Application of radiation chemistry to the construction of functional organic materials

Although radiation-chemical reactions have been applied to many industrial fields, especially to polymer in-dustries, they are mainly aimed at improving mechanical, thermal and surface properties of the materials. Applica-tion of radiation chemical reactions to the construction of functional organic materials, such as electronic and op-tical materials, is relatively few. However, radiation-chemical reactions have the following characteristics that areadvantageous for studying and constructing …     

The Erosion and Erosion Products of Tungsten and Carbon Based Materials Bombarded by High Energy Pulse Electron Beam

High Z and low Z materials are both the candidate plasma facing materials (PFM), up to now, the typical representative of high Z materials is tungsten, and the representatives of low Z materials are carbon materials (such as graphite, C/C composite) and beryllium. Most of these materials have been used as PFM limiters     

Applications of Skyrme Energy-Density Functional to Fusion Reactions for Synthesis of Superheavy Nuclei

The Skyrme energy-density functional approach has been extended to study the massive heavy ion fusion reactions. Based on the fusion barrier obtained and the parameterized barrier distribution the fusion （capture） excitation functions of a lot of heavy-ion fusion reactions are studied systematically.     

PROGRESS ON THE EVALUATION OF CHARGED PARTICLE NUCLEAR REACTION DATA IN SICHUAN UNIVERSITY

According to the assignment of the secord meeting on CPND(Xian,1989),the evaluations of excitation functions of 9 reactions induced by charged par-ticles have been fulfilled.The evaluated nuclear reactions and the experimentalworks are listed in table 1.     

Kinetic Migration of Diethylhexyl Phthalate in Functional PVC Films

Plasticizers that are generally used in plastics to produce flexible food packaging materials have proved to cause reproductive system problems and women’s infertility.A longterm consumption may even cause cancer diseases.Hence a nano-scale layer,named as functional barrier layer,was deposited on the plastic surface to prevent plasticizer diethylhexyl phthalate’s(DEHP) migration from plastics to foods.The feasibility of functional barrier layer i.e.SiO x coating through plasma enhanced chemical vapor deposition(PECVD) process was then described in this paper.We used Fourier transform infrared spectroscopy(FTIR) to analyze the chemical composition of coatings,scanning electron microscope(SEM) to explore the topography of the coating surfaces,surface profilemeter to measure thickness of coatings,and high-performance liquid chromatography(HPLC) to evaluate the barrier properties of coatings.The results have clearly shown that the coatings can perfectly block the migration of the DEHP from plastics to their containers.It is also concluded that process parameters significantly influence the block efficiency of the coatings.When the deposition conditions of SiO x coatings were optimized,i.e.50 W of the discharge power,4:1 of ratio of O 2:HMDSO,and ca.100 nm thickness of SiO x,71.2% of the DEHP was effectively blocked.     

Applications of Skyrme Energy-Density Functional to Fusion Reactions for Synthesis of Superheavy Nuclei

It is of great importance to predict fusion cross sections and to analyze reaction mechanism for massive heavy-ion fusion reactions, especially for fusion reactions leading to superheavy nuclei. In those reactions, the calculation of the capture cross section is of crucial importance. It is known that Wong＇s formula based on one-dimensional barrier penetration can describe the fusion excitation function well for light reaction systems, while it fails to give satisfying results for heavy reaction systems at energies near and below the barrier. For solving this problem, we applied the Skyrme energy-density functional for the first time to study heavy-ion fusion reactions. The barrier for fusion reaction was calculated by the Skyrme energy-density functional together with the semi-classical extended Thomas-Fermi method.     

Recent progress and perspective on batteries made from nuclear waste

Sustainable energy sources are an immediate need to cope with the imminent issue of climate change the world is facing today.In particular,the long-lasting miniatured power sources that can supply energy continually to power handheld gadgets,sensors,electronic devices,unmanned airborne vehicles in space and extreme mining are some of the examples where this is an acute need.It is known from basic physics that radioactive materials decay over few years and some nuclear materials have their half-l...     

Trial Manufacture of Core Subassemblies of CEFR

Engineering department of CEFR selected factories to research manufacturing process of subassemblies in March 2001. By November 2001, the trial productions of several materials have been completed. Meanwhile two B4C shielding subassemblies and two support legs of steel reflecting subassembly, which are used in hydrodynamic and structural stability out-of-pile tests, and three B4C rods which are irradiated in-pile have been assembled.     

Proton induced gamma ray emission analysis of nitrogen

The proton-capture reactions 14N(p,γ)15O and 15N(p,αγ)^12C have been studied to determine their applicabilities to the analysis of materials for 15N enrichment,It is true that precision of the measurement concerned in these techniques cannot compete with mass spectrometry,but their ease of application is of great advantage to the fast handling of very large batches of samples from stable nuclide tracer experiments.     

