共查询到20条相似文献,搜索用时 140 毫秒
1.
2.
3.
4.
5.
简易动态法测定液体饱和蒸气压的装置 总被引:5,自引:0,他引:5
测定液体饱和蒸气压的方法有静态法、动态法和饱和气体法。目前,国内大中专院校物理化学实验教材中多数采用静态法,虽然有些物理化学实验书[1,2]中,涉及动态法测定纯液体饱和蒸气压,但所用仪器和装置复杂,有的玻璃接头难以买到。我们设计了如下用动态法测液体蒸... 相似文献
6.
7.
8.
采用沸点仪测定了顺丁烯二酸酐和邻苯二甲酸二甲酯二元体系在4.00, 8.00和12.00 kPa下的等压气液平衡数据以及纯DMP组分饱和蒸气压数据, 将实验数据回归得到了纯DMP在417~525 K范围内的Antoine方程. 根据实验平衡温度、 压力和组成数据进一步回归得到NRTL方程参数, 推算出平衡气液相组成, 并利用UNIFAC方程对实验数据进行了预测, 其结果与沸点仪测定结果及NRTL拟合的结果基本相符. 相似文献
9.
应用弯曲界面存在的气液平衡条件和界面热力学方法,分析讨论了物理化学教材中开尔文公式的推导方法和过程,指出了存在的一些容易产生误解的问题。明确指出:等温下小液滴饱和蒸气压相对于平面液体饱和蒸气压的增大是由弯曲液面下液体的附加压力引起的,而不是界面自由能变化所致。并提出了一些教学建议。 相似文献
10.
液体的饱和蒸气压受外压的影响,根据外压对液体饱和蒸气压的影响公式可以推导出液滴、弯曲液面的开尔文公式。 相似文献
11.
大面积高质量石墨烯的制备对石墨烯电子特性及石墨烯基纳器件相关研究有重要意义。本文综述了近几年来衬底上制备石墨烯的相关实验以及衬底与石墨烯相互作用研究的重要进展。目前,采用化学气相沉积、外延生长等方法可在衬底表面上制备出较大面积、高质量的石墨烯材料。衬底与石墨烯相互作用和界面间晶格匹配、原子成键及电荷转移等密切相关,其对吸附石墨烯的几何结构、能带结构及电子特性等产生明显影响。实验与理论计算的结合可望加深衬底与石墨烯作用机理的理解,指导衬底上石墨烯制备及改性的进一步研究。 相似文献
12.
用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%. 相似文献
13.
表面活性剂与有机小分子作用不仅能提高表面活性剂的聚集能力,还能提高小分子的溶解度、稳定性等应用性能,因此研究二者之间的相互作用机理对于促进表面活性剂的发展和实际应用具有重要意义。本工作提出了一种利用功能有机小分子调控表面活性剂聚集行为,进而提高不稳定小分子自身稳定性的新策略。利用表面张力、紫外可见吸收光谱、荧光光谱、动态光散射、等温滴定量热和核磁共振技术研究了在p H为7.0时,叶酸分别与十二烷基硫酸钠(SDS)、十二烷基三甲基溴化铵(DTAB)、季铵盐Gemini 12-6-12和季铵盐线性三聚12-3-12-3-12四种表面活性剂之间的相互作用及其导致的叶酸光氧化降解性能的变化,结果表明,阴离子表面活性剂SDS抑制叶酸光氧化降解的效率较低,而阳离子表面活性剂都能够显著抑制叶酸的光氧化降解,且随着表面活性剂寡聚度的增加,抑制效果增强,所需表面活性剂的浓度显著降低,寡聚表面活性剂12-3-12-3-12的抑制效率高达96%。 相似文献
14.
Phase and structural relationships of the sulfur, selenium, and tellurium compounds of the 4d and 5d transition elements of groups IV to VII of the periodic system are discussed. Homologous elements behave very similarly with respect to the chalcogens, and this is particularly the case for niobium and tantalum, and for molybdenum and tungsten. However, zirconium, niobium, and molybdenum have a greater tendency towards formation of chalcogen-poor phases than their homologues hafnium, tantalum, and tungsten. Subchalcogenides are known only for zirconium and niobium. The number of phases and the tendency towards formation of solid solutions are considerably smaller among the tellurides than among the sulfides and selenides. The crystal structures of the telluride phases also differ from those of the sulfide and selenide phases of analogous composition. In addition, a review of the phase and structural relationships of the arsenic and antimony compounds of the 4d and 5d transition elements of groups V to VII is given. 相似文献
15.
16.
