Oxidative degradation of polyglycols by the Ruff’s system in the aqueous solutions

We have studied oxidative degradation of polypropylene glycol and polyethylene glycols of varied molecular mass induced by hydrogen peroxide in the presence of iron(III) ions. At pH 3, the process is accompanied by aggregation of iron hydroxides and occurs in the microheterogeneous system. In the cases of high-molecular substrates, the oxidation is accompanied by decrease in the polymer globulas size due to the degradation of the polymer chain.     

聚丙烯膜光氧化过程中表层光氧化产物的X-射线光电子能谱(XPS)的研究

本文用X-射线光电子能谱(XPS)研究了聚丙烯膜表层的光氧化产物,得出几种主要氧化产物的相对含量随氧化时间变化的规律并将其与缸外光谱所测结果及文献报道的相比较,证明膜表层光氧化和膜整体光氧化规律有所不同。根据实验结果提出了反应机理。     

Polypropylene composites filled by magnesium hydroxide coprecipitated with foreign ions

Rod‐like magnesium hydroxide (MH) particles were prepared via coprecipitation of the magnesium salt with foreign ions, such as copper(II), zinc(II), iron(III), and nickel(II). Flame retardant polypropylene (PP) composites were fabricated using these particles. The microstructure, flame retardation, mechanical properties, thermal behavior, and oxidation‐induced temperature were characterized. It was found that foreign ion compounds increased the flame retardancy. MH containing a zinc compound presented a similar performance as that of neat MH. The presence of a copper compound decreased the thermal behavior and mechanical properties of the flame retardant composite, while iron and nickel compounds brought some improvements. In addition, the thermal degradation mechanisms of the flame retardant composites were investigated by Fourier transform infrared (FTIR) spectroscopy at different temperatures. Copyright © 2008 John Wiley & Sons, Ltd.     

The Preparation of a Novel Polymer Film Based on Salicylaldoxime and its Influence on Aqueous Copper Electrochemistry

Abstract

The metal complexing ligand salicylaldoxime was electropolymerised onto platinum electrodes and the resulting film characterised by reflectance FT-IR spectroscopy. The modified electrode response to aqueous iron, copper, cobalt and lead ions was investigated with the iron(III) and copper(II) ions showing significantly altered electrochemistry. The response of the modified electrode towards aqueous copper ion was found to be directly proportional to copper concentration with little interference from lead ions. The retention of copper ions, film stability and the nature of the film action are discussed along with its potential use in sensor construction.     

Accelerated degradation of polypropylene by amosite asbestos

The use of differential scanning calorimetry and themogravimetric analysis showed that the accelerated oxidative degradation of polypropylene in the presence of amosite asbestos can be attributed to the catalytic decomposition of peroxides by iron and to air trapped in the fibre bundle.     

泡压-滤速法研究聚丙烯微孔膜的孔径及其分布

膜科学与膜技术作为新兴的材料科学分支之一,在国民经济中发挥着越来越重要的作用．近年来,高分子微孔膜的研究与应用正引起人们日益增长的关注．采用双轴拉伸方法制备的聚丙烯微孔膜同时具备了良好的力学性能和透过性能［１］,克服了单轴拉伸方法各向异性的缺点,是一...     

PP-SBS共混物光氧化降解的研究

和橡胶类树脂进行共混是聚丙烯(PP)改性的重要途径之一,共混有橡胶组分的PP改性树脂在其力学性能获得改进的同时,其老化性能必然也有一定的变化,我们用红外光谱方法研究了聚丙烯和苯乙烯-丁二烯星型嵌段共聚物的共混物(PP-SBS)的光氧化降解行为。     

An Auger Electron Spectroscopic Study of Ion and Plasma Etching of Thin Films Obtained by Plasma Activation of the Microdroplet Products of Thermal Degradation of Solid Polypropylene

The matrix properties of films obtained by plasma-enhanced deposition of the microdroplet products of thermal degradation of solid propylene (PEPP) were studied. The sample thickness was 120 nm, and the volume fraction of the dense phase was 10%. The rates of ion sputtering and the rates and some features of etching of the PEPP films at various plasma parameters were determined from the concentration profiles of the basic film-forming element (carbon) as obtained by Auger electron spectroscopy (AES) in combination with layer-by-layer sputtering by argon ions. It was shown that the films were highly uniform over the entire film depth down to the substrate. The oxygen concentration on the sample surface and over the film depth were determined after the plasma etching of the film in the residual air (the depth of penetration and formation of oxygen-containing groups did not exceed 30 nm). The alternation of interference colors on the PEPP surface observed in scattered light during the plasma etching was described. Comparison of the results obtained with the data for initial polypropylene made it possible to conclude that the matrix forming the basis of the PEPP coatings (90%) can be treated as a polymer-like structure.     

