预辐射接枝法制备FEP-g-PSSA/AA膜

采用γ射线预辐射接枝方法制备了FEP—g—PSSA／AA膜，反应制得的接枝膜是一种含氟磺酸型质子交换膜。系统研究了影响接枝反应的阻聚剂用量、膜的厚度、单体摩尔比及总摩尔浓度变化等因素。结果表明，丙烯酸（Acrylic acid，AA）与苯乙烯磺酸钠（Sodium styrene sulfonate，SSS）对全氟乙丙烯（Polytetranuoroethyleneco-hexanuoropropylene，FEP）的接枝率几乎不受膜厚度变化的影响，而且全氟乙丙烯（FEP）辐照后放置三个月再进行接枝反应，接枝率也几乎没有变化。     

电子束引发双功能基阳离子交换膜的制备研究

在所有的离子交换膜中,最引人注目的当数20世纪70年代已商品化的Nation系列膜。具有磺酸功能基的Nation膜电阻低,但用在氯碱工业时电流效率低。1974年Seko发明了全氟羧酸阳离子交换膜,使电流效率有实质性提高,并推动了复合膜的发展。复合膜具有磺酸膜的低电阻性能和羧酸膜的高电流效率。本工作采用辐射接枝法制备含羧酸基团和磺酸基团的双功能基阳离子交换膜,目的主要是以低成本且简单可行的辐射接枝法代替共聚法,制备稳定性好、低电阻、高电流效率的阳离子交换膜。     

质子交换膜燃料电池动态加载过程的模拟研究

动态特性是影响质子交换膜燃料电池性能的关键问题之一。通过对直通道质子交换膜燃料电池进行简化建模,选取合适的参数进行数值计算,比较不同电流密度加载时间以及加载幅度的情况下,燃料电池的电压和正负极气体浓度响应情况,进而研究燃料电池动态加载特性。结果表明:增加电流密度加载过程时间同时减小加载幅度,有利于提高电池的稳定性,延长电池寿命。变载时,阴极达到稳定所需的时间更短。     

磺酸型阳离子交换膜的性能研究

通过辐照接枝法在高密度聚乙烯(HDPE)上引入磺酸基团,从而制备了一种强酸性阳离子交换膜。就所制备离子交换膜的热稳定及化学稳定性能进行了详细考察。结果表明,接枝膜上引入磺酸基团后抗氧化性能较仅含羧酸基团的离子交换膜有所提高,接枝膜的热稳定性较之接枝前稍差,热重分析表明,接枝后样品的成碳量较接枝前有相当大的提高,原因归结于表面接枝层对成碳过程有促进作用。由于接枝膜中HDPE组份的“结晶破坏”及接枝链对晶区的“稀释作用”综合影响,结晶度随着接枝率的升高而降低。     

GMR薄膜抗辐照性能研究

研究了两种不同材料构成自旋阀结构的巨磁电阻(Giant magneto resistance,GMR)多层膜受质子辐照、电子辐照和γ射线辐照的影响。实验结果表明,辐照会引起磁电阻率的略微下降,但降幅均低于10%,并且GMR薄膜的矫顽力和交换场并不受辐照的影响。对比发现,GMR元件受太空环境中以质子辐射为主的影响非常小,这表明GMR元件在空间应用中具有广阔的前景。     

辐射接枝高分子电解膜的制备、表征及其在燃料电池中的应用

高分子电解膜是高分子燃料电池的关键材料之一。担当着阴阳极反应原料的隔离及离子电导的功能,其性能决定着燃料电池的性能、成本及应用前景。辐射接枝电解膜由氟化的高分子骨架及磺化的接枝高分子链构成。前者赋予电解膜必要的强度、尺寸稳定性及低气体透过性,后者赋予其质子电导功能。综述了基材、单体及交联剂的筛选、合成工艺的调整等与辐射接枝电解膜的性能关系。     

铜镍矿样中铂和钯的离子交换预富集中子活化分析研究

在铂族元素中子活化分析中，应用溶剂萃取和磺酸型阳离子交换树脂相结合的方法，分离富集铜镍矿样中铂、钯的化学前处理流程，并对与该流程结合的中子活化方法进行了概述。各项相关参数均表明该方法可用于铜镍矿样中的铂钯分析。     

HDPE预辐照接枝SSS与AA体系的反应动力学研究

采用电子束引发预辐照接枝方法在高密度聚乙烯(HDPE)上接枝丙烯酸(AA)与对苯乙烯磺酸钠(SSS)两种单体,以制备含磺酸和羧酸基团的双功能基阳离子交换膜。研究发现,接枝速率与辐照剂量、单体总浓度及反应温度密切相关。接枝反应的活化能为22．2kJ／mol。傅立叶变换红外光谱(FTIR)测试表明,接枝膜上引入了磺酸基团和羧酸基团。     

