Complexation of Titanium Alkoxides with Cis-2-butene-1,4-diol and Hydrolysis of Their Products

Reaction of Ti(OEt)₄ and Ti(OBu ⁿ )₄ with cis-2-butene-1,4-diol (B.diol-2H) in 1:1 molar ratio was studied at room temperature using the sol-gel process. ¹³C{¹H}- and ¹H-NMR data showed that all the B.diol-2H completely reacted with both titanium alkoxides. Each of the products was hydrolyzed by water. The new hydrolyzed products were characterized by ¹³C- and ¹H-NMR spectroscopy and Karl–Fischer Titration. Thermogravimetric and differential thermal analyses (TGA-DTA) of the hydrolyzed-products were also studied.     

钛白粉在溶剂型涂料中分散性的研究

本文从钛白粉表面性质出发，研究了钛白粉在溶剂型涂料中的分散机理，并分析了影响分散性的因素和提高分散性的途径，为改善钛白粉在溶剂型涂料中分散性提供了一定的理论基础。     

pH Effect on Titania-Phase Transformation of Precipitates from Titanium Tetrachloride Solutions

Precipitates in different structures were prepared by the hydrolysis of a TiCl₄ solution at room temperature and 70°C. The pH effect on titania-phase transformation was investigated. The original precipitate formed by the hydrolysis of titanium tetrachloride formed a gel-like structure at pH 4 with the addition of NH₄OH, which could be changed to essentially 100% rutile phase at 600°C. The rutile precipitates prepared at 70°C could be changed to mixed-phase product at pH 0.50 and total anatase phase at pH 3.13 and 5.15. Complete phase transformation from anatase to rutile occurred in the three samples at 700°C.     

计算机模拟溶剂对对苯二酚晶习的影响

针对苯二酚的单晶结构,采用BFDH和AE模型对对苯二酚的理论晶习进行了模拟,然后利用分子动力学模拟计算了对苯二酚各晶面在水溶液中与水分子的相互作用能,并利用修正的AE模型对水溶液可能出现的晶习进行了模拟计算,计算结果与实际晶习一致。     

四氢双环戊二烯异构化过程的溶剂效应

采用无水AlCl3为催化剂,考察了使用不同溶剂对桥式四氢双环戊二烯(endo-THDCPD)异构化为挂式四氢双环戊二烯(exo-THDCPD)过程中反应速率、反应转化率、收率、选择性及杂质生成量的影响。采用气相色谱对反应原料、产物及杂质进行定量分析。结果表明溶剂的使用对于异构化反应有显著的影响：甲苯作溶剂时对反应有很大的抑制作用,而1,2-二氯乙烷作溶剂时,则有明显改善,在催化剂浓度3％(wt)、最佳反应温度60℃条件下,反应结果：转化率97．73%、收率97.66％、选择性99．93％。同无溶剂反应时相比,最佳反应温度降低、产物中金刚烷生成量减少同时无焦油产生。实验中以原料endo-THDCPD为对象考察1,2-二氯乙烷作溶剂时的反应动力学,得到了动力学方程。     

Solvent Extraction of DNA with a Hydrolysable Double-chain Surfactant

Abstract

A cationic lipophilic surfactant with two hydrolysable groups, di(1-octadecyloxycarbonylmethyl)dimethylammonium chloride, was synthesized and solvent extraction of deoxyribonucleotide (DNA) into organic solution (isooctane/1-octanol) with it as an extractant was examined. Not only a forward extraction of DNA into the organic phase but also back extraction into the aqueous phase (pH > 9) at room temperature proceeded efficiently. The forward extraction is promoted by electrostatic interactions of the surfactant and DNA and the back extraction is exclusively caused by hydrolysis of the surfactant to a non-surfactant.     

影响钛白水解的因素探讨

文章主要介绍了钛液水解的基本原理和过程,以及影响钛白水解的关键因素,包括钛液本身的性质、组成和水解的操作条件等.     