Photo-Fenton degradation of resorcinol mediated by catalysts based on iron species supported on polymers

Novel Fe supported catalysts were prepared by immobilizing iron species on commercial polyethylene via three different methods: (1) acidic pre-treatment of the polyethylene followed by impregnation in aqueous Fe(NO₃)₃, (2) TiO₂ photo-catalytic pre-treatment of the polyethylene followed by forced hydrolysis of Fe(NO₃)₃, and (3) direct photo-Fenton attack with concomitant iron deposition on the polyethylene surface. The last method required soft conditions and led to the most photo-active Fe–polyethylene film. With this material, at a non-adjusted initial pH of 5.6 in the presence of H₂O₂, total degradation and 50% of resorcinol mineralization were observed in 40 and 60 min, respectively. Photo-Fenton functionalization/Fe-deposition process was also applied to polypropylene, high-impact polystyrene, and polymethylmethacrylate films. The efficiencies of all the prepared heterogeneous photo-catalysts were similar to that of an homogeneous photo-Fenton system containing the same amount of Fe^3+/2+ that leached during “heterogeneous” processes. That demonstrated than in our systems mainly homogeneous photo-Fenton reactions were responsible for the resorcinol degradation. The photo-catalytic activity observed for the Fe/polymer was a function of the specific polymer capacity to release the initially deposited iron into the solution.     

聚丙烯膜表面光接枝聚合

对聚合物表面进行接枝聚合是一种有效的材料改性方法。近年来,S.Tazuke,Y.Ogiwara,高志民等人做了一些用紫外光引发接枝方面的工作,获得了较满意的结果。为提高聚丙烯(简称为PP)膜的光稳定性,我们研究了将一种受阻胺类光稳定剂,甲基丙烯酸2,2,6,6-四甲基哌啶醇酯(简称为MTMP)光接枝到PP膜表面的聚合过程。     

薄膜用聚丙烯树脂熔融态PVT行为的研究

利用PVT 10 0分析仪对 5种不同牌号的双向拉伸用聚丙烯 (BOPP)树脂的压力 体积 温度 (PVT)特性进行了测定 ,并利用Tait方程法得出BOPP熔体的热膨胀系数 (α)随温度和等温压缩系数 (β)随压力的变化关系 .研究结果表明 ,在相同条件下 ,牌号为S2 8C的BOPP熔体的热膨胀系数、等温压缩系数和结晶熔融温度分别低于其它牌号 ,因此 ,我们推断S2 8C在冷片形成过程中的体积形变较小 ,可避免由于收缩产生的模片表面缺陷 ,进而减少在后续双向拉伸过程中的破膜现象     

STRUCTURAL FEATURE AND EXCHANGE KINETICS OF CARBOXYLATED POLYPROPYLENE ION EXCHANGE RESIN

The present article deals with the exchange process of bivalent metal ions, such as Zn~(2+), Cd~(2+) and Hg~(2+), etc., taken up by non-crosslinked earboxylated polypropylene (CPP) resin. The control factor of the exchange rate deduced from the kinetic data is governed basically by the chemical reaction rather than the mass transfer effect particle diffusion and/or liquid film diffusion. In solution, all the graft chains in the outer shell of a CPP resin could form a "quasi-macromolecular solution" domain. This opinion further demonstrates the structural pattern of CPP resin proposed in earlier paper.     

黑色微弧氧化膜的制备及其表征

利用二次微弧氧化法,通过在磷酸盐体系的电解液中添加柠檬酸铁,在AZ40M镁合金基底表面成功制备了黑色的微弧氧化膜层。并利用扫描电子显微镜（SEM）、能谱仪（EDS）、X射线衍射（XRD）和X射线光电子能谱（XPS）分别对黑色膜层的形貌和成分组成进行了表征,探讨了黑色微弧氧化膜层的形成过程及机理。结果显示,黑色膜层的主要成分为氧化镁,同时伴随着一定量的铁氧化物,包括四氧化三铁、氧化亚铁和单质铁。因此镁基底表面黑色膜层的形成可归因于柠檬酸铁中的铁离子在成膜过程中参与反应形成了黑色的四氧化三铁、氧化亚铁和单质铁混合物,并均匀地沉积在氧化膜中。     

