The influence of radiation-induced vacancy on the formation of thin-film of compound layer during a reactive diffusion process

A theoretical approach is developed that describes the formation of a thin-film of AB-compound layer under the influence of radiation-induced vacancy. The AB-compound layer is formed as a result of a chemical reaction between the atomic species of A and B immiscible layers. The two layers are irradiated with a beam of energetic particles and this process leads to several vacant lattice sites creation in both layers due to the displacement of lattice atoms by irradiating particles. A- and B-atoms diffuse via these lattice sites by means of a vacancy mechanism in considerable amount to reaction interfaces A/AB and AB/B. The reaction interfaces increase in thickness as a result of chemical transformation between the diffusing species and surface atoms (near both layers). The compound layer formation occurs in two stages. The first stage begins as an interfacial reaction controlled process, and the second as a diffusion controlled process. The critical thickness and time are determined at a transition point between the two stages. The influence of radiation-induced vacancy on layer thickness, speed of growth, and reaction rate is investigated under irradiation within the framework of the model presented here. The result obtained shows that the layer thickness, speed of growth, and reaction rate increase strongly as the defect generation rate rises in the irradiated layers. It also shows the feasibility of producing a compound layer (especially in near-noble metal silicide considered in this study) at a temperature below their normal formation temperature under the influence of radiation.     

极性介质中醋酸乙烯酯的辐照引发分散聚合

用钴 60γ射线引发醋酸乙烯酯的分散聚合 ,通过选择各种极性溶剂体系 ,确立了醋酸乙烯酯在极性介质中稳定的分散聚合体系 .对异丙醇 水体系 ,聚合物分子量随剂量率的降低、稳定剂含量的增加、单体浓度的增大、反应温度的升高以及醇水比的降低而增加 .运用XPS、元素分析等表征聚合物粒子 ,及通过辐射接枝理论的分析 ,可以判断稳定剂所起的稳定作用主要是以物理吸附为主     

苯乙烯/马来酸酐和苯乙烯/甲基丙烯酸二甲氨基乙酯二元体系在聚四氟乙烯多孔膜上的γ辐射接枝

在氮气的氛围下用γ辐照的方法在聚四氟乙烯多孔膜上接枝苯乙烯 马来酸酐、苯乙烯 甲基丙烯酸二甲氨基乙酯二元单体 .并且研究了剂量、剂量率、溶液中单体的浓度和二元单体的摩尔比等条件对接枝率的影响 .探讨了两种单体的竞聚率对接枝率、接枝膜的组成及性能的影响 .结果表明 ,苯乙烯 马来酸酐二元体系对接枝率有协同效应 ,苯乙烯 甲基丙烯酸二甲氨基乙脂二元体系对接枝率表现为加合效应 .制备的二元接枝的聚四氟乙烯多孔膜可以进一步磺化来制备用于质子交换膜燃料电池的质子交换膜 .     

Radiation effects in high-disperse metal media and their application in powder metallurgy

Experimental and theoretical results showing up effects of metal powder radiation processing, such as powder grinding, chemical refinement, and changes in powder particle surface state, are discussed. It is shown that preliminary irradiation of metal powders leads to profound structural alterations at all further stages of their processing by conventional methods of powder metallurgy and eventually effects the properties of the resulting product.     

Synthesis and characterization of poly (n-butyl acrylate)-poly (methyl methacrylate) latex interpenetrating polymer networks by radiation-induced seeded emulsion polymerization

A series of latex interpenetrating polymer networks (LIPNs) were prepared via a two-stage emulsion polymerization of methyl methacrylate (MMA) or mixture of MMA and n-butyl acrylate (n-BA) on crosslinked poly(n-butyl acrylate)(PBA) seed latex using ⁶⁰Co γ-ray radiation. The particles of resultant latex were produced with diameters between 150 and 250 nm. FTIR spectra identified the formation of crosslinked copolymers of PMMA or P(MMA-co-BA). Dynamic light scattering (DLS) showed that with increasing n-BA concentration in second-stage monomers, the particle size of LIPN increased. Transmission electron microscope(TEM) photographs showed that the morphology of resultant acrylate interpenetrating polymer network (IPN) latex varied from the distinct core-shell structure to homogenous particle structure with the increase of n-BA concentration, and the morphology was mainly controlled by the miscibility between crosslinked PBA seed and second-stage copolymers and polarity of P(MMA-co-BA)copolymers. In addition, differential scanning calorimeter (DSC) measurements indicated the existence of reinforced miscibility between PBA seed and P(MMA-co-BA)copolymer in prepared LIPNs.     