聚合物-溶剂体系中能量对溶剂扩散的影响

The Vrentas-Duda free-volume theory has been extensively used to correlate or predict the solvent diffusion coefficient of a polymer/solvent system.The energy term in the free volume diffusion equation is difficult to estimate,so the energy term was usually neglected in previous predictive versions of the free volume diffusion coefficient equation.Recent studies show that the energy effect is very important even above the glass transition temperature of the system. In this paper, a new evaluation method of the energy term is proposed,that is the diffusion energy at different solvent concentrations is assumed to be a linear function of the solvent diffusion energy in pure solvents and that in polymers under the condition that the solvent in infinite dilution.By taking consideration of the influence of energy on the solvent diffustion,the prediction of solvent diffusion coefficient was preformed for three polymer/solvent systems over a wide range of concentrations and temperatures.The results show an improvement on the predictive capability of the free volume diffusion theory.     

钛白粉水解工艺优化的研究

对水解工艺从控制外加晶种的活性、温度、浓度、铁钛质量比、酸度及搅拌速度等指标进行优化,大大提高了水解质量。水解偏钛酸粒子的粒径更细,且粒度分布更优化了;水解率提高了,基本稳定在95%左右;水解后偏钛酸物料的水洗效果也明显优于以前。     

二氧化钛超细粉末的制备新方法

随着纳米科技的迅速发展，纳米材料已经越来越多的应用于国民经济、军事及其它高新技术的各个方面。目前，在液相中制备纳米二氧化钛等纳米颗粒现阶段已经较为容易。但是，制备经过高温灼烧的超细粉体材料仍然存在着粉体粒度不够小，分散性能差、生产设备复杂，生产成本较高等诸多缺点。特别是随着粉体粒径的减小，其分散性能越来越差。如何制备出分散性能好、粒径小，生产工艺简单的超细粉体材料仍然是一个需要不断研究的课题。本试验采用液相凝胶法，以低成本的四氯化钛和氨气为原料，经过煅烧，制备了纳米级别的二氧化钛微粉材料。产品粒径10nm左右．分散性能良好。     

溶胶凝胶法制备TiO2实验条件的考察

实验以钛酸正丁酯为前驱体,采用溶胶凝胶法制备二氧化钛。设计正交试验,考察水、乙醇、冰醋酸、pH值和凝胶温度对凝胶时间和状态的影响。对凝胶时间的影响程度依次为：pH值、乙醇量、凝胶温度、冰醋酸量、水量。确定溶胶凝胶法合成二氧化钛最佳条件为：pH值为2-3、乙醇的量22～28mL、凝胶温度为55～65℃、冰醋酸的量1．75～2．5mL、水的量2．0～2．5mL。     

硫酸溶液中钛水解物晶型的控制

对硫酸溶液中低钛浓度下钛水解产物晶型与水解条件的关系进行了研究.结果表明,通过调节硫酸钛溶液的加入速度和硫酸浓度,可控制水解物晶型.在100℃的2.5%(ω)硫酸溶液中,当硫酸钛溶液加入速度不高于2mL/h,主要生成金红石型TiO2;而当加入速度增至8mL/h或硫酸浓度增至不低于10%(ω)时,则主要形成锐钛矿型TiO2.水解速度较快的均相成核阶段较易生成锐钛型TiO2,而在晶核长大阶段,缓慢水解有助于形成酸性溶液中热力学上更稳定的金红石型TiO2.     

非质子溶剂凝胶法快速制备纳米TiO2

在非质子非极性溶剂体系中,用凝胶法快速地合成了纳米TiO2超微粒子。研究溶剂的变化对TiO2粒子的影响。结果表明,以苯为溶剂时,V(钛酸丁酯)∶V(苯)=4∶15,V(钛酸丁酯)∶V(H2O)=1∶1,热处理温度为400～600℃时,合成的纳米粒子平均粒径约5nm,对215～300nm内的紫外光具有很强的吸收。该法操作简单,溶剂能够回收利用,所得的纳米TiO2粒子团聚小,粒径分散均匀。     

Conversion Process of Strontium–Titanium Bimetallic Methoxyethoxide Precursor into SrTiO3 via Hydrolysis/Calcination

