纳米二氧化钛粉体制备条件的探索

以钛酸丁酯为前驱体,采用溶胶-凝胶法制备纳米级二氧化钛微粒。对溶胶、凝胶形成的不同条件进行了试验。水解时应将水用乙醇稀释再对钛酸丁酯进行水解;pH在2～3时产生的凝胶较为均匀;溶剂乙醇与前驱体钛酸丁酯的用量比例n（乙醇）︰n（钛酸丁酯）=5︰3较为理想;生成凝胶的合适温度为35～40℃。     

溶胶—凝胶法制取超细TiO2粉末

本文研究了在以钛酸丁酯为原料，采用溶胶－凝胶法制取超细ＴｉＯ２粉末时，生成稳定凝胶的条件，并考察了在干凝胶热处理过程中，ＴｉＯ２颗粒的化学变化规律。     

超细二氧化钛的合成研究

利用溶胶－凝胶法合成超细ＴｉＯ２。采用多因素正交设计法，分别就溶剂，抑制剂，原料配比，搅拌速度，滴加速度，反应总和料量和反应器尺寸等工程因素对反应时间，产品收素和粒子尺寸的影响进行了讨论。筛选最佳工程条件为：反应器的高径比为２～３，选用釜式反应器，搅拌速度为４５０转／分，滴加速度为１２ｍｌ／ｍｉｎ该条件下可以得到平均粒径介于（８～２５）ｎｍ球状超细ＴｉＯ２。     

溶胶-凝胶法制备纳米二氧化钛的工艺条件优化

以钛酸丁酯为原料,采用溶胶-凝胶法制备纳米二氧化钛,探讨了钛酸丁酯的用量、钛酸丁酯与醋酸的体积比、钛酸丁酯与乙醇的体积比、煅烧温度、煅烧时间等对溶胶-凝胶法的影响,得出了制备纳米二氧化钛的最佳工艺条件。结果表明,制备二氧化钛的最佳工艺条件为:钛酸丁酯的用量为10mL,钛酸丁酯与醋酸的体积比为2∶1,钛酸丁酯与乙醇体积比为1∶3,煅烧温度为500℃,煅烧时间为2h。对最佳工艺条件下制备的二氧化钛进行XRD表征,二氧化钛的白度平均值为92.2;粒径平均值为18.5nm,粒径小于20nm。     

溶胶-凝胶法制备纳米二氧化钛的工艺研究

以钛酸丁酯为主要原料,采用溶胶-凝胶法制备纳米二氧化钛。通过对溶胶-凝胶法中各个主要影响因素的考察,得到制备纳米二氧化钛材料的优化工艺条件为:配制无水乙醇与水的混合液,并调节pH=2～3,缓慢加料;钛醇盐与水的摩尔比为2～4,乙醇与钛醇盐摩尔比为6～8,溶胶体系pH=2～3,水解成胶化温度为25℃～30℃。     

快速溶胶—凝胶法制备SiO2气凝胶的研究

以正硅酸乙酯（TEOS）为原料，以乙醇为溶剂，以盐酸和氨水为催化剂，用溶胶-凝胶法制得了SiO2气凝胶，大大加快了溶胶-凝胶的反应速率，使得凝胶时间减少至几分钟甚至于更短，TEM测试结果表明所制备的SiO2气凝胶具有纳米多孔结构（骨架颗粒为80nm)实验对溶胶-凝胶过程在不同条件下进行了研究。并对其凝胶过程作了初步探讨。得出了最佳工艺条件。     

化学络合法在溶胶—凝胶过程中的应用

在利用溶胶－凝胶技术制备先进玻璃及陶瓷时，经常碰到诸如这样一些问题：金属醇盐先驱体在醇中的溶解度小；反应活性大，易生成沉淀；而且一些醇盐很难直接买到。化学络合物方法可以克服这些缺点。本文阐述了添加络合剂的络合方法在溶胶－凝胶上的应用，包括如下几个方面：（１）改变一些醇盐的溶解度，使之溶解在醇溶剂中；（２）控制先驱体的反应活性；（３）变非醇盐先驱体为醇盐先驱体；（４）合成有机－无机复合材料；（５）通     

化学络合法在溶胶－凝胶过程中的应用

在利用溶胶－凝胶技术制备先进玻璃及陶瓷时，经常碰到诸如这样一些问题：金属醇盐先驱体在醇中的溶解度小；反应活性大，易生成沉淀；而且一些醇盐很难直接买到。化学络合物方法可以克服这些缺点。本文阐述了添加络合剂的络合方法在溶胶－凝胶上的应用，包括如下几个方面：（１）改变一些醇盐的溶解度，使之溶解在醇溶剂中；（２）控制先驱体的反应活性；（３）变非醇盐先驱体为醇盐光驱体；（４）合成有机－无机复合材料；（５）通过络合剂的作用合成一些易潮解的凝胶；最后讨论了络合物凝胶的分子设计等问题。     

溶胶凝胶法制备纳米二氧化钛的工艺条件研究

以钛酸丁酯为原料，在无水条件下，采用溶胶-凝胶法制备纳米二氧化钛。通过正交实验法确定了溶胶-凝胶法制备纳米二氧化钛的最佳条件。实验结果表明：控制30min内溶解钛酸丁酯，反应完全后，静置时间为7d，500℃下煅烧时间4h，可以制备粒径小于100纳米的二氧化钛颗粒，为工业化应用提供基础数据。     

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。     

Fast Gel Permeation Chromatography Using Large Gel Particles

Abstract

In two previous papers (1,2), we reported the effect of several operational parameters on separations by gel permeation chromatography (GPC). These studies included the effects of (a) solvent flow rate, (b) sample concentration, (c) sample molecular weight, (d) particle size, and (e) operating temperature. In this present study, we used extremely large particles (200–300 μ diameter) at flow rates up to 10 ml/min. This was done to magnify solute diffusion effects in hope of gaining a better understanding of the permeation process. By using the relatively large particles, interstitial spaces between particles will be wider and the gel pores deeper than with particles normally used (less than 75 μ) in GPC.     

