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本文合成了含酰胺基团和不含酰胺基团的两类Gemini阳离子表面活性剂,测定了其表面活性参数,研究了酰胺基团对表面活性剂的表面活性和聚集行为的影响。结果表明,酰胺基团提高了Gemini阳离子表面活性剂的临界胶团浓度,降低了胶团聚集数,增强了胶团微极性,增大了表面活性剂的饱和吸附量。 相似文献
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对纯镍及其表面离子注钇样品在1000℃空气中的恒温氧化和循环氧化行为进行了研究。用扫描电镜(SEM)和透射电镜(TEM)对氧化膜的表面形貌及结构进行了观测。研究表明离子注钇极大地提高了金属镍的抗氧化性能。此外,用声发射(AE)技术研究了氧化膜/基体界面上缺陷的分布情况,并用激光拉曼(Raman)谱对注钇引起的膜内应力变化进行了测量。结果表明,离子注钇降低了NiO氧化膜的生长速率,减小了表面NiO的晶粒尺寸,降低了膜内压应力水平。同时,离子注钇还减小了氧化膜/基体界面缺陷的平均尺寸和数目,因此,极大地提高了镍表面NiO氧化膜的粘附性和保护性。 相似文献
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Calibration of gel permeation chromatography was carried out to determine molecular weight and molecular weight distribution of the side-chains and homopolymer formed during grafting of cellulose acetate with acrylamide monomer using accelerated electrons. Polyacrylamide in side-chains and in homopolymer was found to be of very high molecular weight; the grafting event was found to be as low as 1–10 polyacrylamide chains per 103 cellulose acetate chains. 相似文献
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Proteins extracted from gluten of the bread wheat cultivar Fiorello 2 in the presence of 2-mercaptoethanol or dithiothreitol were separated by isoelectric focusing in a free solution in a pH 3-10 gradient containing 50% v/v 1-propanol or urea. The collected fractions were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in 10% gels (high and medium molecular weight glutenin subunits) and 16% gels (low molecular weight gliadins). The isoelectric focusing pattern of gluten polypeptides in 50% v/v 1-propanol was comparable to that obtained on two-dimensional gel electrophoresis, based on isoelectric focusing and polyacrylamide gel electrophoresis or nonequilibrium pH gradient electrophoresis and polyacrylamide gel electrophoresis. A similar isoelectric focusing pattern was also observed when 3M urea was used as solvent. New gluten polypeptides, similar in mobility to the high molecular weight subunits of glutenin were detected at acidic pH. 相似文献
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The effect of a low molecular weight nonionic surfactant and an acrylic associative thickener on the rheology of polyacrylamide in aqueous glycerol solutions under steady shear was experimentally investigated. The nonionic surfactant (Tween20), associative thickener (Acrysol TT935) and polyacrylamide (Separan AP30) underwent complex molecular interactions in solution as reflected by rheological measurements. The surfactant also interacted with the glycerol solvent. The addition of surfactant in aqueous glycerol solutions reduced the surface tension, as well as the solution viscosity, at low surfactant concentration. The solution viscosity went through a minimum at certain surfactant concentration, depending on the composition of glycerol/water mixture, before increasing again. Similar behavior was found when the surfactant was added to the polyacrylamide solution, except there was an initial increase in the viscosity before the reduction. The associative thickener, Acrysol TT935 (an anionic acrylic emulsion copolymer) exhibited a strong affinity with polyacrylamide in solution, as indicated by a sharp increase in the solution viscosity. The dilute polyacrylamide solution became highly elastic in the presence of either the nonionic surfactant on the associative thickener. A threestage model was proposed to describe the surfactant/thickener/polymer interactions. 相似文献
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Flocculation of kaolin particles by two typical polyelectrolytes: A comparative study on the kinetics and floc structures 总被引:1,自引:0,他引:1
Jianfeng Yu Dongsheng Wang Xiaopeng Ge Mingquan Yan Min Yang 《Colloids and surfaces. A, Physicochemical and engineering aspects》2006,290(1-3):288-294
The flocculation kinetics of kaolin particles induced by two polyelectrolytes is studied by using small-angle laser light scattering (SALLS). Two different methods, image analysis and SALLS, are used to calculated the fractal dimensions of flocs formed under different flocculation mechanisms. For a high charge density of polydiallyldimethylammonium chloride (PDADMAC), the initially flocculation rates are slow due to the quite low molecular weight. Smaller and more compact flocs are in the particle–particle connections, and restructuring of the flocs occurs in the flocculation process. With cationic polyacrylamide C498 of very high molecular weight and low charge density, however, the initially flocculation rates are much higher due to its rapid adsorption on kaolin particles, but it will take the adsorbed polymer a much longer time to reach equilibrium due to re-conformation. High potentialities of adsorption prevent the particles from entering the interior of the floc structure or rearrangement, which results in a more open floc structure. Different underlying flocculation mechanisms are evident for these two kinds of polyelectrolytes, in which charge neutralization is mainly involved for the low molecular weight and high charge density polymer of PDADMAC while polymer bridging is suggested to be the dominant mechanism for the high molecular weight polyelectrolyte of C498. 相似文献
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Factors influencing the in vitro release of bovine serum albumin (BSA) from poly(butylcyanoacrylate) (PBCA) nanocapsules, such as the pH value, BSA loading, the polymeric nanocapsule walls and protein molecular weight, were investigated in detail. The BSA release rate was affected by the degradation rate of the polymeric wall and protein loading. For low molecular weight proteins, the initial burst release was faster than that of high molecular weigh proteins and got to equilibrium quickly. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis results showed that BSA encapsulated within PBCA nanocapsules did not suffer covalent aggregation or fragmentation during the initial days of in vitro incubation. For nanocapsules prepared by interfacial polymerization in water-in-oil microemulsions, these findings were useful as a foundation for the development of nanocapsules with desired properties. 相似文献
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聚丙烯酰胺/柠檬酸铝胶态分散凝胶性质的研究 总被引:28,自引:0,他引:28
用低浓度不同分子量的部分水解聚丙烯酰胺( H P A M) 和柠檬酸铝制备了胶态分散凝胶( C D G) ,并用奥氏粘度计、超细粒度分析仪、岩芯流动实验对 C D G 的性质进行了研究.结果表明, C D G 的粘度比 H P A M 粘度低,粒径在450 ~520n m 之间.岩芯流动实验结果表明, C D G 能够使岩芯的流动阻力大幅度增加,且在岩芯中达到同样的流动阻力所需通过 C D G 的体积与形成 C D G 的 H P A M 的分子量、浓度及岩芯渗透率有关. 相似文献
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Jianping Gao Tong Lin Wei Wang Jiugao Yu Shaojun Yuan Shaomin Wang 《Macromolecular Symposia》1999,144(1):179-185
The chemical degradation of polyacrylamide(PAM) at low temperature in aqueous medium was initiated by peroxides. The degradation degree of the polymer rose with the reaction time. The degradation degree of PAM depended not only on peroxide characteristic but also on the concentration of polyacrylamide and potassium persulfate, degradation temperature and original molecular weight of PAM. The results showed that the order of degradation degree of PAM in three peroxides is K2S2O8 > K2S2O8 — Na2S2O3 > H2O2. The degradation degree of PAM grew as reaction temperature, molecular weight of PAM, concentration of potassium persulfate and PAM increased. 相似文献