磁性粒子浓悬浮体系沉降稳定性的光学表征

报道一种新的磁性粒子浓悬浮体系沉降稳定性的表征方法.对均匀分散的磁性粒子浓悬浮体系,采用定时光度测量法对其沉降稳定性进行表征,可以得到一定时间内粒子沉降的定量数据.此方法可用于低体积分数磁流变液沉降稳定性的表征.同时,对比分析表明,在磁性粒子浓悬浮体系中加入纳米级TiO2粒子,能使制备的磁流变液稳定性显著增强.     

流动注射-分光光度法用于固-液吸附体系表观吸附速率常数测定

利用流动注射分析技术具有定时、定量取样、耗样量少、系统稳定性高等特点,将流动注射-光度检测法应用于固-液吸附体系的动力学研究中,结合固-液界面吸附动力学方程,测定固-液吸附体系表观吸附速率常数,作为一种新的动力学研究手段和方法,应用于物理化学的实验教学中。     

自制半透膜及渗析实验的改进

1.半透膜制作将纤维乙酸酯按10％的比例溶于丙酮,配制成制膜液,适量制膜液倒入容器(小烧杯或试管)内,然后转动容器,使膜液充分与容器壁接触。将容器倒置于一平面上,则多余的膜液流出。此时膜液在容器壁上自然流动成膜。5--10分钟后将此容器投入冷水中,(流动时间越长制出的半透膜越透明)保持着容器壁形状的膜逐渐凝固成形。从容器中将制好的膜拉出备用。     

铜(Ⅱ)在双表面活性剂液膜体系中的迁移行为

乳状液膜分离技术具有快速高效、选择性强、富集比大等优点[1-4],但该技术目前大多还处在实验阶段,要实现工业化则必须解决液膜稳定性、有毒试剂的使用及二次污染等问题.表面活性剂对于乳状液膜的形成和稳定至关重要[5-7],而在液膜体系中采用复合表面活性剂,能改善液膜性能,提高膜稳定性及传质效率[8].本文研究了铜(Ⅱ)在span80-SDS-NH3液膜体系中的迁移行为.体系中无流动载体,利用内、外相中被分离物的浓度梯度促进物质迁移.当Cu2+进入内相时,与NH3产生络合反应,使内相中游离的铜离子浓度趋于零而促使其由外相进入内相,实现Cu2+与外相溶液的分离.     

磁流变液效应对远端流场的扰动

研究了磁流变液效应对远离磁极的流道中流动的扰动问题.通过双腔型结构器件的动态力学响应以及混合流模式的流动分析,揭示了当磁流变液离开磁极后,由于剩磁的影响,磁极后方的管道中的流动将受影响,主要表现在流过管道的介质的体积比浓度将发生显著变化.     

水性聚氨酯甲阶酚醛水分散液微观形态及杂化膜的性能

以自乳化型聚氨酯和甲阶酚醛制备了聚氨酯 酚醛复合水分散液 .pH值与酚醛溶解度的关系表明甲阶酚醛的溶解是酚羟基电离的结果 .聚氨酯 甲阶酚醛水分散液粒子的形态有核壳结构、不完善的核壳结构及纯聚氨酯颗粒三种 ,后者粒径最小 .随着酚醛用量的增大 ,粒子平均粒径增大 .酚醛含量增加使体系热稳定性、机械稳定性、冻融稳定性及临界聚沉值下降 ,pH值稳定范围变窄 .分散液稳定性和电性能考察证明 ,本复合分散液的稳定性主要由分散液的电性能所决定 ,属真溶胶 ,但在一定程度上也具有大分子溶液的特性 .复合液涂膜的性能较纯聚氨酯有所改善 ,尤其在添加了硅溶胶之后     

甲基磺酸亚锡溶液中不同稳定剂的作用机制及电化学性质

研究了对苯二酚、邻苯二酚、间苯二酚和抗坏血酸4种稳定剂对甲基磺酸亚锡电镀液稳定性、电极极化及镀层表面形貌的影响.采用循环伏安法探究了镀液稳定性与稳定剂电化学性质的关系,通过交流阻抗和计时电位考察了稳定剂对镀液阴极极化性能的影响,分析了对苯二酚在电镀过程中的循环使用原理及对苯二酚的最佳使用浓度.结果表明,镀液的稳定性与稳定剂自身的还原能力及电化学活性之间存在重要联系,4种稳定剂对镀液稳定作用的大小顺序为对苯二酚邻苯二酚抗坏血酸间苯二酚,稳定效果最好的对苯二酚可以将镀液的储存时间延长一倍;苯二酚类稳定剂可以提高锡沉积的阴极极化程度,使晶粒细化,而抗坏血酸对锡沉积起到去极化作用;对苯二酚在电镀锡过程中兼具抗氧化剂、光亮剂和整平剂的作用,镀层的耐蚀性能测试结果表明,对苯二酚的最佳浓度为1.0 g/L.     