刺激应答性高分子凝胶

刺激应答高分子凝胶具有在温度、PH、溶剂组成改变或在外加电场、光照刺激下,体积发生剧烈变化的应答功能。可作为一种新型的智能材料。     

Gel in polyethylene

A quantitative test for the presence of gel (insoluble polymer) in polyethylene is described. A number of experiments were performed by using the test and on the polymers separated by the test. It is concluded that gel is crosslinked polyethylene in the form of discrete particles of significant size, the large ones, probably weighing up to at least 10 mg. Some crosslinks are broken by treatment with solvents above 200°C., and much of the gel is thus rendered permanently soluble. Gel is also insoluble in the reaction medium in which it is produced. Thus, even if the ethylene–polyethylene phase relationships would predict a homogeneous reaction, the reaction must be hetero-geneous if gel is present. Therefore, kinetic treatments of ethylene polymerization which do not consider phase separation when gel is found in the reaction product are oversimplified.     

Gel Filtration Chromatography

Abstract

The technique of gel filtration chromatography is described, with a guide to relevant literature on methods, theory, and applications, especially the use of GFC in analysis of molecular interactions, both macromolecular and small molecule-macromolecule aggregation.     

纳米复合凝胶聚合物电解质的研究进展

在论述了凝胶聚合物电解质改性用的无机纳米粒子的种类(包括金属氧化物、非金属氧化物以及粘土)和性质的基础上,分析了无机纳米粒子做为添加剂对凝胶聚合物电解质性能的影响。     

Active Polymer Gel Actuators

Many kinds of stimuli-responsive polymer and gels have been developed and applied to biomimetic actuators or artificial muscles. Electroactive polymers that change shape when stimulated electrically seem to be particularly promising. In all cases, however, the mechanical motion is driven by external stimuli, for example, reversing the direction of electric field. On the other hand, many living organisms can generate an autonomous motion without external driving stimuli like self-beating of heart muscles. Here we show a novel biomimetic gel actuator that can walk spontaneously with a worm-like motion without switching of external stimuli. The self-oscillating motion is produced by dissipating chemical energy of oscillating reaction. Although the gel is completely composed of synthetic polymer, it shows autonomous motion as if it were alive.     

Gel formation in ionomers

A theoretical study of the phase diagram of ionomer solutions in water is presented. These systems show two phase transitions: a demixing transition and a gelation. The demixing transition is studied using Flory's theory of polymer solutions. The gelation concentration always scales as the overlap concentration $\text{c1}$; the dependence of the phase boundaries on temperature and on the fraction f of metallic groups along the chain is studied. At high temperatures, in a good solvent regime, c_gel is proportional to $\text{f}{}^{\mathrm{<mtext>-8</mtext><mtext>5</mtext>}}$; at lower temperatures c_gel is proportional to f^?1.     

Gel Removal in Electrophoresis

Abstract

One of the most painstaking and time-consuming tasks involved in polyacrylamide disk electrophoresis is removing the gel from the glass tube. The problem becomes especially acute when high percentage (greater than 20%) acrylamide gels are used. Such gels are not only extremely stiff but also quite brittle and easily scratch or break.

We have had success with a simple but highly efficient system for gel removal (Fig. 1). It could prove quite useful for laboratories dealing with large numbers of samples; perhaps even rapid enough for clinical use. A 18-mm × 6-mm vacuum hose 6 cm long is connected to the air outlet (which delivers approximately 50 psig) with a hose clamp. The other end of the hose is connected to an air valve. A second valve allows more precise control of the air pressure. A piece of similar vacuum tubing 10 cm in length is clamped to the opposite end of the second air valve. A 1/8-in. hole is drilled about 4 cm from the exposed end of this hose. A finger adjustable hose clamp is fitted over the exposed end.     

关于冻力降

蒸发过程不仅会损失黏度,而且也会损失冻力。本文对冻力降作了初步研究,发现在大生产中冻力损失通常会损失20 Bloom-g。此外,通过将成品胶溶解后于65℃放置的试验发现,一道胶的冻力降往往要多于二道胶。     

Gel filtration of surfactants

A simulation technique was developed for analyzing the gel filtration chromatography of surfactants. Theoretical elution curves obtained by this technique were compared with the experimental curves for the following five systems: an ionic or a nonionic surfactant of a single component, an ionic surfactant in the presence of an electrolyte, a mixture of two nonionic surfactants, a mixture of two ionic surfactants, and a mixture of an ionic and a nonionic surfactant. In the first four systems, good agreement was found between the theoretical and experimental elution curves. A possible explanation for the disagreement in the last system is presented.