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(Polytetrafluoroethylene- co-hexafluoropropylene, 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。     

HDPE膜预辐照接枝VBTAC制备阴离子交换膜

在氮气保护下,利用预辐照接枝技术在高密度聚乙烯（HDPE）膜上接枝苯乙烯三甲基氯化铵（VBTAC）单体,以甲基丙烯酸二甲氨基乙酯（DMAEMA）单体作为接枝辅助单体来提高VBTAC的接枝率,制备出阴离子交换膜,解决了在HDPE上难以直接接枝聚合VBTAC的问题。本文研究了接枝条件及接枝液的组分对接枝的影响,并用X射线显微分析方法研究了VBTAC的接枝进程和接枝分布。     

用辐射接枝法对HDPE膜进行功能化改性

利用预辐射接枝技术,在聚乙烯膜上接枝苯乙烯磺酸钠（ＳＳＳ）、苯乙烯三甲基氯化铵（ＶＢＴＡＣ）等具有离子交换性能的单体,研制出具有抗菌性能的离子交换膜,并且使得原先增水性的基膜转变为亲水性较好的膜。通过实验,掌握了膜的接枝工艺,并对膜接枝过程、结构特征、经性能有较多的了解。从各个角度对膜的亲水性能作了定量研究,提出了水合数与表面自由能的计算方法。对几种膜的抗菌性能进行了评价。确定了ＶＢＴＡＣ膜作为抗     

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。     

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。     

聚四氟乙烯膜辐射接枝反应条件的研究

采用了共辐射接枝技术,在室温下将苯乙烯接枝到聚四氟乙烯薄膜上,合成了辐射接枝膜。研究了溶剂种类、单体浓度、辐射剂量以及剂量率等因素对接枝反应的影响。结果表明,单体浓度和辐射剂量率是反应的主要影响因素,两者对接枝反应速率的影响指数分别为1．2和0．4。     

辐射接枝制备电池隔膜研究现状

电池隔膜的制备方法有许多种,其中聚合物膜辐射引发接枝功能型单体是电池隔膜制备的重要手段之一。通过辐射接枝不同的单体,可以赋予聚合物薄膜特定的电化学和物理化学等性能,使其符合不同种类电池对隔膜的技术要求。本工作详细介绍了辐射接枝法制备电池隔膜的研究和应用状况。     

预辐射引发气相接枝法制备PE-g-PAN材料

氰基是一类化学活性较高的基团,可以制备各种配位基团。接枝聚丙烯腈是引入氰基的主要方法之一。本文利用γ射线预辐射气相接枝的方法将丙烯腈接枝聚合到聚乙烯（PE）无纺布上,系统地研究了接枝率在不同温度、时间和吸收剂量时的变化规律。通过傅里叶变换红外光谱仪（Fourier transform infrared spectroscopy,FTIR）、拉力、扫描电子显微镜（Scanning electron microscope,SEM）、接触角等表征了样品的理化性能。结果证明,通过预辐射气相接枝方法可以成功的将丙烯腈接枝聚合到聚乙烯无纺布上;接枝聚丙烯腈后,无纺布的接触角会略有提高;无纺布受辐照后,机械性能下降,而接枝聚丙烯腈对无纺布的机械性能影响较小。     

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.     

过氟化聚合物的苯乙烯接枝研究--辐照条件与反应条件的影响

Fuel cell is in focus as a very low exhaust new dynamo system. Especially polymer electrolyte fuel cells (PEFC) using proton exchange membranes (PEM) have attracted much attention for the electrical vehicle and other mobile applications such as cellar phone and personal computer. Conventional perfluoro-sulfonic acid membranes such as Nation() (DuPont de Nemours LTD.) have been the popular PEM used in PFEC. However, there are still several problems such as insufficient gas barrier properties, low thermal resistance, and their high costs.In this study, hawse have studied the partially fluorinated PEM for PEFC by radiation grafting onto per-fluorinated polymers such as PFA, FEP and ETFE with reactive styrene monomers using pre-irradiation grafting method in gas and in liquid phase, respectively, and successive sulfonation. Characteristic properties of the grafted and sulfonated materials have been discussed and optimized fabricating conditions were determined.Characteristic properties of the obtained materials have been measured by differential scanning calorimetry,thermogravimetric analysis and FT-IR spectroscopy, etc.In the case of irradiation in air, glass transition temperatures (Tg) of the grafted materials depend on the yields of styrene grafting onto the materials. That is higher yields of grafting give lower thermal stability. On the other hand, when the peroxy radicals were converted trapped radicals by exposure in air after irradiation under oxygen-free atmosphere, Tg of the grafted materials hardly depends on the grafting yields.Moreover, the yields of grafting in gas phase were higher than that of liquid phase. However, the sample form of grafting in gas phase has been greatly changed, whereas the sample form of grafting in liquid phase has kept its original feature.Therefore, it is suggested that the fabricating conditions for PEFC membranes were preferred to irradiation under oxygen-free atmosphere and grafting in liquid phase.Ion exchange capacities of the sulfonated-materials could be 3.0meq/g. Other properties of the obtained membranes such as chemical structure were also discussed.     

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.     

