二甲基亚砜水溶液表面张力及粘度与氢键的拉曼光谱研究

利用ZL-10型全自动界面张力仪(柏金环法)和NDJ-5S型数显粘度计测量体积分数为5%～100%的二甲基亚砜(DMSO)水溶液及超纯水,得到表面张力和粘度的变化规律。用拉曼光谱仪测量不同浓度DMSO水溶液的拉曼光谱,得到体系中含氢键作用的拉曼频移变化规律。实验结果表明,DMSO水溶液的表面张力随浓度的变化受DMSO水溶液中氢键作用的影响,且与氢键强度成反相关。DMSO与水的氢键作用对粘度的影响较表面张力更为复杂,粘度随浓度的变化呈二次函数的反常现象,影响因素包含氢键强度,氢键网络结构和空间方向性多个方面。该研究探索一种利用拉曼光谱研究水溶液微观结构与宏观物理性质关系的实验方法。     

用力敏传感器测量乙醇水溶液的表面张力系数与浓度的关系

用硅压阻式力敏传感器测量了纯水、乙醇的表面张力系数，并测量了不同浓度的乙醇水溶液的表面张力系数，得到了乙醇水溶液的表面张力系数随浓度的变化曲线．     

基于氢键作用的几种二元水溶液的表面张力特性及拉曼光谱研究

氢键效应作为溶液中典型的微观特性直接影响溶液微观结构,并对物理和化学性质产生重要影响。对氢键作用的研究是水科学研究的重要突破口,也使得通过氢键研究水溶液性质成为一种极具优势的研究方法。通过测量不同浓度下的表面张力以及各体系拉曼光谱,研究二甲基亚砜/水、乙腈/水、丙酮/水三种具有典型氢键作用的二元溶液体系。研究了表面张力的变化规律和各体系中的氢键作用,讨论了溶液体系的微观结构变化,解释了氢键作用对表面张力的影响机制。     

SDBS对氧化铜纳米颗粒悬浮液粘度的影响

由氧化铜纳米颗粒、分散剂和水组成的悬浮液粘度是研究其流动与换热的重要基础数据。本文通过实验得出分散剂是影响纳米悬浮液粘度的决定性因素这一结论。研究表明,本文采用的纯分散剂溶液即十二烷基苯磺酸钠(SDBS)水溶液的粘度对温度变化很敏感,氧化铜纳米颗粒质量分数的增加对粘度的影响并不明显,而分散剂浓度对粘度的影响远远超过纳米颗粒质量分数对粘度的影响。     

基于溶液温度差谱分析的ATR-FTIR原位测量方法

作为一种原位、快速、无损坏的中红外光谱分析技术,ATR-FTIR已在很多工程领域得到越来越多的应用,尤其是针对结晶过程溶液浓度的原位实时测量。水是一种常用的结晶溶剂,在中红外波段具有强吸收峰,并且在不同温度下具有光谱吸收差异性,因而不能忽略溶剂水和温度对溶液浓度的中红外光谱测量带来的影响。以朗伯-比尔定律为基础,提出采用溶液光谱减去相应温度下的溶剂光谱的方法,从而能准确地测量溶液浓度。以L-谷氨酸溶液结晶过程为例,对L-谷氨酸水溶液的原始光谱数据、溶液光谱扣除常温(25℃)溶剂水的光谱数据以及溶液光谱对应温度扣除溶剂水的光谱数据分别进行建模。结果表明,提出的对应温度差谱法能有效消除溶剂水峰对溶质光谱测量的干扰,明显地降低了溶液浓度光谱标定模型的预测误差。该方法对提高原位ATR-FTIR光谱检测精度的实际应用具有一定的参考价值。     

Preparation and Unimolecular-Micellization Behavior of Homopolymer of Surface-Active Monomer AMC14AB