薄窗型多阳极气体探测器研究进展

薄窗型气体探测器是最近发展并用于低能量加速器质谱探测技术。该探测器的入射窗采用氮化硅膜,薄而均匀,分辨率高,目前已在低能量粒子探测技术中得到初步应用,显示出广泛的应用前景。本文主要从薄窗型气体探测器基本原理、薄氮化硅膜与Mylar膜的对比、不同质子数Z的低能量粒子脉冲高度对比、薄窗型气体探测器与硅探测器的对比,以及应用等方面进行阐述。     

薄窗型多阳极气体探测器研究进展

薄窗型气体探测器是最近发展并用于低能量加速器质谱探测技术。该探测器的入射窗采用氮化硅膜,薄而均匀,分辨率高,目前已在低能量粒子探测技术中得到初步应用,显示出广泛的应用前景。本文主要从薄窗型气体探测器基本原理、薄氮化硅膜与Mylar膜的对比、不同质子数Z的低能量粒子脉冲高度对比、薄窗型气体探测器与硅探测器的对比,以及应用等方面进行阐述。     

Radiolytic preparation of poly(styrene sulfonic acid) - grafted poly(tetrafluoroethylene-co-perfluorovinyl vinyl ether) membranes with highly cross-linked networks

In this study, various amounts of a divinylbenzene (DVB) cross-linking agent (5∼30%) were introduced during a simultaneous irradiation grafting of styrene onto a PFA film of a 25 μm thickness in order to prepare a series of poly(styrene sulfonic acid)-grafted poly(tetrafluoroethylene-co-perfluorovinyl vinyl ether) (PFA) membranes with various degrees of cross-linking and grafting (29∼74%). The effects of the DVB cross-linking agent on the properties of the prepared membranes, such as water uptake, proton conductivity, methanol permeability, and chemical stability, were also investigated in this study. The results indicated that the ion exchange capacity (IEC) slightly decreased with increasing DVB content, whereas the water uptake, proton conductivity, and methanol permeability of the membrane greatly decreased. The chemical stability of the prepared membranes was found to be significantly improved with increasing DVB content. The results indicated that the cross-linked network membranes are promising for application in a direct methanol fuel cell.     

Development of function-graded proton exchange membrane for PEFC using heavy ion beam irradiation

The graded energy deposition of heavy ion beam irradiation to polymeric materials was utilized to synthesize a novel proton exchange membrane (PEM) with the graded density of sulfonic acid groups toward the thickness direction. Stacked Poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) films were irradiated by Xe⁵⁴⁺ ion beam with the energy of 6 MeV/u under a vacuum condition. The induced trapped radicals by the irradiation were measured by electron spin resonance (ESR) spectroscopy. Irradiated films were grafted with styrene monomer and then sulfonated. X-ray photo-electron spectroscopy (XPS) spectra showed that the densities of sulfonic acid groups were controlled for injection “Surface” and transmit “Back” sides of the fabricated PEM. The membrane electrode assembly (MEA) fabricated by the function-graded PEM showed improved fuel cell performance in terms of voltage stability. It was expected that the function-graded PEM could control the graded concentration of sulfonic acid groups in PEM.     

Preparation and characterization of proton exchange membranes from polystyrene grafted poly（vinylidene fluoride） powder

Proton exchange membranes(PEMs) were prepared in three steps:graRing of polystyrene onto PVDF powder using pre-irradiation graft polymerization technique, processing the grafted PVDF powder into membranes of around 50-μm thickness, and sulfonating them with cholorosulfonic acid to form poly(vinylidene fluoride)-g-poly(styrene sulfonic acid) membranes. Kinetics of the graft polymerization was studied. The existing of polystyrene side-chains in the grafted PVDF powders, and PSSA groups in PEMs, were proved by FT-IR. Properties of the PEMs, i.e. the ion exchange capacity, water uptake, proton conductivity, thermal property and oxidative stability,were characterized. Dependence of properties on the degree of grafting was investigated, too.     

Development of sulfonated FEP-Nafion hybrid proton exchange membranes for PEFC

The performance of polymer electrolyte fuel cell (PEFC) is affected by an interfacial property between a proton exchange membrane (PEM) and electrodes. Thus, to develop a well-laminated membrane electrode assembly (MEA), a hybrid PEM (FN) was fabricated by mixing a radiation grafted membrane (sulfonated FEP) with ionomer (Nafion^® dispersion) which is applied to coat the interface of the PEM and electrodes.The obtained FN, sulfonated FEP and Nafion^®112 were characterized in terms of water uptake, ion exchange capacity (IEC), polarization performance and electrochemical impedance. FN showed high IEC and water uptake, which would induce the highest ionic conductivity (IC) among tested PEMs. In terms of FN, the interface between the PEM and electrodes should have been improved because FN showed the lowest charge transfer resistance than other tested PEMs. The high IC and improved interface between the PEM and electrodes resulted in the best cell performance of FN in tested PEMs.     