Main Directions and Recent Test Modeling Results of Lithium Capillary-Pore Systems as Plasma Facing Components

At present the most promising principal solution of the divertor problem appears to be the use of liquid metals and primarily of lithium Capillary-Pore Systems (CPS) as of plasma facing materials. A solid CPS filled with liquid lithium will have a high resistance to surface and volume damage because of neutron radiation effects, melting, splashing and thermal stressinduced cracking in steady state and during plasma transitions to provide the normal operation of divertor target plates and first-wall protecting elements. These materials will not be the sources of impurities inducing an increase of Zeef and they will not be collected as dust in the divertor area and in ducts. Experiments with lithium CPS under simulating conditions of plasma disruption on a hydrogen plasma accelerator MK-200 [-(10 - 15) MJ/m^2, - 50 μs] have been performed. The formation of a shielding layer of lithium plasma and the high stability of these systems have been shown. The new lithium limiter tests on an up-graded T-11M tokamak (plasma current up to 100 kA, pulse length -0.3 s) have been performed. Sorption and desorption of plasma-forming gas, lithium emission into discharge, lithium erosion, deposited power of the limiter are investigated in these experiments. The first results of experiments are presented.     

利用同步辐射进行氟塑料的表面改性与微器件制造研究

It is well-known that fluorinated polymers are very unique polymer materials because of their distinguished properties, such as high electrical resistivities, chemical and thermal stabilities, bio-compatibilities, etc. However,polytetrafluoroethylene (PTFE) is degraded by ionizing radiation with a low dose through main chain scission, and the mechanical properties are seriously deteriorated. In early 1990's, it was found that irradiation for PTFE at elevating temperature enhances recombination of radicals induced by ionizing radiation. Thus, crosslinked PTFE had been obtained[1,2]. The crosslinked PTFE shows remarkable improvements for the radiation durability and mechanical properties, etc.We have performed micro-fabrication by means of synchrotron radiation (SR) for various kinds of PTFEs including crosslinked PTFEs. The direct photo--etching technique using SR is known as TIEGA() technology,which has been developed by Sumitomo Heavy Industries, Ltd. The technology was applied for the micro-fabrication of fluorinated polymers. It has been found that etching rates obtained for crosslinked PTFEs were much larger than those of the non-crosslinked. The fact is strange from the viewpoint of radiation durability of crosslinked PTFEs. Hence, the results are not described by simple consideration such as the G-values of main chain scission. We have proposed that the etching rates should be controlled by the complex mechanism through at least two different steps as polymer decomposition and fragment desorption mechanisms.On the other hand, we have found that abnormal reactions were induced at the surface region under the SR etching for the various kinds of fluorinated polymers. Through the measurements using differential scanning calorimetory (DSC) and solid state 19F-NMR, we have confirmed crosslinking reactions for the polymers even in solid states. This reaction should be induced by the very high density radicals formation and their recombination in very localized area of the polymers under the SR etching processes.     

High-energy radiation and polymers: A review of commercial processes and emerging applications

Ionizing radiation has been found to be widely applicable in modifying the structure and properties of polymers, and can be used to tailor the performance of either bulk materials or surfaces. Fifty years of research in polymer radiation chemistry has led to numerous applications of commercial and economic importance, and work remains active in the application of radiation to practical uses involving polymeric materials. This paper provides a survey of radiation-processing methods of industrial interest, ranging from technologies already commercially well established, through innovations in the active R&D stage which show exceptional promise for future commercial use. Radiation-processing technologies are discussed under the following categories: cross-linking of plastics and rubbers, curing of coatings and inks, heat-shrink products, fiber–matrix composites, chain-scission for processing control, surface modification, grafting, hydrogels, sterilization, natural product enhancement, plastics recycling, ceramic precursors, electronic property materials, ion-track membranes and lithography for microdevice production. In addition to new technological innovations utilizing conventional gamma and e-beam sources, a number of promising new applications make use of novel radiation types which include ion beams (heavy ions, light ions, highly focused microscopic beams and high-intensity pulses), soft X-rays which are focused, coherent X-rays (from a synchrotron) and e-beams which undergo scattering to generate patterns.     