采用水溶液均聚合方法,制备了阳离子型表面活性单体(2-丙烯酰胺基)乙基十四烷基二甲基溴化铵(AMC14AB)的均聚物,使用荧光探针法、表面张力测定及电导测定法,重点考察了均聚物P(AMC14AB)在水溶液中的胶束化行为与表面吸附现象. 在水溶液中,均聚物P(AMC14AB)呈现单分子链胶束的聚集形态,具有零临界胶束浓度,从开始加入P(AMC14AB)起,水溶液中随即产生单分子链胶束,不存在Krafft温度. P(AMC14AB)在溶液表面也发生表面吸附,使水的表面张力下降,即P(AMC14AB)也具有表面活性;随着浓度增大,表面吸附量增大,水的表面张力持续下降;当表面吸附达饱和时,表面张力～浓度曲线上出现突变点,该点定义为饱和的表面吸附浓度,而不应该再称为临界胶束浓度. P(AMC14AB)单分子链胶束溶液对疏水有机物(甲苯)的增溶情况,明显不同于普通小分子表面活性剂十六烷基溴化铵(CTAB)的多分子胶束溶液,甲苯增溶量～P(AMC14AB)浓度的关系曲线上无突变点,而且对甲苯的增溶能力高于CTAB的多分子胶束溶液.     

气泡对液体粘度测量的影响

讨论了用奥氏粘度计测量液体粘度过程中,气泡对测量结果的影响,指出在用此法测量液体的粘度时,应注意选择粘度计,注入适量的液体,并排除气泡才能使测量结果准确无误。     

界面活性剂的混合添加对溴化锂溶液表面张力及吸收水蒸气的影响

本文从将两种有效添加剂混合添加的角度,来研究其对溴化锂水溶液吸收水蒸气的影响.采用静态池吸收实验测试溶液吸收水蒸气的效果.通过对正辛醇、仲辛醇、异辛醇、正己醇四种物质采用单种添加和两种混合添加的测试实验表明,混合添加后的效果与其中较好的添加剂单独添加的效果接近.采用吊板法测量溶液的表面张力.通过对添加以上混合添加剂后的溴化锂水溶液的表面张力的测试表明,混合添加后溶液的表面张力与其中较大程度降低溶液表面张力的添加剂单独添加后的表面张力接近.     

激光处理水溶液对ICP光源辐射的增强作用

为了增强电感耦合等离子体原子发射光谱强度,改善对痕量重金属元素的检测水平,本文采用波长为976 nm的近红外激光辐照水溶液,研究了溶液表面张力和粘度的变化情况,并且观测了处理后的水溶液对ICP光源的光谱强度和信背比的影响。实验结果表明：当激光辐照时间为60 min,功率密度为0.3296W·cm-2时,溶液的表面张力比未处理时的减小了36.73%,粘度减小了9.73%。将优化条件下激光辐照处理的水溶液引入到ICP光源中,通过测量发射光谱强度可知,样品元素Cd,Cr,Cu,Hg和Pb的谱线强度要比溶液未处理时的分别提高了73.52%,22.97%,33.86%,24.44% 和 65.59 %,光谱信背比分别增大了76.03%,21.74%,32.17%,22.68% 和65.32%。可见,ICP光源的光谱强度和信背比得到了明显改善,为降低元素分析检出限奠定了基础。另外,经激光处理后的水溶液在30 min静置时间内其表面张力和粘度基本保持不变,物理性质稳定。这种简便易行的激光处理水溶液方法有助于提高ICP光谱法的检测能力。     

基于表面光散射法的聚乙二醇水溶液表面张力实验研究

基于表面波散射原理,本文研制了表面光散射法表面张力实验系统。利用标准参考物质纯水和乙醇对实验系统的可靠性进行了检验,并标定了散射角度。结果表明:新系统测量的两种物质的表面张力实验结果与标准数据的偏差为0.1mN·m~(-1),散射角度约为0.2°。利用新的表面光散射法表面张力实验系统,对质量分数为4%~16%的PEG1000、PEG2000、PEG4000、PEG6000、PEG8000水溶液的表面张力进行了实验研究,结果表明:PEG水溶液的表面张力随着PEG质量分数的增大有减小趋势,且PEG水溶液的表面张力与PEG本身的聚合度无关;PEG4000和PEG6000水溶液具有较大的表面张力,可以作为潜在的诱导蛋白质结晶的沉淀剂。     

Effects of Polymer Bridging and Electrostatics on the Rheological Behavior of Aqueous Colloidal Dispersions†

