顺丁橡胶分子结构参数对其浓溶液流变性质的影响

对顺丁橡胶浓溶液作了较为深入的研究,主要讨论了分子量分布和支化因子与顺丁橡胶浓溶液流动行为的关系。用倒沉淀分级的方法进行了大量分级,得到分子量分布较窄的试样;对这些试样用GPC-自动粘度计联用的方法测定了分子量、分子量分布和支化因子,同时用同轴圆筒式粘度计及落球方法测定了这些试样的浓溶液粘度。     

用GPC测定木素分子量及分子量分布的研究概况

<正> 木素结构的探索和工业应用的研究是当代木材化学科研工作的重要课题。这些工作都和木素分子量及分子量分布密切相关。然而,在一般测定高聚物分子量及分子量分布的方法中,超离心法是曾被认为应用于木素分子量及分子量分布测定最成功的方法,但其最好的结果也还不足于推算出木素分子量分布的具体数据。用凝胶渗透色谱法(简称GPC)测定木素分子量及分子量分布是六十年代发展起     

用凝胶渗透色谱谱图计算氯化氯丁胶的粘度方程常数

众所周知,分子量对高聚物的使用性能和加工性能有重要的影响。测定高聚物的分子量是控制生产和了解产品性能的重要分析手段之一。而粘度法测定分子量,仪器简单,数据处理简便,是目前应用最广泛的测定分子量的方法之一。但是,为了从粘度数据得到分子量的确切数值,需要已知Mark-Houwink方程的K、a值,一般确定K、a值,需要将样品分级,并用绝对方法测定各个级分的分子量及测定各级分的[η]。用log[η]对     

关于测定高分子溶液渗透压的半透膜的若干问题

渗透压法是测定高聚物分子量和研究高分子溶液性质的主要方法之一。在廿年前渗透压法几乎是测定高聚物绝对分子量惟一的方法,因超离心机的设备并不是每个实验室都能建立,光散射法在1944年才由德拜(D(?)bye)应用到高分子溶液,溶液热力学性质的诸方法如沸点升高法、冻点降低法和蒸气压法等基于溶液性质的依数性测定分子量,由于高聚物的特点分子量很大,即单位重量内的分子数很少,要求实验的灵敏度和稳定度很高,通常以适用于分子量在二万以下的测定,故数均分子量主要依靠渗透压法。如所周知,使用     

人参皂苷的基质辅助激光解吸质谱研究

利用MALDI-TOFMS测定了八种人参皂苷的分子量, 并分析了西洋参总皂苷的组成。同时, 进行了灵敏度实验, 并探讨了基质及碱金属离子的影响, 证明该方法灵敏度高, 重复性好, 结果准确。是测定极性小分子分子量的有效方法。     

用MALDI-TOF-MS法快速测定天花粉蛋白分子量

采用ＭＡＬＤＩ－ＴＯＦ－ＭＳ法快速测定了天花粉蛋白的分子量,并讨论和对比了三种不同基质对其影响,认为用基质芥子酸是最佳适宜条件。实验结果表明本方法优于其它传统的测定生物大分子分子量方法。     

软电离质谱法研究锂系预聚物

高分子化合物的分子量及其分布是研究高分子材料物理性能的最基本参数之一,分子量及其分布的测定在高分子研究与发展中具有极端的重要性.分子量分布不同,聚合物的物化性能不同,所以历来受到聚合工作者的重视,传统的分析方法是利用凝胶渗透色谱法(GPC),该方法自从本世纪60年代问世以来,使得高分子化合物的分子量及分子量分布的测定变得快速和可靠.但是该方法的缺点是需要校正样品;测出的是相对分子量,而且仅适合于分子量大于2 000的样品,对于1 000左右的小分子量聚合物则无能为力.本文应用软电离质谱技术FAB-MS、FD-MS、MALDI-TOF-MS对合成的两种锂系预聚物进行了分析,并对分析结果进行了讨论.     

粘度法测定高聚物的分子量

一、引言分子量是高聚物的最基础数据,在了解聚合作用的进度和叙述聚合物成品的规范时,都须要测定分子量。高聚物的分子量很大,一般地说,在10~3—10~7的范围内。目前用以测定这些分子量的实验方法,大都是利用高分子在溶液里的性质:     

GPC-多检测联用技术测定聚己内酯分子量及其分布

介绍一种用于生物可降解高分子材料聚已内酯(PCL)及其改性高分子的分子量和分子量分布测定的GPC-示差折光(RI)-示差黏度(DV)-直角光散射(RALLS)多检测联用技术.叙述了该方法的实验原理,并对测试过程中的有关技术及实验结果进行了讨论.该方法可准确测定聚己内酯(PCL)及其改性高分子的分子量及其分布、特性黏度分布、Mark-Houwink方程系数以及高分子尺寸等重要参数.通过对窄分布PS标样验证,分子量测定结果的相对误差在1%之内.     