An Approximate Solution to Space Dependent Kinetics Problems

The degree of dissociation of hydrated polystyrene divinylbenzene sulfonic acid ion exchange resin was measured by nuclear magnetic resonance technique. The acid dissociation constant of ion exchange resin calculated from the chemical shifts was 0.7. The degree of dissociation of the hydrogen ions was found to be affected by the coexisting metal ions.     

纳米二氧化铈杂化改性SDB载体的合成及模拟吸附

氢-水液相催化交换(LPCE)是处理核电含氚废水的有效途径,其中疏水载体苯乙烯-二乙烯基苯共聚物(SDB)是LPCE的关键材料,影响活性组分Pt的分散与稳定。通过纳米CeO₂表面改性,原位聚合制备了超疏水(静态水接触角152.96°)、高强度(113.54 N)的纳米CeO₂杂化改性苯乙烯-二乙烯基苯共聚物(Y-CeO₂/SDB),且具有较好的热稳定性。模拟研究了SDB、Y-CeO₂/SDB载体对Ni²⁺的吸附特征,结果表明:SDB对Ni²⁺的吸附主要为物理吸附,Y-CeO₂/SDB则以化学吸附为主。     

A New Model for Exchange of Deuterium in Oxide Ceramics for Protium in Light Water Molecule at Room Temperature

For exchange of deuterium (D) in oxide ceramics for protium (H) in light water molecule at room temperature is proposed the one way diffusion model: absorption of proton and adsorption of OH^- due to dissociation of H₂O at the surface, diffusion of proton, release of deuteron in trapping site due to local molecular recombination with proton and the subsequent trapping of another proton into the vacant trapping site. The one way diffusion model has been formulated in form of the mass balance equations for free proton and both proton and deuteron trapped in trapping sites which include the rate constants of chemical reactions for proton described above. The solutions of the concentrations of deuterons retained and protons uptaken in the specimen have been fitted to the experimental data and the rate constants of the chemical reactions relevant to the D-H exchange have been determined. The rate constants of the chemical reactions are discussed. Moreover, potential applications of the one way diffusion model are discussed.     

新型多条多气隙阻性板探测器的性能测试

为提高德国FOPI系统飞行时间的探测本领,运用新型多条多气隙阻性板探测器对FOPI系统进行升级改造。探测器的制作已完成,为保证探测器的质量,对它们进行了一系列的测量和质量确认。测试结果证明,系统的本底计数率分布在0.2Hz/cm²附近,工作高压9.6kV;利用γ射线放射源测试,时间分辨（包括闪烁体的时间分辨）分布在220～280ps之间;采用质子束流测量,其探测效率可达98%以上,时间分辨可达75ps     

Durability of Irradiated Polymers in Solid-Polymer-Electrolyte Water Electrolyzer

The durability of irradiated organic polymers in solid-polymer-electrolyte water electrolyzer was investigated by gamma-ray irradiation tests around 500 kGy. Serious deteriorations for the tensile strength and ion exchange capacity of the ion exchange membrane (Nafion®) were not observed up to 850 kGy. No serious damage was also observed for tensile strength of the gasket materials (Aflas®) up to 500 kGy. The insulator materials (PFA and FEP) lost their tensile strength at 200 kGy and 300 kGy, respectively. From the above results, we can safely say that the electrolysis cell could be used up to around 500 kGy of irradiation conditions in the case where PFA and FEP are replaced by the polyimide resin which durability against the irradiation is well demonstrated. Two degrading mechanisms were supposed as the effect of irradiation. One is the direct degradation of the chain and branch by gamma-ray. The other is degradation by the attack of radicals. It was demonstrated that the effect of radicals on degradation of the membrane was not dominant. In addition, oxygen was observed to have a large influence on degradation. The quantity of dissolved fluorine in water that could be measured easily was found to correlate closely with tensile strength and ion exchange capacity. Hence, it is possible to evaluate the degradation of ion exchange membrane by monitoring the quantity of dissolved fluorine in water. Concerning the difference of degrading mechanism of the ion exchange membrane due to irradiation source, the combinations of tensile strength, ion exchange capacity and quantity of dissolved fluorine are proposed as deterioration indexes.