高温合金痕量分析中激光剥蚀电感耦合等离子体质谱的分馏效应机理研究

详细研究了高温合金样品剥蚀过程中激光脉冲能量及频率与高温合金痕量元素信号强度的变化及其稳定性、能量密度对信号稳定性的影响,实现了激光对样品表面的层层剥蚀,从而使高温合金中低沸点元素被稳定地蒸发,并初步建立了激光剥蚀过程中理想的样品激发动力学模型.研究表明,激光剥蚀的过程是一个在固-液-气的相变基础上进行的热蒸发过程,分馏效应是基于各元素不同的蒸发能而发生的低沸点元素的选择性蒸发;随着剥蚀的层层推进,热效应的累积导致样品表面气化层下方的固-液相变,低熔点元素出现局域富集从而使信号增强是分馏效应的另一原因.     

一种光致相变型偶氮苯基柔性光热转换器件的制备及性能

设计合成了一种具有室温光致固液转换性能的偶氮苯衍生物1-[4-(烯丙氧基)苯基]-2-(对甲苯基)二氮烯(AD-Azo)用于制备太阳热能燃料(STFs),结合其固液转换过程中的相变潜热,较大幅度提高了偶氮苯衍生物的能量存储密度.在光/热诱导下使其与普通商用布料结合,制备了环境友好、即用式柔性太阳热能燃料器件AD-Azo STF.利用织物内分子间超分子作用(氢键),增强了能量存储密度和储能寿命,使其总储能密度高达199.12 J/g,储能半衰期为50 h.该柔性AD-Azo STF器件具有良好的柔韧性、溶剂稳定性和循环使用性,在环境友好型太阳热能燃料中具有良好的应用前景.     

基于刻蚀反应的纳米结构空心化（英文）

中空纳米材料的可控合成使其在催化、能量转换与储存、生物医药等领域具有广阔的应用前景.本专论旨在揭示刻蚀反应对纳米结构空心过程的关键影响.讨论了通过增强纳米粒子表面在刻蚀液中的相对稳定性来精确操纵中空化过程的策略,主要关注3种刻蚀策略,包括硬模板法、氧化还原辅助中空法和表面钝化自模板法.最后,对基于刻蚀反应的纳米结构空心化可控合成未来的发展方向进行了展望.     

聚合物胶乳的立体稳定性

本文首先叙述了影响聚合物胶乳稳定性的各种效应,然后着重介绍了立体稳定的基本原理。     

叶绿素锌钠盐的制备及其稳定性

以鲜菠菜叶为原料,经过皂化、酸化、锌代及成盐等过程,得到叶绿素锌钠盐;测定了其紫外可见吸收光谱;利用相对光强度探讨了叶绿素锌钠盐的光稳定性和热稳定性,以及几种食品添加剂和常见金属离子对叶绿素锌钠盐稳定性的影响.结果表明,叶绿素锌钠盐的耐光性较差,在一定温度下具有较好的耐热性.几种常见食品添加剂对叶绿素锌钠盐的稳定性影响不大;银离子对叶绿素锌钠盐的稳定性影响较大.     

纳米Fe3O4磁性液体稳定性的研究

The effect of interaction（attraction effect and repulsion effect）between magnetic particles on the stability of nanometer magnetic fluids was analyzed theoretically. It was pointed that the size and concentration of magnetic particles and the coating of surfactant were important factors affecting the stability of magnetic fluids. Nanosized Fe3O4 magnetic fluids were prepared by the chemical co-precipitation method. Characterized by means of TEM,zeta potential and so on,the magnetic fluids had the mean size of 10 nm and exellent stability. The stability of magnetic fluids was researched experimentally as to the factors such as the method of adding starting materials,the speed of stirring,dispersion effect,surfactants coating occasion,coating time and adding amount,and pH. The affecting mechanism of these factors was analyzed further.     

制备方法对锶改性氧化铝的高温热稳定性的影响

γ-Al2O3是一种常用的催化剂载体,但对于许多高温反应体系,如汽车尾气催化净化,其热稳定性在很大程度上制约了汽车催化剂的活性和稳定性.     

