丁二酸二异辛酯磺酸钠在长链醇/N,N-二甲基甲酰胺体系中临界胶束浓度和热力学函数的微量量热法研究

用微量量热法研究了丁二酸二异辛酯磺酸钠(AOT)在N,N-二甲基甲酰胺(DMF)/长链醇(正戊醇、正己醇、正庚醇、正辛醇)体系中的临界胶束浓度(CMC)和热力学函数( , 和 ). 并分析讨论了醇的浓度、醇中的碳原子数及温度与CMC及热力学参数之间的关系. 结果表明, 在AOT/长链醇/DMF体系中, 当醇中的碳原子数相同且醇的浓度相同时, CMC, , 随温度的升高而增大, 而 随温度的升高而降低|当温度相同且醇中的碳原子数相同时, CMC, , 和 随醇浓度的增加都降低|而当温度相同且醇的浓度相同时, CMC, , 和 随醇中碳原子数的增加都降低.     

乙醇在正己烷中的解缔与超额焓

测定了不同温度和浓度下乙醇与正己烷液体混合物的热压力系数及内压,并用修正的van der Waals模型关联了这些实验数据,从模型参数B/A2得到了一个乙醇自缔合随组成而遭破坏程度的公式.根据这个公式设想了一个醇与烃的混合模型,建立了混合物的超额焓方程,它能够满意地描述上述混合物的超额焓随组成的变化规律,并显示物理和化学作用对HE的贡献     

褐煤模型化合物与异丙醇进行醇解的反应性研究

采用密度泛函理论对褐煤模型化合物与异丙醇醇解的反应特性进行了研究。估算了醇解反应的热力学参数。提出一种将希什菲尔德电荷分布和福井函数相结合的改良方法,用以确定反应物的初始构型。将线性协同转化方法和二次同步转变法相结合用于搜索过渡态,并同时对反应物和产物的构型进行优化。经过计算发现,反应焓随温度升高而降低;反应过程中出现亲核基团;异丙醇是常用醇类中最活泼的醇解剂。因此可认为褐煤醇解反应是放热反应,反应机理为亲核加成机理。     

褐煤模型化合物与异丙醇进行醇解的反应性研究（英文）

采用密度泛函理论对褐煤模型化合物与异丙醇醇解的反应特性进行了研究。估算了醇解反应的热力学参数。提出一种将希什菲尔德电荷分布和福井函数相结合的改良方法,用以确定反应物的初始构型。将线性协同转化方法和二次同步转变法相结合用于搜索过渡态,并同时对反应物和产物的构型进行优化。经过计算发现,反应焓随温度升高而降低;反应过程中出现亲核基团;异丙醇是常用醇类中最活泼的醇解剂。因此可认为褐煤醇解反应是放热反应,反应机理为亲核加成机理。     

气液色谱法测量醇类在惰性溶剂中的无限稀热力学函数

用气液色谱法测量了在不同温度下C_1～C_4醇类的各种异构物在C_(16)～C_(23)正构烷烃、角鲨烷,和角鲨烯中的无限稀活度系数γ_i,偏摩尔过量焓、偏摩尔过量熵。在各种溶剂中γ_i、均大于1,在同一溶剂中γ_i依下列次序减小: 甲醇>乙醇>正丙醇>正丁醇; 正丙醇>异丙醇; 正丙醇>异丁醇>仲丁醇>叔丁醇同一种醇在角鲨烯中的γ_i较在角鲨烷中为低。异构醇类的低于正构醇类。所测的有随的增加而增加的趋势。     

DMFC用质子型离子液体复合隔膜的制备及性能表征

由酸碱中和法制得质子型离子液体α-甲基吡啶三氟乙酸盐,再经相转化将质子型离子液体与PVDF-HFP复合成(PIL)/PVDF-HFP膜.交流阻抗测试表明,复合膜电导率随温度增加而递增,室温电导率:8×10-3S/cm,30℃电导率:1×10-2S/cm,80℃电导率:3×10-2S/cm.用计时电流法研究复合前后膜的甲醇渗透性能,结果显示,该离子液体复合前、后膜的阻醇性能无明显变化,但复合膜阻醇性能略优.     

