 30 nm. The optical properties of prepared PbSe nanocrystalline were characterized by using photoluminescence spectroscopy. The possible mechanism of the PbSe grain growth by electron beam irradiation method is proposed.     

Effects of electron irradiation on SiGe devices

The degradation and the recovery behavior of the device performance for SiGe diodes and p-MOSFETs irradiated by 2-MeV electrons are reported. For diodes, it is noted that both the reverse and forward current increase by irradiation. An interesting observation is that the forward current decreases after irradiation for a forward voltage larger than ~ 0.7 V. This reduction can be explained by an increased resistivity of the Si substrate. The degradation recovers by thermal annealing after irradiation. For a fluence of 1 × 10¹⁵ e/cm², the diode performance almost recovers to the initial condition after 250 °C annealing. For the transistors, after irradiation, a slight negative shift of the threshold voltage and a decrease of the drain current for input and output characteristics have been observed together with a decrease of hole mobility. This is mainly due to the increase of the threshold voltage induced by positive charge trapping in the gate oxide.