Acrylic copolymer intercalated in sodium montmorillonite: a modifier of reactive hot melt polyurethane adhesive

An acrylic copolymer, with PEG branches intercalated in the gallery of sodium montmorillonite (Na-MMT), was applied as a modifier of reactive hot melt polyurethane adhesive (RHA). The adhesion properties showed that the acrylic copolymer can effectively improve the initial bond strength and reduce the set time of RHA. The effects of the acrylic copolymer on the rheological and tensile properties of RHA were also examined.     

基于染料吸收的光导纤维SO2传感器

建立于气液两相平衡的气敏电极已为人们所熟知。近年来研究了气液两相平衡的光纤化学传感器。作者之一曾报道了CO_2荧光传感器。本文在文献基础上对基于染料吸收的光纤SO_2传感器进行了探讨性的研究。光纤SO_2传感器在其结构上与气敏电极相似,所不同是采用感应膜光信号变化的特征而不用指示电极进行测定。由于测定方法不同才使它具有光纤化学传感器的特殊优点。     

牛血清蛋白在NaCl水溶液中渗透压的研究

将NaCl水溶液中带电蛋白质分子间的静电排斥作用用Yukawa位能函数描述,蛋白质分子间的色散作用用Lennard-Jones位能函数描述,代替了经典DLVO理论。基于McMillan-Mayer渗透压统计理论,将Duh和Mier-Y-Teran的Yukawa状态方程与Cotterman等的Lennard-Jones微扰公式相结合,建立了一个新的状态方程,并采用该状态方程研究了含有NaCl的牛血清蛋白(简称BSA)水溶液的渗透压,依据BSA在0.15mol/LNaCl水溶液中的回归参数可预测其在1～5mol/LNaCl水溶液中的渗透压。该状态方程采用了两个回归参数(硬球直径和LJ参数),具有一定的关联和预测效果,并与己有的其它理论模型进行了比较。     

内压与非电解质溶液理论

本文用热学方法,为非电解质溶液建立了一个无热溶液理论.这个理论不包含任何可调参数,完全可由纯组分的性质来预测液体混合物的过量Gibbs自由能, 倘若以知混合物的体积,还可预测其过量焓和过量熵.而这些纯组分的性质, 都与液体的内压有关, 对37 个二元系统预测结果表明, 实验值的一致性大多优于Scatchrd-Hilderand正规溶液理论及其修正型式SHFH理论.     

内压与液体混合物的超额焓

本文在前文提出的通用液体混合模型的基础上, 对其中某些近似假设和混合规则进行了合理的修正, 从而得到了一个液体混合物的超额焓与组分内压间的关系式。对于正常液体混合物, 式中有两个可调的修正系数, 对于醇-烃混合物, 则有三个可调参数。对十六个二元液体混合物的计算结果表明, 关系式不仅能准确地描述一般液体混合物的超额焓随浓度的变化规律, 而且亦适用于具有S型H^E-x曲线的复杂液体混合物。     

TBP在水相中活度系数的探讨

本文对TBP-C6H6、TBP-CCl4、TBP-CHCl3及TBP-C6H5Cl四体系作了蒸汽压法测量.对TBP-C6H5Cl体系作了^3^2P标记法测量,其它三体系^3^2P标记法数据取自文献.分析了二种测量的结果.所得的稀释剂的活度系数应该基本一致.     

Interfacial adhesion between semi-crystalline polymers (polypropylene and nylon-6): in situ compatibilized interface and fracture mechanism

The interfacial fracture toughness between semi-crystalline polymers (polyamide/polypropylene) were studied to understand the failure mechanisms at the interface, especially when the interface was reinforced by an in situ compatibilizer. Based on the observation of the interface using scanning electron microscopy and wide angle X-ray spectroscopy, it was revealed that crystalline structure of polypropylene was not affected by the in situ compatibilizer at the interface. The reinforcing mechanism could be qualitatively identified by investigating the evolution of fracture toughness as a function of annealing time and temperature. The adhesion strength increased with the annealing time. Depending on the annealing temperature, the fracture toughness passed a peak value and then reached a plateau after some bonding time. As long as the chain length of the compatibilizer is long enough to form entanglements with the molecules at both bulk sides, the fracture at the interface is decided by the balance between adhesion strength at the interface and cohesive strength in the weak modulus side; the failure locus follows the lower one. Thus, adhesive failure occurred first when the reaction at the interface did not occur long enough to provide high adhesive strength at the interface, but the cohesive failure occurred in the crack propagation side after the adhesive strength value became higher than the cohesive strength value.     

Increase in the molecular component of the adhesive pressure in polymer composites induced by electric charge

The effect of electric charge, present at a glass fiber–polymer interface during the composite material formation, on the adhesive pressure between the components was studied. Additional electric charge was delivered to the interface by means of the deposition of charged polymer particles onto the fiber surface from a fluidized bed in an electric field. The adhesive pressure was calculated using the results of the variational mechanics analysis by Scheer and Nairn from the data obtained with a single fiber microbond test. Our experiments showed that the adhesive pressure increased by 15–20% in the case of charged polymer matrices. This can be attributed to both intensification of van der Waals forces due to extra interfacial pressure and, for polar polymers, the increase of the surface concentration of local adhesive bonds. The mechanical and kinetic models have been proposed to describe the observed behavior of the adhesive pressure; theoretical curves for the adhesive pressure as a function of the time and temperature of the contact formation, including the effect of electric factors, have been obtained. From the kinetic model, the activation energies for the process of adhesive contact formation were determined. The effect of acceleration of adhesive bonding in the presence of electric charge can be explained in terms of a decrease of the activation energy for local bond formation in an electric field.     

Applications Analytiques de la Mesure des Tensions de Vapeur par Saturation d'un Gaz Inerte Cas des Alcanes Normaux et des Polyethyleneglycols

Abstract

The vapour pressure (10^?3 to 10 mmHg) of n alkanes (hexadecan to octacosan) and a serie of polyethylene glycols (molecular weight 50 to 400) have been determined by the inert gas saturation technique. The relation between P and the number of carbon atoms or the temperature are given. The method can be used to identify fractions in liquid chromatography.     

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。