芳香氨基酮选择性还原反应的研究

非均相催化剂(钯碳催化剂)一般会将芳香酮彻底还原至亚甲基产物,而不易得到苄醇类的中间还原产物.本文报道一系列氨基酮用钯碳催化剂催化氢化的结果,随酮底物含有不同种类的氨基而得到不同的氢化产物(亚甲基产物或二级醇产物),部分则不发生还原反应;分析讨论了底物所含氨基对产物的影响及其机理.结果表明,这是一个制备胺基芳香仲醇的有效方法.     

液浸冷却系统中丙三醇液体的耐受性分析

设计了高温、紫外及温度紫外耦合实验考察丙三醇的耐候性.利用紫外可见光谱仪、红外光谱仪检测实验前后丙i醇性质的变化,并测试了液浸硅电池的电性能和表面形貌的变化.结果表明,实验后丙三醇的光谱透过率在小于600nm的低波段有所降低,红外光谱显示其发生了氧化反应生成微最的羰基.用丙三醇液浸硅电池的电性能没有衰降,但是电池表面出现了微量颗粒状物质.用理论分析了液体性质变化的原因,并由此建议醇类液体不适于在液浸光伏系统中作为冷却液体.     

液体分子自扩散系数的预测

基于液体层膜结构模型提出预测液体分子自扩散系数的方程,对24种液体在较宽温度范围内作了检验,平均偏差为3.8%。同时分析了层膜结构模型中位形参数ξ随温度和物质不同而变化的规律,这对了解液体的微观结构、扩散过程的机理和阐明层膜结构模型的合理性具有重要意义。     

醇类的缔合作用与热压力系数

测定了甲醇、正丙醇、正丁醇和正癸醇在25-85℃温度范围的热压力系数, 并为正构醇液体建立了一个热压力系数与密度间的通式。这个通式可用来预测正构醇在各种温度下的内压值。用同形物近似法, 本文还获得了正构醇缔合作用的若干重要信息和估计其缔合度的近似方法。     

液体的热压力系数及内压

本文从排斥体积要随密度改变的概念出发,修正了原始的Van der Waals理论,并建立了一个计算液体热压力系数的公式 (P/I)_v=R_(ρm)/(1-A_(ρm) B_(ρ~2m))式中ρm=1/V_m是液体的摩尔密度,A和B都是与分子大小有关的两个特性常数。因此,利用Lennard-Jones位能函数中的参数σ_(LJ)便能预测液体在不同温度下的热压力系数及内压值。     

液体的饱和蒸气压与内压

本文用统计热力学的方法, 建立了液体饱和蒸气压, 与内压间的关系式。对C6H6、CCl4、cy-C6H12、C(CH3)4、n-C6H14和(CH3)2CO等六种液体的检验结果表明, 上述关系式能适用于广阔的温度范围。     

聚合物的热压力系数及内压

本文将我们在前文中提出的修正van der Waals模型, 推广到了液态聚合物中, 从而建立了一个能在宽阔温度范围内准确计算聚合物热压力系数的关系式。式中ν和M分别为聚合物的比体积和链节的摩尔质量, A为聚合物的特性常数。对于本文考察的五种聚合物, 发现它们的链节大小均为聚合物的三个结构单元。     

High pressure sorption isotherms via differential pressure measurements

A differential pressure adsorption unit (DPAU) has been constructed which is capable of accurately measuring isotherm data up to 2000 psia with as little as 100 mg of sample. This non-traditional adsorption/desorption method has been benchmarked by comparing hydrogen and methane isotherms measured with standard volumetric and gravimetric instruments on a NaA (4A) zeolite and an activated carbon at near ambient temperatures. The results from stability tests and well as the details of the mathematical analysis for this differential pressure method are also provided.     