Photoradiation processes in combined polymeric materials

The methods of ESR, optical and mass-spectroscopy have been used to study the formation and decay of active intermediates, radiation and photoradiation gas evolution in a series of combined polymeric materials. The investigated samples were films of polyimide (PI), one- or two-side coated PI–fluoroplast, poly(ethylene terephthalate) (PET), PET coated with polyacryl on both sides, etc.Different coatings and polymeric substrates have been established to produce a mutual effect on the radiation- and photo-induced transformations of the combined polymers at the stage of radical formation and gas evolution. Thus, γ-irradiation of PI–fluoroplast films at 300 K intensifies the radiation-chemical processes in the fluorinated coatings, namely, the radiation-chemical yield of macroradicals in the coatings is several times higher than that in fluoro-containing polymers. In the PET film coated with polyacryl the yield of macroradicals related to polyacrylic acid is significantly lower than the value generally cited in the publications. A mutual effect of the coatings and substrates on the radiation and photoradiation-induced gas evolution is even more noticeable. Thus, a gas mixture of the PI–fluoroplast film contains lower amounts of carbon oxide and fluorinated products and no hydrogen at all. The interphase processes, distortion of the boundary layer structure, electronic equilibrium, mutual effect of the evolved gases, etc. can account for the reasons of such non-additivity.     

同步辐射X射线光刻应用新领域—LIGA技术

介绍了一种超微细加工新方法－ＬＩＧＡ技术对掩模材料、光刻胶和光源的要求予以讨论，同时还介绍了国外在这方面的最新研究成果，ＬＩＧＡ技术是深度Ｘ射线刻蚀，电铸成型和塑料铸模等技术相结合的综合技术，是制造微型机械最有前途的方法，与传统半导体超微细加工方法相比，ＬＩＧＡ技术有以下优点：（１）用材广泛，可以是金属、陶瓷、聚合物及玻璃；（２）可加工任意复杂的图形结构；（３）可制造有较大高宽比的超微细元件；（４     

Radiation stability of vitrified radioactive preparations

Data are cited on the effect of ionizing radiations on the chemical stability of vitreous materials intended for radioactive waste disposal. It is shown that exposure in air leads to a change in the chemical composition of the surface of specimens as a result of heterogeneous radiation-chemical reactions involving the solid preparations and components of the air. Suggested reaction products are carbonates, hydroxides, and nitrates.Translated from Atomnaya Énergiya, Vol. 18, No. 4, pp. 361–367, April, 1965     

Monte Carlo study of molecular weight distribution changes induced by degradation of ion beam irradiated polymers

In this work we study a polymeric material that degrades upon irradiation due to the energy inhomogeneously deposited by heavy ion beams. Ion beam irradiation of polymers generates rather different effects than those induced by “classical” low ionizing particles such as electrons or gamma rays. This is due to the high electronic stopping power and the inhomogeneous distribution of deposited energy. This energy is transferred to the material within a small volume along the ion path forming the so called “nuclear track” or “latent track”. The track size primarily depends on the ion velocity, and it is determined by the secondary electrons (delta rays) generated along the ion trajectory. By means of Monte Carlo simulations we first obtained equilibrated polymer configurations using a coarse-grained model, and then investigated the spatially inhomogeneous chain scission process due to the passage of the ions. The number average molecular weight, weight average molecular weight and the polydispersity were calculated as a function of track radius, scission probability within the ion track and irradiation fluence. Finally we compared our results with a numerical implementation of a model for random homogeneous degradation.     

辐射交联聚合物的结晶动力学(英文)

电离辐射在工业上应用的基础是聚合物的辐射交联,它们是绝缘电线和电缆的交联,热收缩性材料的生产,泡沫塑料等等。辐射引发交联已经被广泛地研究,特别是凝胶的形成和聚合物结构、辐照条件对交联度的影响。对于一般法和辐射法交联的聚合物却很少有人研究它的结晶过程。例如,已经证明除了在非常高的吸收剂量外,辐照的聚乙烯中总的结晶度不受影响,但对于聚丙烯和聚丁烯在凝胶点剂量时,它们的结晶度大大减少。辐照聚合物的重新熔融,进一步减少了总结晶度。 本工作表明不仅总的结晶度而且结晶动力学也受辐射引发交联的影响。结晶速率指出结晶划分成二种不同增长机理的过程。冷却速率是一个重要的因素,它决定结晶过程并影响与交联的半晶聚合物的结晶度和形态有关的其它性质。     