The conversion of a Sr–Ti bimetallic methoxyethoxide precursor into SrTiO₃ via hydrolysis and/or calcination was investigated. Hydrolysis with various water/metal molar ratios ( r _H; r _H= 0.5, 2, 4, 6, 8, 10) in tetrahydrofuran at reflux resulted in a decrease in the amount of the methoxyethoxyl groups, and the hydrolyzed products were soluble with r _H≤ 2. At r _H≥ 8, SrTiO₃ was crystallized without calcination. Both the hydrolyzed and unhydrolyzed precursors ( r _H= 0, 0.5, 2) were calcined in dry air at 550°–800°C. SrTiO₃ was crystallized on calcination at ≥550°C from amorphous materials with a considerable loss of carbon, which was present as both chars and carbonate ions.     

Influence of Several Metal lons on the Gelation Activation Energy of Silicon Tetraethoxide

The effects of nine metal cations (Li⁺, Na⁺, Mg²⁺, Ca²⁺, Sr²⁺, Cu²⁺, Al³⁺, La³⁺, and Y³⁺) on silica gel formation have been investigated by studying the hydrolysis and polycondensation of silicon tetraethoxide (TEOS) in the presence of metal nitrates. The influence of the water: TEOS mole ratio, metal ion concentration, and the reaction temperature has been investigated. The overall activation energy for gel formation has been determined from the temperature dependence of the time of gelation for each system. The activation energy for network formation is 54.5 kJ/mol. The gel formation time as well as the activation energy sharply increases in the presence of Cu²⁺, Al³⁺, La³⁺, and Y³⁺. In contrast, the presence of Li⁺, Na⁺, Mg²⁺, Ca²⁺, or Sr²⁺ lowers the gelation time but has no appreciable effect on the activation energy. This difference may be attributed to the participation or nonparticipation of the metal ions in the formation of the three-dimensional polymeric network during polycondensation. The concentration of metal ion (Mg²⁺, Ca²⁺, Y³⁺) or the water: TEOS mole ratio had no appreciable effect on the gelation activation energy. A simple test has been proposed to determine whether a metal ion would act as a network intermediate or modifier in silica and other glassy networks.     

溶剂对顺丁烯二酸酐含量测定的影响

顺丁烯二酸酐是一种重要的有机原料,对其含量的测定有很大意义.目前,文献上提到的顺丁烯二酸酐含量测定方法的误差较大.因此,研究了各种条件下测定顺丁烯二酸酐的含量.实验结果表明:用纯水、40 % DMF水溶液或40 %丙酮水溶液做溶剂时,都能够较准确测定顺丁烯二酸酐的含量,在有机体系中用40 %丙酮水溶液较纯水或40 %DMF水溶液好.     

二醋酸纤维素溶液中助溶剂的作用机制

利用旋转粘度计和气压式毛细管流变仪等研究了助溶剂对二醋酸纤维素 -丙酮体系溶液性能的影响 ,并就助溶剂的作用机理进行了探讨 ,认为主要是由于助溶剂与二醋酸纤维素大分子链形成氢健的作用所致。理论估测与实验值能很好吻合     

Effect of Crystalline Leucite on Porcelain Bonding on Titanium

The effect of elimination of crystalline leucite on porcelain bonding to Ti was studied. The thermal expansion coefficient of low-fusing dental porcelain was decreased by eliminating the crystalline leucite phase. As a result, minimal thermal mismatch and better bonding between Ti and porcelain were obtained.     

钛对耐硫变换催化剂性能的影响

利用常压微反色谱、程序升温还原（ＴＰＲ）等技术研究了钛对耐硫变换催化剂性能的影响，结果表明：（１）钛能明显提高耐硫变换催化剂的活性，尤其是在低于６２３Ｋ时活性提高最为明显；（２）工业侧流试验后，含钛样品的保留活性及活性保留率均高于Ｋ８－１１；（３）催化剂中添加助剂ＴｉＯ２后，能显著提高对原料气中Ｈ２Ｓ含量变化的适应能力，因此可以拓宽对原料气的选择范围，对工业生产有着十分重要的现实意义。