溶液的热压力系数及内压

在作者的前一篇论文中,已由修正的Van der Waals模型建立了一个液体热压力系数与密度的关系式并据此得到了一个计算液体内压的公式 2)式中pm是液体摩尔体积V_m的倒数,称为摩尔密度,T是热力学温度,R是通用气体常数,A     

Internal pressure and solubility parameter as a function of pressure

The main goal of this work was to measure the solubility parameter of a complex mixture, such as a crude oil, especially as a function of pressure. Thus, its definition is explained, as well as the main approximations generally used in literature. Then, the internal pressure is investigated, since it is presented as an alternative of the solubility parameter. In this work, the assumption that internal pressure is a measure of the physical solubility parameter was made, i.e. representing the dispersion and polar forces. As for the pressure influence, it was seen that internal pressure reaches a maximum contrary to solubility parameter.An indirect method was chosen to estimate internal pressure, using thermal expansivities (determined by microcalorimetry) and isothermal compressibilities (determined by density measurements). The uncertainty is within 2% for the expansivity and 0.1% for the density. Five pure compounds (four hydrocarbons and 1 alcohol) were investigated at 303.15 K and up to 30 MPa, as well as a dead crude oil. The “physical” solubility parameter is slightly increasing with pressure (up to 0.8 MPa^1/2 for cyclohexane) and, at 0.1 MPa, the difference with literature data is less than 1 MPa^1/2 for hydrocarbons. On the contrary, the difference reaches 9 MPa^1/2 for ethanol as expected, due to the presence of hydrogen bonding. A dead crude oil was also studied and its solubility parameter is within the expected range.Two cubic equations of states (Peng–Robinson and Soave–Redlich–Kwong) were able to approximate the “physical” solubility parameter of n-heptane (within 0.2 MPa^1/2), providing that the volumes were measured and used as input. The Peng–Robinson equation gave somewhat better results.     

Determination of the pressure coefficient and pressure effects in capillary flow

General expressions for determining the pressure coefficient and axial distribution of the viscosity and pressure in capillary flow are derived for Newtonian and shear-thinning fluids. The pressure-dependent viscosity model is obtained from the WLF equation as derived from Doolittle's free volume theory. The model has also been derived from Eyring's hole theory for viscosity. Poiseuille's equation is modified to correct for the pressure effect on viscosity. A Newtonian, low-molecular-weight polystyrene and a shear-thinning, high-molecular-weight polystyrene were tested in an Instron capillary rheometer. The axial velocity distribution was found to be negligibly affected by pressure whereas the viscosity was shown to increase markedly with a decrease in volume. The resulting pressure effects on the viscosity of both samples were analyzed by using the derived expressions.     

Atmospheric pressure photoionization-mass spectrometry and atmospheric pressure chemical ionization-mass spectrometry of neurotransmitters

A group of five neurotransmitters with different properties was analyzed using atmospheric pressure photoionization (APPI) and atmospheric pressure chemical ionization-mass spectrometry (APCI-MS). The sensitivity of the techniques for the analytes was tested in six solvents and in positive and negative ion modes. APPI was found to be superior in sensitivity for all the compounds in both positive and negative ion modes. In positive ion mode, water/methanol/formic acid was found to be the best solvent, whereas in negative ion mode, water/methanol/ammonium hydroxide performed best. Detection limits using APPI were between 2.5-250 fmol, depending on the compound. The sensitivity was best for the neurosteroids dehydroepiandrosterone and beta-estradiol, and acetylcholine (LOD 2.5-10 fmol).     

A high pressure thermobalance

A high pressure thermobalance was assembled by placing a DuPont Model 950 balance into a stainless steel enclosure. The thermobalance is capable of operation to a maximum pressure (of N₂) to 500 atm and to a maximum temperature of 500°C. Operation of the instrument is illustrated by the thermogravimetric curves of BaBr₂·2H₂O, CuSO₄·5H₂0 and NaHCO₃ at various pres