高能重离子在聚合物中的辐照效应研究

Ion irradiation of polymers can induce irreversible changes in their macroscopic properties such as electrical and optical properties and the surface-related mechanical properties. Electronic excitation, ionization, chains scission, cross-links and mass losses are accepted as the fundamental events that give rise to the observed macroscopic changes. Detailed and systematic study of radiation induced effects in polymers enriches not only the knowledge of ion-material interactions but also supplies new bases for polymeric materials synthesis through ion-beam technologies. Previous work has concentrated mainly on effects induced by low-ionization particles such as γ-rays and electrons. Since 1980,s the application of high energy heavy ion accelerators enables the use of high energy heavy ion as an irradiation source, and many new and exciting effects and phenomena have been revealed.Energetic heavy ions in matter lose energy mainly through electronic excitation and ionization. Compared to low-ionization particles, high energy heavy ion possesses higher LET(linear energy transfer) values which can reach several to several tens keV/nm. As most of the primary ionizations and excitations occur close to the ion trajectory in a core of a few nanometers in diameter, a continuous damaged zone along the ion path can be induced,in which all bonds inside the zone can be destroyed due to the high rate energy deposition. Studies on this particularity of high energy heavy ion irradiation and its effects in materials will cause great influence on industry as well as on our daily life.The previous work has revealed the great difference in the effects induced by high energy heavy ions compared to the other particles. It has been shown that under irradiation with lower LET particles gas release depends on molecular structure and material composition, whereas under irradiation with high LET particles, such as high energy heavy ions, it is not the case. Some materials that undergo degradation under γ-irradiation can be cross-linked by irradiation with high energy heavy ions. In some cases new molecular structures were induced by high energy heavy ions with sufficiently high LET values. In recent years we have irradiated polyethylterephthalate (PET), polystyrene (PS), polycarbonate (PC) and polyimide (PI) with high energy Ar, Kr, Xe and U ion beams.Chemical and physical changes of the materials induced by the high energy heavy ion beams were investigated by Fourier-transform infrared ray spectroscopy, ultraviolet and visible transmission spectroscopy and X-ray diffraction measurements, from which damage cross-sections of various functional groups were determined[1]. An energy loss threshold for damage of phenyl ring in PET has been derived and difference in amorphization of PET under high and low LET irradiations was observed. It is found that alkyne end groups can be induced in all the materials above a certain electronic energy loss threshold, which is found to be about 0.8 keV/nm for PS and 0.4 keV/nm for PC. The production cross-section of alkyne end group increases with increasing electronic energy loss and shows saturation at high electronic energy loss values.     

PTFE的辐射裂解、交联及其应用

聚四氟乙烯（PTFE）是一种性能优异的工程塑料,通常被认为是典型的辐射裂解材料。PTFE可以在不同条件下实现裂解并生成PTFE微粉。在高于PTFE的熔点即温度为330～340℃,真空或惰性气氛下进行辐照,可实现PTFE的交联。本工作综述了PTFE辐射裂解和交联研究的历史和最新进展,并对交联PTFE在润滑材料、燃料电池、光刻等领域的应用进行了介绍。     

Effects of ion beam treatment on atomic and macroscopic adhesion of copper to different polymer materials

Low-energy ion irradiation of polymer induces different phenomena in the near surface layer, which effect strongly the metal-polymer interface formation and promotes adhesion of polymers to metals. Low-energy argon and oxygen ion beams were used to alter the chemical and physical properties of different polymers (PS (polystyrene), PαMS (poly(α-methylstyrene), BPA-PC (bisphenol-A-polycarbonate) and PMMA (poly(methyl methacrylate)), in order to understand the adhesion phenomena between a deposited Cu layer and the polymers. The resulting changes were investigated by various techniques including X-ray photoelectron spectroscopy, measurements of the metal condensation coefficient and a new technique to measure cross-linking at the polymer surface. Two types of practical adhesion strengths of Cu-polymer systems, measured using 90° peel tests, were observed: (i) peel strength increased at low ion fluences, reached a maximum and then decreased after prolonged treatment and (ii) no improvement in the peel strength on treated polymer surfaces was recorded. The improvement in the metal-polymer adhesion in the ion fluence range of 10¹³-10¹⁵ cm⁻² is attributed to the creation of a large density of new adsorption sites resulting in a larger contact area and incorporation of chemically active groups that lead to increased interaction between metal and polymer by metal-oxygen-polymer species formation. XPS analysis of peeled-off surfaces showed that in most cases the failure location changed from interfacial for untreated polymers to cohesive failure in the polymer for treated surfaces. These observations and measurements of the metal condensation coefficients suggest that bonding is improved at the metal-polymer interface for all metal-polymer systems. However, the decrease in the peel strength at high ion fluences is attributed to the formation of a weak boundary layer in polymers. The correlation between sputter rate of polymers and altering in the peel strength for moderate ion fluences was determined. It was observed that the metal-polymer adhesion could be improved for PS and BPA-PC, which have a low sputter rate and preferentially formed cross-links in the treated surface. For degrading polymers, like PαMS and PMMA, chain scission rather than cross-linking dominates, low molecular weight species are formed and no adhesion enhancement is observed.