共查询到20条相似文献,搜索用时 73 毫秒
1.
通过测定表面动态接触角研究了两亲性的苯乙烯/甲基丙烯酸嵌段共聚物(PS-b-PMAA)和苯乙烯/甲基丙烯酸(β-羟丙酯)嵌段共聚物(PA-b-PHPMA)的表面动态行为及温度、嵌段长度比等因素对其值的影响,讨论了聚合物表面当接触介质改变时链段或基团的再取向行为和表面性质。 相似文献
2.
作为一种传统的半导体,氧化锌在压电陶瓷、光电化学、光催化、发光器件以及气体传感器等方面具有广阔的应用前景,特别是氧化锌纳米粒子,由于其比表面积大、表面活性较高和对周围环境的敏感性,使其成为传感器研究领域中最有前途的材料,有关生物氧传感器和激光器的光电功能特性以及其能带结构的研究已有报道, 相似文献
3.
正、负离子碳氟-碳氢表面活性剂混合水溶液的表面活性 总被引:9,自引:0,他引:9
1 前言碳氟表面活性剂是目前所有表面活性剂中表面活性最高的一类 ,具有很多碳氢表面活性剂无法取代的特殊用途[1] 。但是碳氟表面活性剂由于合成困难 ,价格昂贵 ,实际应用受到限大限制。研究表明 ,通过碳氟表面活性剂与碳氢表面活性剂的复配 ,有可能减少碳氟表面活性剂的用量而保持其表面活性 [1] 。在所有表面活性剂混合体系中 ,正、负离子表面活性剂混合体系具有最强的协同效应 [2 ] 。但由于正、负离子表面活性剂混合溶液一般在很低浓度即形成沉淀 ,对碳氟表面活性剂更是如此。因此目前有关碳氟—碳氢混合表面活性剂的研究主要集中在同… 相似文献
4.
5.
非线性光学方法在电化学研究中的应用杨勇,林祖赓(固体表面物理化学国家重点实验室,厦门大学化学系361005)近年来,由于大功率脉冲型激光器的发展,非线性光学方法在表面科学及电化学中的应用逐步得到重视并有了较快的发展。不少的实验事实已经表明,由于其独特... 相似文献
6.
7.
8.
9.
本文应用LRS、TEM和脉冲吸附等技术分析了KCl助剂及其含量变化对MoO_3/γ-Al_2O_3催化剂表面钼物种的存在形式、聚集状态及其低温O_2、CO和300℃H_2吸附性能的影响.助剂钾和表面钼物种之间产生相互作用,导致其存在形式发生改变,促使氧化态样品中钼物种聚结及其相应硫化态样品中MoS_2微晶的长大.这种作用在K/Mo比0.65~0.8附近最大;当K/Mo比超过0.8时,γ-Al_2O_3表面出现KCl微晶,并有少量KCl和钼物种作用,影响了钾钼作用物种的形成,部分抑制了钼Mo(VI)的硫化或还原,使得硫化态样品中MoS_2的微晶晶型变差.由于MoS_2微晶聚集及少量和钼作用的KCl部分覆盖表面配位不饱和银位而致相应的O_2、CO和H_2吸附能力随钾含量增加而下降. 相似文献
10.
GaAs/AlxGa1—xAs量子阱电极/非水溶液界面性能的研究 总被引:1,自引:0,他引:1
用阻抗谱研究了晶格匹配型单、多量子阱GaAs/AlxGa1-xAs电极在二茂铁乙腈溶液中的界面性能。得到了空间电荷层电容及表面态电容与电极电位的依赖关系。空间电荷电容与量子阱电极的结构有关,而表面态电容则决定于电极的表面性质如表面氧化层及二茂铁的吸附。分析和讨论了表面态的能级,密度的分布,来源和作用。 相似文献
11.
S. K. Shakshooki S. A. Khalil A. S. M. Abuhamaira L. Szirtes Z. Pokó 《Journal of Thermal Analysis and Calorimetry》1992,38(7):1571-1577
The mixed metal phosphates were synthetized by the HF method, the resulting materials being crystalline. Thermal analysis revealed that they contain almost one mole of crystalline water per molecule unit. The mode of thermal decomposition of the samples was similar to those for crystalline phosphates containing only zirconium or titanium.
Zusammenfassung Die Mischmetallphosphate wurden mit der HF-Methode hergestellt, wobei man kristalline Substanzen erhielt. Die Thermoanalyse zeigte, daß sie fast ein Molekül Kristallwasser pro Moleküleinheit besitzen. Die Art der thermischen Zersetzung der Proben ähnelt der Zersetzung von kristallinen Phosphaten von nur Zirkonium oder nur Titan.相似文献
12.
A. Ubaldini C. Artini G. A. Costa M. M. Carnasciali R. Masini 《Journal of Thermal Analysis and Calorimetry》2006,84(1):207-211
The
aim of the present work is to study the thermal decomposition of the mixed
oxalates (Ce1–xGdx)2(C2O4)3·nH2O.