掺杂金属离子改性的TiO2薄膜光催化剂的研制

采用溶胶-凝胶法制备TiO2薄膜光催化剂，着重考察了掺杂铈、镧、钨等金属离子改性的TiO2薄膜的光催化活性，研究了其紫外-可见光透过性能，甲基橙水溶液的光催化降解实验表明：掺杂铈、镧、钨三种金属离子后，TiO2薄膜的光催化活性均有不同程度的提高，最佳掺杂浓度分别为3．0％、1．0％、0．5％，其中掺杂铈的TiO2薄膜光催化活性最高。     

Radiation effects on polymer materials in radiation sterilization of medical supplies

Radiation degradations of polypropylene were studied by measuring chemiluminescence of the irradiated samples. The chemiluminescence emitted by recombination of peroxy radicals were found to increase with increasing dose, reflecting degree of oxidation of polymers. The degradation of PP may be attributed mainly to the oxidation, since the degradation of PP irradiated in air were markedly larger than that in vacuo. It was found that degree of oxidation of EB-irradiated PP was only one-half that for γ-ray-irradiated one. And also the degree of oxidation was found to be very high at the surface area of the film where oxygen can diffuse during irradiation and decrease sharply with increasing depth from the surface.The degradation during storage after irradiation were estimated by the decay curves of chemiluminescence. The degradation during storage occurred at earlier stage up to three months, while in later stage, it hardly proceeded. The degradation of EB-irradiated samples during storage was much smaller than that found in gamma rays irradiation. Irradiation of 2.5 Mrad with EB caused degradation only during storage. It was suggested that the degradation during storage depends on the degree of radiation oxidation. Both degradations, during irradiation and during storage after irradiation, caused by EB irradiation were also found to be smaller than those by γ-rays. The relationship between radiation degradation and degree of crystallinity of polypropylene was also discussed in this paper.     

Degradation of polyethylene containing ferric salt and starch

The degradation of polyethylene containing four different ferric salts was compared, using remaining percentage elongation at break as a parameter; and the degradation process was also evaluated with carbonyl index, or with the formation and concentration of hydroperoxide groups. Starch can act as a synergist during the photodegradation of ferric contained PE film. X-ray photoelectroscopy analysis shows that part of ferric ions turned into ferrous ions during the degradation process because of the redox reaction of ferric ions with oxygen. When stabilizer was added, the changes from ferric ions to ferrous ions decreased. If the PE samples were exposed to high pressure mercury lamp in the atmosphere of nitrogen gas, the absorption peaks of carbonyl group was not found in IR spectra after several days exposure.     

添加剂对电沉积二氧化铅阳极性能的影响

本文研究了各种添加剂对电沉积二氧化铅阳极性能的影响,结果表明卤素离子和过渡金属离子对制备二氧化铅阳极的形貌和性能有很大影响,实验发现以氯离子和铁离子为添加剂制备的二氧化铅阳极用于电解析出臭氧时,其活性和稳定性明显改善。     

Anodic dissolution of iron microparticles in chloride-containing acetate buffer electrolytes studied by elimination voltammetry

Elimination voltammetry with linear scan (EVLS) was used for the study of the anodic dissolution process of iron microparticles immobilized on paraffin-impregnated graphite electrode. This process was investigated in acetate buffer solutions in the range of pH 4 to 6 and the effect of chloride ions was evaluated. It was found that the anodic dissolution process of iron powder proceeded in two peaks with different pH and KCl-dependent characterizations. Both the more negative process at about ?300 mV and the positive process at about 1,200 mV are influenced by chloride and hydroxyl ions. Chloride ions incorporate into the intermediate species and form more soluble species in the passivation layer, leading to its degradation. Detailed information about the processes was provided by the EVLS functions conserving diffusion current components. The mechanism of anodic dissolution of iron powder in acetate solutions representing passive ions and chloride ions appearing in the role of corrosion activators was discussed.     

GRAFT COPOLYMERIZATION OF ACRYLAMIDE ONTO POLYPROPYLENE FILMS BY PLASMA TECHNIQUE

The graft copolymerization of acrylamide onto polypropylene (PP) Film was carried out by using a capacitively coupled rf plasma apparatus with external plate electrodes. The relationship between the surface structure of the Ar plasma-treated PP films and the extent of grafting of acrylamide on the films was studied through observing the effects of discharge power and exposure time on the relative content of free-radical on the film surface. Meanwhile, the wettability and surface energy of the PP film were measured.