Radiation synthesis and characteristics of PTFE-g-PSSA ion exchange membrane applied in vanadium redox battery

Radiation-induced grafting of styrene onto polytetrafluoroethylene （PTFE） membranes was studied by a simultaneous irradiation technique. Grafting was carded out using γ-radiation from a ^60Co source at room temperature. Effects of absorbed dose, atmosphere, dose rate, and the concentration of initial monomer on the degree of grafting （DOG） were investigated and the most appropriate grafting condition was obtained. Subsequently, sulphonation of the grafted PTFE membrane （PTFE-g-PS） was carded out and a series of ion exchange membranes （PTFE-g-PSSA） was prepared. Further characterizations of FTIR, TGA, and SEM testified that grafting and sulphonation of the membranes were successfully processed; moreover, grafting of styrene not only occurred in the surface of PTFE membrane, but also in the micropores of the membrane. Ion exchange capacity （IEC） and conductivity were found increase with the grafting yield. The results suggest that at a low dose, such as 17 kGy, the ion exchange membrane （IEM） which will be suitable for vanadium redox battery （VRB） use can be obtained.     

Proton exchange membranes prepared by radiation-induced graft copolymerization from binary monomer mixtures onto poly(tetrafluoroethylene-co-hexafluoropropylene) film

Sulfonic acid proton exchange membranes based on a poly(tetrafluoroethylene-co-hexafluoropropylene) film were synthesized through the single-step graft copolymerization of sodium styrenesulfonate and acrylic acid monomers from binary monomer aqueous solutions using the electron beam pre-irradiation method in air. The effects of the various polymerization parameters (absorbed dose, reaction time, and monomer ratio) on the degree of grafting were studied.A correlation between the degree of grafting and some of the physical-chemical properties (water uptake and ion-exchange capacity) of the synthesized copolymers was established. The distribution of the sulfonic acid groups was investigated across the thickness of several membranes in order to gain a better understanding of the graft copolymerization process from binary monomer aqueous solutions onto the fluorinated film and to synthesize membranes with optimal physical-chemical properties.     

Surface molecular degradation of high performance carbon/bismaleimide composites induced by proton irradiation

This work aims to identify and describe the effects of proton irradiation in ultra high vacuum environment on the surface degradation of high performance carbon/bismaleimide composites used in aerospace. The changes in surface molecular structure and surface chemical composition with increasing irradiation fluence were studied by Attenuated total reflection Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, respectively. The evolution of surface morphology and surface roughness were characterized by atomic force microscopy. The results indicated that the proton irradiation caused surface degradation of the carbon/bismaleimide composites by altering their surface chemical structure and surface morphology. The surface chemical bonds were broken largely and the extent of carbonification at the surface layer of the composites was enhanced with increasing irradiation fluence. The increment in the carbon concentration and the sharp reduction in the oxygen and nitrogen concentration with increasing irradiation fluence were caused by the emission of some oxygen-containing and nitrogen-containing small molecules from the material surface under high vacuum environment. The surface roughness firstly increased under the fluence lower than 5 × 10¹⁵ cm⁻², and then decreased after the irradiation fluence increased to some extent.     

电子束刻蚀聚碳酸酯制备微孔分离膜

以电子束刻蚀技术和聚碳酸酯(Polycarbonate,PC)材料本身的辐照裂解特性,结合微孔掩膜和溶液氧化腐蚀的方法,成功制备了具有规则垂直孔道的PC微孔分离膜。用乌氏粘度计、凝胶渗透色谱仪、仪和傅里叶红外光谱分析仪表征辐照PC的结构和性能变化。结果表明,PC材料的黏均相对分子量、数均分子质量、玻璃化温度、黏均聚合度均随吸收剂量的增加而下降;红外分析表明PC在电子束照射下发生主链断裂;动力学分析表明其辐照降解属于无规降解类型,为电子束刻蚀制备PC微孔分离膜技术提供了理论依据。     

Magnetic force microscopy studies on the magnetic ordering in organic materials induced by high-energy proton irradiation

In this study, ferromagnetic microstructures in highly oriented pyrolytic graphite and superparamagnetic spots in polyimide foils were created by 2.25 MeV proton microbeam irradiation and characterized using atomic and magnetic force microscopy. For this purpose, graphite samples were irradiated with cross-like patterns of 15 μm × 15 μm size using ion fluences in the range of (0.003–2.5) × 10¹⁸ cm⁻². The irradiated crosses showed strong magnetic signals and a complex domain structure in the magnetic images depending on the geometrical dimensions of the crosses. Furthermore, polyimide foils were irradiated with microspots and fluences in the range of (0.016–3.1) × 10¹⁹ cm⁻². Magnetic force microscopy shows very strong phase shifts in these irradiated areas.     

Preparation of cobalt nanoparticles by electron beam irradiation

and laser mattering particle size distribution analysis. Average size of the nanoparticles was about 32 nm with a narrow size distribution. Melting point of the nanoparticles was about 451.3 ℃.     

Creation of 3D microsculptures in PMMA by multiple angle proton irradiation

In recent years the technique of proton beam writing has established itself as a versatile method for the creation of microstructures in resist materials. While these structures can be almost arbitrary in two dimensions, the creation of genuine 3D structures remains a challenge.At the LIPSION accelerator facility a new approach has been developed which combines aspects of ion beam tomography, so far solely an analysis method, with proton beam writing. Key element is the targeted irradiation from multiple angles in order to obtain a much broader range of 3D microstructures than has hitherto been possible.PMMA columns with a diameter of ∼90 μm were used as raw material and placed in an upright position on top of a rotational axis. Using 2.25 MeV protons patterns corresponding to the silhouettes of the desired structures were written from two or more directions. In a subsequent step of chemical etching irradiated portions were dissolved, leaving behind the finished 3D sculpture.Various objects have been created. For the demonstration of the method a 70 μm high model of the Eiffel tower has been sculpted by irradiation from two angles. Using irradiation from three angles a 40 μm wide screw with right-handed thread could be crafted which might find applications in micromachining. Also, a cage structure with a pore size of ca. 20 μm was written with the intention to use it as a scaffold for the growth of biological cells.