The mechanisms of decomposition of Ce and Gd oxalate are different, and mixed
oxalates behave in an intermediate way. Their dehydration stages are more
similar to those of Gd oxalate, as not all the molecules of water are equivalent
like the cerium oxalate. The decomposition leads to (Ce1–xGdx)O2–x/2. For x close to 0 or to 1 two solid solutions exist, while for the central
composition, the presence of a biphasic region can not be excluded. 相似文献
13.
Enthalpies of dilution and osmotic coefficients of the sodium dodecyl-sulfate (NaDS)-dodecyldimethylamine oxide (DDAO) mixtures in water have been measured at 25 and 37°C, respectively. From the enthalpies of dilution the apparent molar relative enthalpies L were calculated. The change of the L vs. total molality mt profiles with the mole fraction reflects the variation of the ionic character of the mixed micelles. From the osmotic coefficients the nonideal free energy G
2
ni
were calculated. By combining G
2
ni
with the partial molar relative enthalpies, the nonideal entropies TS
2
ni
were determined. At a given mole fraction, G
2
ni
and TS
2
ni
values are decreasing and increasing respectively, tending to become constant at high mt. The excess properties for the mixed micelle formation were evaluated as a function of the mixture composition at some mt. The profiles are compared with those obtained from thermodynamics of binary liquid mixtures and the regular solution theory. 相似文献
14.
A. G. Tozhiboev B. Tashkhodzhaev K. K. Turgunov N. I. Mukarramov Kh. M. Shakhidoyatov 《Journal of Structural Chemistry》2007,48(3):534-539
The structures of mixed crystals — solid solutions in the peganole-brompeganole system with molar ratios 0.72:0.28, 0.32:0.68, 0.10:0.90 and of pure peganole are determined by single crystal X-ray diffraction. It is shown that the solid solutions (mixed crystals) exist as three different phases. These crystal structures tend to form closed centrosymmetric dimers involving two molecules (probably different) joined by “anti-parallel” centrosymmetric hydrogen O-H...N(1) bonds. The development of this dimer is the cause of forming mixed crystals in the peganole–brompeganole system. 相似文献
15.
Thermogravimetric analysis was applied to the characterization of the porosity of silica gels. Results from thermogravimetric method are compared with those obtained from the nitrogen method. The consistency of the parameters characterizing the porous structure of silica gels derived from the data of various methods is satisfactory. 相似文献
16.
17.
A. L. Garcia-Ponce L. Moreno-Real A. Jimenez-Lopez 《Journal of inclusion phenomena and macrocyclic chemistry》1990,9(4):355-366
The layered mixed niobyl-vanadyl phosphate [(V0.l4Nb0.86)OPO4·2.7 H2O] can intercalate different amide molecules. In all cases, the amide I bands [v(CO)] of the original compound shift to lower frequencies, thereby indicating that the amide molecules interact with the layers probablyvia hydrogen bonds linking the coordinated water molecules to the metal atoms. To a lesser extent, primary amides show protonated molecules and tertiary amides show some molecules directly coordinated to the metals, as can be inferred from the bands appearing at 1732 and 1617 cm–1 in the IR spectrum, respectively. 相似文献
18.
Alexandre C. C. Rodrigues 《Reaction Kinetics and Catalysis Letters》2008,93(2):343-350
The gas-phase toluene oxidation was studied over platinum-containing mixed oxides derived from hydrotalcite-like compounds
with high specific surface area. Both the temperature of the reaction and toluene and oxygen initial concentrations proved
to influence toluene oxidation rate. Activation energy of 107 and 248 kJ/mol was found for toluene and oxygen, respectively,
with an oxygen dissociative model. 相似文献
19.
本文对SHA型吸附剂和活性白土混合吸附剂精制食用植物油进行了研究,筛选出二者最佳比例为4:2%,以及实验室条件下的最佳工艺:控制温度范围为120-140℃,振荡15min,离心分离15min,将脱色、脱酸、脱臭、脱过氧化物等步骤合一,大大简化了工艺过程。 相似文献
20.
A. La Ginestra P. Patrono A. Frezza C. Mancini M. A. Massucci S. Vecchio 《Journal of Thermal Analysis and Calorimetry》1993,40(3):1223-1232
Pure and mixed Ge and Sn hydrogenphosphates, prepared either by refluxing in 8M H3PO4 or by hydrothermal treatment at 180° or 300°C, have been characterized in terms of chemical composition and thermal behaviour and also tested as catalysts in the 1-butene isomerization, in order to correlate acidic properties with preparation method. Solid solutions for every composition in this system are formed only when using the refluxing method, as proved by X-ray and TG-DTA data. The hydrothermal treatments are strongly influenced by the hydrolysability of the Ge phosphate: in almost all the samples, where Ge was present, GeOHPO4 was identified on TG-DTA curves by the endothermic H2O weight loss at 700°–800°C. The acidic properties of the various materials decrease as GeOHPO4 content increases. 相似文献