Unexpected selective enhancement of the thermal stability of aromatic polyimide materials by cerium dioxide nanoparticles

The unusual effect of selective enhancement of the thermal stability of aromatic polyimide materials was established through the introduction of cerium dioxide nanoparticles into these polymers as nanofiller. Depending on the chemical structure of the polymers, a marked increase or a substantial decrease in the thermal stability of the nanocomposite material was registered by thermal analysis, as compared with that of unfilled polymer material. The positive effect was registered only for the composite materials based on the matrix polyimides containing the sulfur atoms located in the sulfonic groups arranged in the elementary units. The results of the thermogravimetric examination are compared with the data obtained during the mechanical tests of the same samples. The possible reasons for the alteration of the thermal stability of polymers by ceria nanoparticles are discussed. The effect above can be of substantial practical interest providing new options for the design of polyimide nanocomposite materials with enhanced thermal stability.     

The influence of alkyl chain branching on smectic C formation

Fifty-five esters were prepared to show the effect of altering the point of alkyl chain branching on smectic C thermal stability. Six types of ester system were studied. Moving the position of alkyl chain branching away from the main molecular core enhanced smectic C thermal stability; after about the third carbon this effect was minimal. Extending the alkyl chain after the point of chain branching gradually lowered the smectic C thermal stability.     

聚丙烯成核剂成核效应及热稳定性研究

为表征在聚合物材料热加工成型过程中成核剂的成核效果的热稳定性，设计了用反复升降温ＤＳＣ实验，通过观察聚合物结晶温度和结晶热焓在反复升降温过程中的变化来考察成核剂的成核效率的稳定性．研究了碳酸钙、苯甲酸钠、对苯二甲酸和脂肪二元酸：庚二酸、辛二酸、壬二酸及其与碳酸钙组成的双组分成核剂对聚丙烯结晶成核效果的热稳定性．结果表明，高熔点物质碳酸钙、对苯二甲酸、苯甲酸钠的成核效果的热稳定性高，而脂肪二元酸的成核热稳定性低．庚二酸与碳酸钙组成的双组分成核剂的成核热稳定性高，但辛二酸、壬二酸与碳酸钙组成的双组分成核剂的成核热稳定性没有得到改善．这可能是由于庚二酸与碳酸钙之间存在某种相互作用，从而使成核效果得以稳定，而辛二酸、壬二酸与碳酸钙组成的双组分成核剂中，两个组分基本独立存在．     

聚合物对硫化铅钠米微粒的稳定作用

以含铅聚合物微凝胶与Ｈ２Ｓ气体反应制得ＰｂＳ纳米微粒／聚合物复合体系，利用小角Ｘ光散射方法对复合在聚合物中的ＰｂＳ纳米微粒的粒度及分布进行了表征，研究了不同反应条件对其粒度及复合体系稳定性的影响。     

Thermo-oxidative stability of polypropylene/layered silicate nanocomposites

Several series of experiments were carried out to check the effect of components on the stability of PP/layered silicate nanocomposites. The amount of organophilic montmorillonite (OMMT) changed between 0 and 6, while that of maleated polypropylene (MAPP) between 0 and 50 vol%. The composites were prepared in an internal mixer at 190 °C. Mixing speed and time were changed to study the effect of processing conditions on stability. The structure of the samples was characterised by various methods, while stability by the induction time of oxidation (OIT), the onset temperature of degradation (OOT) and by colour. Contrary to numerous claims published in the literature, which indicate the positive effect of layered silicates on the stability of polymer nanocomposites, our results clearly proved that both OMMT and MAPP accelerate degradation during processing and deteriorate the properties of PP composites. Residual stability decreases drastically with increasing amounts of both components, chain scission leads to the decrease of viscosity and to inferior strength and deformability. In spite of expectations, the effect of the components is independent of each other. Discoloration is caused mainly by the inherent colour of the filler and it decreases with increasing exfoliation. The most probable reason for decreased stability is the reaction of the components with the stabilisers, but this explanation needs further verification. Processing conditions influence degradation considerably, increasing shear rate and longer residence times lead to more pronounced degradation. The basic stabilization of commercial grade polypropylenes is insufficient to protect the polymer against degradation and without additional stabilization processing under normal conditions results in products with inferior quality.     

Au(111)/咪唑基离子液体界面结构研究：阳离子侧链长度的影响

本文结合电化学方法与原子力显微镜力曲线技术,研究了两种烷基侧链长度不同的离子液体BMITFSA和OMITFSA在Au(111)电极表面附近的层状结构的数目和耐受力对电位的依赖性,探究了烷基侧链长度变化对界面层状结构的影响. 研究表明,不同烷基侧链长度的离子液体体系力-电位曲线形状基本相似. 在零电荷电位（the potential of zero charge,PZC）附近时,力值最小,因为此时电极表面荷电量较小,层状结构不稳定;电位偏离PZC的过程中,第一层层状结构力值呈现先增大后减小的趋势. 受到烷基侧链所处的不同位置影响,在PZC电位以负,短侧链离子液体的层状结构稳定性较好,而PZC电位以正,长侧链离子液体的稳定性较好.