Effects of a low molecular weight physically adsorbed polyethylene oxide (PEO) and the range of the electrostatic repulsion on the rheological behavior of silica dispersions (as a model system) has been investigated. Particular attention is given to the evolution of the rheological behavior with increasing the polymer concentration in the system and also effectiveness of the polymer as a dispersant under extreme conditions (high ionic strength). Results indicate that at small separation distances and low polymer coverage, the polymer chains are long enough to adsorb on the surface of two particles simultaneously causing bridging flocculation in the system and hence increasing the viscosity and linear viscoelastic functions of the dispersion. A significant increase was observed in the viscosity of the dispersion at salt concentrations high enough to eliminate electrostatics between the particles. Under these conditions,the viscosity of the system increased significantly when PEO was added to the dispersion showing that at high electrolyte concentrations, a neutral polymer such as PEO is not able to stabilize the system.     

Solution Behavior of Hydrophobic Cationic Hydroxyethyl Cellulose

The hydrophobic cationic hydroxyethyl cellulose (HEC-g-DA) was prepared by grafting HEC with various alkyl ammonium chlorides (DA) in order to improve the thickening properties of cationic hydroxyethyl cellulose. The solution behavior of HEC-g-DA was studied, and showed that the apparent viscosity of HEC-g-DA increased with polymer concentration, and there existed a critical association concentration (Cp*). The alkyl chain length of DA had a great influence on Cp*, which decreased with increasing alkyl chain length; however, too long an alkyl chain of DA reduced the water solubility of the polymer, resulting in a slight increase of Cp*. The effect of temperature and electrolyte concentration on the thickening properties of HEC-g-DA was investigated; the value of viscous flow activation energy (E_a) was minimum for the sample of HEC-g-DA16 (glycidyl-N-hexadecyl–N,N-dimethyl-ammonium chloride), indicating the weakest sensitivity of the viscosity to temperature. In the whole range of shear rate investigated, the solutions of HEC-g-DA displayed the shear thinning behavior of a pseudoplastic fluid. The values of viscous index (n) from the Ostwald model simulation decreased with polymer concentration, indicating an improvement of the shear thinning property of the solution, whereas the increase of the consistency coefficient (k) indicated the enhancement of the thickening behavior of the polymer. With increasing polymer concentration, the molecular association of HEC-g-DA16 became strong, and high-shear stress was required to remove the association, while the difference between G′ and G″ became small, indicating that the elasticity of the system was enhanced at high polymer concentration. The amphiphilic structure of the HEC-g-DA16 molecules contributed to the low surface tension of the polymer.     

Determination of the adsorbed layer thickness of polystyrene on glass surface by viscosity measurements to the extremely dilute concentration region

A newly developed theory regarding solute adsorption effect in viscometry of a polymer solution is reviewed and extended for determining the adsorbed layer thickness of polystyrene on a glass surface in viscosity measurements. This theory can adequately describe the concentration dependence of the viscosity of a polymer solution measured by glass capillary viscometer to the extremely dilute concentration region. Using this theory, both the free polymer chains in solution and the adsorbed polymer chain on the viscometer inner wall surface can be characterized. Examples are given for the characterization of six polystyrene samples with different molar masses by measuring their solution viscosity in benzene.     

Heats of solution and dilution for polyethylene oxide in several solvents

The Tian-Calvet microcalorimeter, as modified by Maron and Filisko, has been used to measure the heats of solution and dilution of a sample of polyethylene oxide (PEO) of M₂ = ca. 6000 in chloroform, methylene chloride, and water. By applying the Maron theory to these measurements, it was found from the organic solvent data that the heat of fusion of the PEO sample is 57.1 cal/g polymer, independent of the solution concentration or the solvent used. However, the solution behavior in water was different because PEO in organic solvents exists as a random coil, whereas in water its conformation is helical. By combining the water and organic solvent data, it can be shown that conversion of the random coils to the helix involves the evolution of 39.3 cal of heat per gram of polymer. This heat evolution accounts, in all probability, for the solubility of PEO in water.     

