共查询到20条相似文献,搜索用时 0 毫秒
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Bryan D. Vogt Christopher L. Soles Hae-Jeong Lee Eric K. Lin Wen-li Wu 《Polymer》2005,46(5):1635-1642
Moisture absorption into ultrathin poly(vinyl pyrrolidone) (PVP) films with varying thickness was examined using X-ray reflectivity (XR) and quartz crystal microbalance (QCM) measurements. Two different surfaces were used for the substrate: a hydrophilic silicon oxide (SiOx) and a hydrophobic hexamethyldisilazane (HMDS) treated silicon oxide surface. The total equilibrium moisture absorption (solubility) was insensitive to the surface treatment in the thickest films (≈150 nm). However, strong reductions in the equilibrium uptake with decreasing PVP film thickness were observed on the HMDS surfaces, while the SiOx surface exhibited thickness independent equilibrium absorption. The decreased absorption with decreasing film thickness is attributed a depletion layer of water near the polymer/HMDS interface, arising from hydrophobic interactions between the surface and water. The diffusivity of water decreased when the film thickness was less than 60 nm, independent of the surface treatment. Changes in the properties of ultrathin polymer films occur even in plasticized films containing nearly 50% water. 相似文献
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采用单因素实验法,以聚合物在皮革鞣制工艺中应用后坯革收缩温度的增加量为考察指标,从单体配比、单体占总体系的质量分数、反应体系pH、引发剂用量、反应时间等因素对聚二烯丙基二甲基季铵盐/丙烯酰胺(PDM/AM)聚合的合成工艺进行了优化。结果表明:当n(DM)∶n(AM)=1∶3,单体占总体系的质量分数为30%,反应体系pH=5,引发剂用量为4%,反应5 h时,聚合物的产率达91.27%,特性黏度为31.54 mL/g,应用于皮革鞣制工艺中鞣制效应较好。通过红外光谱和X-射线衍射分析等手段对PDM/AM的结构进行表征,结果表明,丙烯酰胺与二烯丙基二甲基氯化铵成功地发生了聚合。 相似文献
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This paper introduces a set of new concepts related to the macromolecular design and to the practice in the realm of lamination by photografting, with experimental studies of the synthesis, structure, and performance of various systems, including valence bond adhesion of the organic polymeric materials, hyperbranched macromolecules rooted to the surface of organic substrates, macromolecular networks rooted on and bridged between two organic substrates, and a synthetic route combining primary and secondary photografting processes for the preparation of supermolecular architectures. In successful photolamination experiments based on these ideas, hyperbranched macromolecules of large size (10–20 μm) were obtained after initiation with aromatic ketones, which undergo a photoreduction reaction. A range of different organic polymeric films have been laminated. T-peel tests show most of the laminates broke inside the substrates and not at the interface between adhesive and substrate. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1723–1732, 1997 相似文献
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Ellen Raphael 《Electrochimica acta》2010,55(4):1455-7
New types of polymer electrolytes based on agar have been prepared and characterized by impedance spectroscopy, X-ray diffraction measurements, UV-vis spectroscopy and scanning electronic microscopy (SEM). The best ionic conductivity has been obtained for the samples containing a concentration of 50 wt.% of acetic acid. As a function of the temperature the ionic conductivity exhibits an Arrhenius behavior increasing from 1.1 × 10−4 S/cm at room temperature to 9.6 × 10−4 S/cm at 80 °C. All the samples showed more than 70% of transparency in the visible region of the electromagnetic spectrum, a very homogeneous surface and a predominantly amorphous structure. All these characteristics imply that these polymer electrolytes can be applied in electrochromic devices. 相似文献
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消泡剂的消泡机理及其在皮革涂饰剂中的应用 总被引:1,自引:0,他引:1
本文就消泡剂的消泡机理进行了探讨,并考察了不同种类消泡剂的消泡效果,通过实验测定优选了适宜的消泡剂,并确定了其最佳用量。结果表明,聚醚改性聚硅氧烷类迪高消泡剂消泡效果较好,其适宜用量为3‰。 相似文献
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Light reflection at polymer-coated electrodes is studied for polyaniline, poly(o-methylaniline), and poly(o-methoxyaniline). Reflected light intensity is found to be affected greatly by the applied potential for the two reasons: one is absorption of light due to coloring of the oxidized polymer film and the other is light scattering which is concerned with a polymer chain conformation upon oxidation. A new method based on the potential dependence of light reflection is proposed for studying kinetics of conformational changes of polymer chains. The rate constants evaluated are in the range of 0.05-8 s−1 at room temperature, depending on the sort of polymers, the film thickness, and pH of the solution. Irrespective of the sort of polymers, the increase in film thickness or solution pH leads to the decrease of the rate constant. It is found that a film morphology has a significant effect on the rate constant, as confirmed by a comparison of rate constants observed with polyaniline films grown at different rates. 相似文献
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介绍了采用添加复合助剂的方法对常规ADC进行化学改性的情况。考察了抑制剂在低温段的抑制发泡效果和促进剂在高温段的促进发泡效果,确定了在常规ADC中加入2%~6%的草酸为抑制剂和加入适量促进剂的发泡剂配方,经筛选并在实际生产中应用,满足了PVC压延人造革工艺的新需求。 相似文献
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以氧乐果为模板分子,采用原位逐步聚合法制备了具有良好识别性能的分子印迹聚合物(MIPs),考察了氧乐果、敌敌畏及甲胺磷在氧乐果分子聚合物上的选择性分离富集特性.用氧乐果分子聚合物固相萃取了蔬菜和天然水中的氧乐果.结果表明,聚合物对模板分子产生了印迹效应,对氧乐果有明显的选择性.流速为1.0 mL/min,进样量为20 μL. 相似文献