Thin films of incompatible polymer blends can form a variety of structures during preparation and subsequent annealing process. For the polymer blend system consisting of polystyrene and poIy(styrene-co-p-bromo-styrene), i.e., PS/PBrxS, its compatibility could be adjusted by varying the degree of bromination and the molecular weight of both components comprised, in this paper, surface chemical compositions of the cast and the annealing films were investigated by X-ray photoelectron spectroscopy (XPS) and contact angle measurement; meanwhile, surface topographical changes are followed by atomic force microscopy (AFM). In addition, substantial attention was paid to the effect of annealing on the morphologic variations induced by phase separation and/or dewetting of the thin film. Moreover, the influences of the molecular weight, Aw, as well as the brominated degree, x%, on the sample surface are explored systematically, and the corresponding observations are explained in virtue of the Flory-Huggins theory, along with the dewetting of the polymer thin film. 相似文献
17.
Gulnara Gaynanova Leysan Vasileva Ruslan Kashapov Darya Kuznetsova Rushana Kushnazarova Anna Tyryshkina Elmira Vasilieva Konstantin Petrov Lucia Zakharova Oleg Sinyashin 《Molecules (Basel, Switzerland)》2021,26(22)
This review focuses on key topics in the field of drug delivery related to the design of nanocarriers answering the biomedicine criteria, including biocompatibility, biodegradability, low toxicity, and the ability to overcome biological barriers. For these reasons, much attention is paid to the amphiphile-based carriers composed of natural building blocks, lipids, and their structural analogues and synthetic surfactants that are capable of self-assembly with the formation of a variety of supramolecular aggregates. The latter are dynamic structures that can be used as nanocontainers for hydrophobic drugs to increase their solubility and bioavailability. In this section, biodegradable cationic surfactants bearing cleavable fragments are discussed, with ester- and carbamate-containing analogs, as well as amino acid derivatives received special attention. Drug delivery through the biological barriers is a challenging task, which is highlighted by the example of transdermal method of drug administration. In this paper, nonionic surfactants are primarily discussed, including their application for the fabrication of nanocarriers, their surfactant-skin interactions, the mechanisms of modulating their permeability, and the factors controlling drug encapsulation, release, and targeted delivery. Different types of nanocarriers are covered, including niosomes, transfersomes, invasomes and chitosomes, with their morphological specificity, beneficial characteristics and limitations discussed. 相似文献
18.
多极性基有机添加物对非离子表面活性剂溶液雾点的影响 总被引:1,自引:0,他引:1
测定了甲酸、乙酸、草酸、甲醇、乙醇、丙醇、乙二醇、丙三醇和葡萄糖对非离子表面活性剂Triton X-100和Triton X-114水溶液雾点的影响。低级脂肪酸和醇能使雾点升高, 升高的程度随酸或醇的碳氢链的增长而增加。但若在增加分子碳氢链长或碳氢部分的同时引入更多的羧基或羟基, 则雾点升高的效应将受到抑制。当极性基数目较多时, 可导致雾点显著下降。 相似文献
19.
以α位(2,4-二特戊基)苯氧基邻苯二腈作为环合前体,制备了多种金属酞菁,产物经元素分析、紫外、红外、核磁氢谱等分析手段进行表征.并选择了部分酞菁进行溴化,其中着重研究了不同中心金属以及溴化对染料Q带吸收的影响.结果表明,酞菁染料的金属化对于其Q带吸收影响很大,多数染料金属化后会出现蓝移,而选择合适的条件进行溴化,可以使得金属酞菁的Q带吸收出现一定程度的红移,其中部分溴化金属酞菁的吸收波长与光信息产业中使用的近红外激光器很接近,具有潜在的实用价值. 相似文献
20.
A NOVEL APPROACH TO RHEOLOGICAL CHARACTERIZATION FOR THE GELATION IN POLYMER CRYSTALLIZATION 总被引:5,自引:0,他引:5
QingChen Yu-runFan QiangZheng 《高分子科学》2005,(4):423-434
The isothermal crystallizations of three kinds of commercial isotactic polypropylene have been studied by DSC and rheometric experiments, in a range of temperatures where the rate of crystallization is moderate. As the crystallization proceeds, volume contraction induces tensile force upon the parallel plates. The tensile force relaxed quickly in liquid states,but after a critical amount of the relative crystallinity, it starts to accumulate in the static test, that is, with the motionless parallel plates. A new method to determine the liquid-solid transition by the static tensile force is proposed and compared with two dynamic methods of detecting liquid-solid transition, that is, the power-law modulus theory and the yield modulus model. The tensile force method predicted considerably earlier transition than the dynamic methods, and the corresponding DSC data indicate relative crystallinity of larger than 0.2 at the transition times. The limitation of dynamic methods and other possible errors have been analyzed. While the dynamic methods are suitable for slow crystallization, the tensile force method is more appropriate for the crystallization of moderate rates. Moreover, it has the advantage of almost not disturbing the crystallizing materials before the transition. 相似文献