Newtonian viscosity behavior of dilute to moderately concentrated solutions of cellulose acetate butyrate

The Newtonian viscosity behavior of dilute to moderately concentrated solutions of cellulose acetate butyrate in dioxane was investigated at different temperatures. The viscosity data were analyzed in terms of Martin's and Fedor's relationships and also generalized in terms of reduced variables. The rheological behavior of cellulose acetate butyrate solutions in the whole range of concentrations is determined by the parameter (K_MC [n]). The temperature dependence of viscosities was expressed by the Arrhenius-Frenkel-Eyring equation and the activation energy of viscous flow of polymer solutions (ΔGv) was calculated. ΔGv increases with concentration of polymer solution and is independent of temperature. The preexponential factor, A, related to activation entropy, decreases with concentration of polymer solution. The thermodynamic parameter of viscous flow for cellulose acetate butyrate (CAB)-dioxane solutions is indicative of moderately stiff structure for CAB in solutions.     

微流控法二乙烯基苯乳液粒子成型机理研究

采用相界面跟踪(V()F)数值模拟方法,研究了轴流型微流控芯片中流速比、界面张力、粘度等对乳液粒子粒径的影响。模拟结果表明:乳液粒子粒径与流速比的对数存在线性关系,在一定范围内,当流速比增大时,粒径变小;当界面张力小于0.025 N/m时,乳液粒径随界面张力增大而增加,当界面张力超过0.03N/m时,乳液粒径变化趋于平缓;分散相粘度对乳液粒径的影响甚微。以聚乙烯醇(PVA)水溶液为连续相,二乙烯基苯(DVB)溶液为分散相,采用自制的聚二甲基硅氧烷(PDMS)轴流型微流控芯进行了DVB乳液粒子成型实验研究,获得了0.5~3.0 mm的DVB乳液粒子。     

低功率有机ICP中乙醇增敏效应的研究

研究了低功率有机ICP中乙醇对试液物性（密度、粘度、表面张力）及等离子体激发参数（气体温度、激发温度、电子密度和电离温度）的影响。测定了多种元素在不同浓度乙醇水溶液中的检出限。结果表明，乙醇的引入提高了分析物进入等离子体速率，并对具有低激发电位和电离电位的稀土元素有一定的增敏效应，而对具有较高电离电位和激发电位的Cd,Zn,B有抑制作用，并减弱了等离子偏离LTE状态。     

Conductivity and dielectric relaxation of Li salt in poly(ethylene oxide) and epoxidized natural rubber polymer electrolytes

Two types of polymer electrolytes were studied: poly(ethylene oxide) (PEO) and epoxidized natural rubber (ENR) both filled with lithium perchlorate. Universal dielectric behavior and impedance relaxation were investigated at room temperature over a wide range of salt concentration. Complex impedance plots exhibit one semicircle in some cases (PEO polymer electrolytes) with an extended spike at low frequencies. This implies a double layer capacity strongly influences conductivity at low frequencies. In the ENR–salt system, semicircles can be obtained only at very high concentrations. This points towards stable resistor dominated networks only develop at very high salt concentrations for this system. Centers of the semicircles lie below real axis indicating non-Debye dielectric relaxation. The relaxation peak broadens and shifts to higher frequencies with increasing salt content. It indicates that the relaxation time of polarization relaxations decreases with ascending salt content. Relaxations occur at extremely low salt concentrations in PEO and only at very high salt concentrations in ENR. Hence, conductivity of ENR–salt is one to two orders of magnitude lower as for PEO–salt.     

Effect of Added Monosodium Glutamate on Characteristics of Polyamide Dope Solutions

Formic acid (FA) solutions prepared with various concentrations of polyamide 66 (PA 66) and monosodium glutamate (MSG) were evaluated in terms of properties, such as density, viscosity, and cloud point. The influence on density was insignificant, whereas the viscosity was strongly affected by the amount of PA 66 and MSG additive. The solutions were further evaluated by casting them in a flat film form and determining the demixing time in a humid atmosphere. The considered cases at lower polymer concentrations at various MSG amounts, indicated that the demixing time increased with increase in polymer concentration. The time for demixing, however, decreased for a given higher amount of polymer when the amount of additive was increased in the dope solution. Membranes were prepared at various coagulant bath temperatures. The tensile strength and degree of adsorption (DOA) of these membranes were found. The tensile strength was higher when the membranes were prepared at higher temperature. The DOA, on the other hand, was higher for the membranes formed at lower temperature.