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The effects of polymer impregnation, moisture, and lubricant oils on the complex modulus of the grain layer of leather have been studied. The impregnated materials were prepared by introducing a mixture of polyurethane oligomer and vinyl monomers into the grain layer and polymerizing by electron-beam irradiation. Synergism was observed in the interaction of the components of the system and analyzed in terms of the adhesion of the polymer to the collagen fibers. 相似文献
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综述了目前在我国防水涂料市场迅猛发展的聚合物水泥基复合防水涂料及分析其配方设计基理,材料性能特点,并探索拓宽其在工程应用中的新领域。 相似文献
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亲水性高分子磁性微球的合成和应用研究 总被引:1,自引:1,他引:1
对近年来国内外有关亲水性高分子磁性微球的研究成果和发展现状进行了综述,具体讨论了包埋法、单体聚合法及原位法等常用的合成制备方法及其优缺点,指出反相(微)乳液聚合是制备亲水性聚合物微球的有效方法。分析了亲水性高分子磁性微球在酶固定化和实现靶向给药等方面的应用及存在的问题,对磁性微球的发展前景进行了展望。 相似文献
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Altering the surface wettability by external stimulation has received great attention recently. While different stimuli, such as temperature, pH, etc. can be applied for this purpose, light combines several advantages. It is a contact-free stimulation, which can be applied locally, thereby allowing a versatile patterning. This review article summarizes recent developments in the area of polymers that allow a light-induced change in surface wettability. For this purpose, different photochromic dyes have been incorporated into polymers, which enable a photo-isomerization upon light irradiation resulting in a change in polarity. Several examples based on azobenzene or spiropyran will be discussed, but also some more exotic examples, such as those based on salicylideneaniline, will be highlighted. The different approaches how to apply these photochromic dyes to various surfaces are presented and discussed. Additionally, the combination with other stimuli-responsive moieties will be explored and the paper will be concluded by mentioning the remaining challenges and by providing a future perspective. 相似文献
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国内有机高分子絮凝剂的开发及应用 总被引:21,自引:3,他引:21
介绍了我国有机高分子絮凝剂研究开发的历史与现状及其在水处理中的应用,内容涉及合成有机高分子絮凝剂,化学改性天然高分子絮凝剂和微生物絮凝剂;介绍了我国有机高分子絮凝剂的产业现状,生产技术水平及国内外差距,同时指出,随着水资源短缺日趋严重和环保法规的日益强化,有机高分子絮凝剂在水处理中的应用将迅速增加。 相似文献
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Development of polymer films by the coalescence of polymer particles in powdered and aqueous polymer-modified mortars 总被引:1,自引:0,他引:1
This paper evaluates and compares the coalescence of polymer particles (continuous polymer films formation) in powdered polymer-modified mortars (PPMMs) and aqueous polymer-modified mortars (APMMs). Polymer-modified mortars (PMMs) using various redispersible polymer powders (powdered cement modifiers) and polymer dispersions (aqueous cement modifiers) were prepared by varying the polymer-cement ratio (P/C) and were tested for the characterization of polymer films using a scanning electron microscope (SEM) after curing for 28 days. It is concluded from the test results that mortar constituents of unmodified mortar (UMM) are loosely joined with each other due to the absence of polymer films, thus having a structure with comparatively lower mechanical and durability characteristics. By contrast, mortar constituents in PPMMs and APMMs are compactly joined with each other due to the presence of interweaving polymer films, thereby forming a monolithic structure with improved mechanical and durability characteristics. However, the results make obvious the poor coalescence of polymer particles or development of inferior quality polymers films in PPMMs as compared to that observed in APMMs. Moreover, PPMMs show less uniform distribution of polymer films as compared to that in APMMs. Different powdered cement modifiers have different film-forming capabilities. However, such difference is hardly recognized in aqueous cement modifiers. The polymer films in PPMMs and APMMs may acquire different structures. They may appear as mesh-like, thread-like, rugged, dense or fibrous with fine or rough surfaces. Development of coherent polymer films is not well pronounced at a P/C of 5% in PPMMs, whereas sometimes coherent polymer films are observed at a P/C of 5% in APMMs. At a P/C of 10% or more, fully developed, coherent polymer films are observed in both PPMMs and APMMs. 相似文献
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高聚物流变学的原理、发展及应用 总被引:5,自引:0,他引:5
综述了高聚物流变学的基本原理、发展、测试方法;介绍了流变分析的目的、应用和我国流变学发展所存在的 问题,指出我国流变学研究任重道远。 相似文献
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Emulsions of polyethylacrylate using sodium dodecylsulfate, cetylpyridinium chloride or nonylphenol ethoxylate as anionic, cationic and nonionic emulsifiers were prepared and the polymer deposition on metal panels in presence of an acid and an oxidizing agent was studied. Homogeneous films are formed within limited concentration ranges of the reactants. Diluted hydrofluoric acid and diluted hydrogen peroxide are useful components. Instead of a chemical oxidant a potential of 250 to 500 mV or more may be applied. The iron ion content of the film was determined by atomic absorption spectroscopy. A ratio of iron to emulsifier of 4.1 : 1 was found. The distribution of iron in film cross-cuts by scanning electron microscopy using the energy dispersive technique shows a high iron concentration near the metal interface and a sharp drop towards the film surface. In the outer third of the film the ratio iron to emulsifier is nearly 1 : 1. By adding iron salt solutions to polyethylacrylate emulsions the coagulation point was determined and a ratio iron ion to emulsifier of 1 : 1.2 was found in the coagulate. Steel panels were coated as well as phosphated steel or zinc but no film formation appeared on aluminum. 相似文献