气相渗透法中的溶质吸附效应

在气相渗透仪上，用四个低分子量有机化合物和五个已知平均分子量的窄分布聚苯乙烯低聚体，对ＶＰＯ方法中的溶质吸附效应作了研究，提出了一种对吸附效应作改正的方法．所得结果表明，在扣除溶质吸附效应后，仪器常数Ｋ无分子量依赖性，提高了测定低分子量聚合物数均分子量的准确性．     

卤代烷烃的交叉构象的计数

1969年,Derek Bardon和Odd Hassel由于在构象分析方面取得的成就获得诺贝尔化学奖,从此,构象研究十分活跃,随后,有机分子的交叉构象计数的研究也开始了（尽管此前已经有人做出过重要的工作）,发现烷烃的交叉构象数与其一些物理性质有关,如光谱,粘度等。     

A digital simulation study of two-dimensional convection diffusion for channel electrode

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On the enthalpies and entropies of formation of solid nickel—zinc alloys

The enthalpies of formation of solid nickel—zinc alloys have been measured at 355 K using an isoperibol calorimeter and the technique of tin-solution calorimetry, and values have been obtained for the nickel-rich α-solid solutions and for the β₁, γ, γ₁ and δ intermediate phases. Exothermic values have been observed throughout and these have been compared with the results obtained in previous free energy studies and with those suggested by the empirical model of Miedema. The existing free energy data have been re-assessed at 900 K and the results combined with the present calorimetric enthalpies to derive entropies of formation. The possible contributions to the entropies of the phases are discussed and their Debye temperatures are estimated.     

Models to estimate viscosities of ternary metallic melts and their comparisons

Viscosity is an important property that influences industrial processes relevant to fluid. The transferring rate of impurities, such as S, P and N, is affected with the viscosity of metallic melts. The interfacial reactions and impurity removal depend on the viscosity of both slag and metallic melt. Viscosity of gas and liquid are all affecting the transferring process and velocity. However, the amount of viscosity data is far from satisfactory for the needs of today抯 technology, especially…     

吩噻嗪、N-甲基吩噻嗪及其自由基正离子的结构和电子光谱的理论研究

用INDO系列方法对吩噻嗪、N-甲基吩噻嗪及其自由基正离子进行了几何构型优化, 中性分子为蝶状折叠形, 自由基正离子为平面构型。以优化构型为基础,计算了上述四种分子、离子的电荷密度、自旋密度、键序和电子光谱, 对光谱进行理论指认的同时, 讨论了从中性分子到离子谱带红移的原因。所有理论计算值均与实验值一致。     

Physicochemical studies of octadecyl-trimethyl-ammonium bromide: a critical assessment of its solution behavior with reference to formation of micelle, and microemulsion with n-butanol and n-heptane

Octadecyl-trimethyl-ammonium bromide (C18TAB) is a much less studied representative in the alkyltrimethylammonium halide surfactant series. A comprehensive study of its normal and reverse micelle (microemulsion) formation has been herein conducted by the methods of conductometry, tensiometry, fluorimetry, and microcalorimetry. The energetics of its air/liquid interfacial adsorption and self-association in aqueous solution have been examined. The phase behavior of its combinations with water, n-butanol, and n-heptane in the formation of microemulsions have been investigated with identification of a variety of phases. The energetics of formation of water dispersion in oil (w/o) has been evaluated from dilution experiments conducted at different temperatures. From the results, structural parameters of the droplets have been determined at different [water]/[surfactant] mole ratios (omega) and temperatures. The w/o dispersions have evidenced both volume- and temperature-induced conductance percolation. The results have been treated in light of the Scaling equations, and the associated parameters for the process have been determined. The activation energies for the temperature-induced percolation process of the w/o dispersion have been evaluated and assessed.     

The use of the NRTLmKW model for predicting VLE data of binary systems from the excess enthalpy data

A new local composition model NRTLmKW has been used for correlation of 15 binary excess enthalpy data. The data, binary systems formed by hydrocarbons and alkanols, have been selected to give a wide representation of various kinds molecular interactions in solution. Further the model, basing on the results of the correlation, has been used for prediction of excess enthalpy and VLE (vapour-liquid equilibria) in these systems. The obtained results have been discussed from the point of view of intermolecular interactions and some recommendations have been made on the use of the NRTLmKW model for such calculation.     

Applications of Amperometric Silica Sol-Gel Modified Enzyme Biosensors

ABSTRACT

The applications of amperometric sol-gel modified enzyme biosensors in numerous analyses of clinical, industrial and environmental importance have been demonstrated. Certain biosensors have been employed as the sensor in a FIA amperometric detector. The results obtained by the biosensors generally corroborate well with the classical or official method. In many cases, the recovery results obtained by the biosensor have been satisfactory.     

Pt/HM、Pd/HM催化剂上CO氧化反应活性和动力学研究

研究了Pt/HM、Pd/HM催化剂上CO氧化反应的活性,求出了各种催化剂的CO氧化反应动力学方程。考察了不同气氛下CO氧化活性的演变规律和V⁴⁺、Co²⁺离子对Pt、Pd的助催化作用,并用催化剂集团结构适应模型对以上结果作出了解释。     

A study of the effect of network angle of fabrics on kinetics of impregnation upon molding of articles made from carbon plastics

The permittivity coefficient, volume, and porosity of an elementary cell of fabric filler have been calculated. Two types of fabric structures have been considered using the example of carbon fabric: standard, in which filament yarn is cylindrical, and spread, it which it has a rectangular shape. A reflector of a mirror space antenna has been considered characterized by the presence of doubly curved surfaces is used as the object of study. Modeling of the kinetics of impregnation of reflector for two types of fabric structures has been carried out using the RAM–RTM program. In the work, the effect of the network angle on the duration of impregnation process has also been investigated. Based on the results of calculation, reflector samples have been made and their quality has been evaluated. Theoretical and experimental results have been compared.