Radiation-induced degradation of 4-chloroaniline in aqueous solution

The radiation-induced decomposition of 4-chloroaniline (4-ClA) was studied under steady-state conditions using aqueous solutions saturated with air, pure oxygen, N₂O, argon and argon in the presence of t-Butanol. Using HPLC-method, the initial G-values of the substrate degradation as well as of a number of radiolytic products were determined. The formation of aminophenols, chlorophenols, aniline and phenol in addition to chloride, ammonia, formaldehyde and mixture of aldehydes as well as carboxylic acids was studied as a function of absorbed dose. Based on the experimental data, probable reaction mechanisms for the degradation of 4-ClA by γ-rays and the formation of the identified products are presented.     

Microfiltration membranes with pH dependent property prepared from poly(methacrylic acid) grafted polyethersulfone powder

Poly(methacrylic acid) (PMAA) grafted polyethersulfone (PES) powder was prepared by γ-ray irradiation-induced graft polymerization. The existing of the PMAA side chains in the grafted powder was proved by FT-IR spectroscopy. Then, pH dependent microfiltration (MF) membranes were cast from PES-g-PMAA powder with different degree of grafting (DG) under phase inversion method. The contact angle, mean pore size and swelling behavior of MF membranes were measured. The morphology was studied and the water filtration property was also tested. The results showed that the mean pore sizes and filtration properties of MF membranes cast from PES-g-PMAA powder varied with pH. In the most variant case, the flux of acid solution was about four times as that of basic solution for the MF membrane cast from PES-g-PMAA with DG of 20.0%.     

双连续相微乳液辐射聚合制备多孔材料的研究

利用6 0 Co γ射线在室温下辐照双连续相微乳液体系以制备多孔聚合物材料 ,试图在控制多孔材料的微孔结构形态和减少微乳液聚合过程中的相分离方面做一些探索 .通过电导率的测量分析微乳液的结构类型 ,并确定微乳液的双连续相区域范围 .微乳液聚合后所得的样品的孔结构和聚合前的微乳液结构类型有关 ,扫描电镜和热重分析的结果表明双连续相微乳液在聚合时容易发生相分离 ,未必能够得到开孔结构的聚合物 .但适当控制聚合前微乳液的组成 ,如选择合适的水油比例、交联剂的用量和加入一些功能性单体 (如甲基丙烯酸或丙烯酸钠 ) ,可以有效地抑制相分离 ,调节所得聚合物的结构形态 .     

有机分子溶胀法对聚乙烯辐射交联机理的研究

聚乙烯在室温下几乎不溶于任何有机溶剂。所以,较低分子量有机化合物对聚乙烯辐射交联影响的研究受到很大限制。本文将具有端基双键的正-1-十六烯和相应的正-十六烷分别溶胀在固态聚乙烯中,观察了这两种较低分子量有机分子对聚乙烯辐射交联和不饱和度的影响。结果表明,分别溶胀在聚乙烯中的两种有机分子对聚乙烯的辐射交联有不同程度的抑制作用,对聚乙烯辐照后不饱和度的变化亦有明显影响,进一步证实了PE不饱和的端双键基Y型交联是聚乙烯辐射交联优先发生的主要方式。     

Adsorption behavior of urokinase by polypropylene film modified with amino acids as affinity groups

In order to prepare a new-type adsorbent with an affinity ligand, polypropylene films modified with amino acid groups such as -phenylalanine (Phe), , -Phe, -cysteine (Cys), and , -tryptophane (Try), were prepared by radiation-induced grafting of glycidyl methacrylate (GMA) onto polypropylene (PP) films and subsequent amination of poly-GMA graft chains. The physical and chemical properties of the GMA-grafted PP film and the PP film modified with amino acid groups were investigated by IR and XPS. The adsorption of urokinase for the PP films modified with four kinds of amino acid groups were examined under various conditions, such as the contents of the amino acid group and pH value. The adsorption of urokinase increased with the increasing content of the amino acid group. The adsorption of the PP film modified with four kinds of amino acid groups was in the following order: -Phe> , -Phe> , -Try> -Cys. The adsorption amounts of urokinase by the PP film modified with four kinds of amino acid groups at pH 7.4 was higher than that at pH 9.0.