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41.
Palm-oil-in-water emulsions were prepared with mixtures of Tween 40 and Span 40 in various proportions. Stability and droplet-size
distribution of the emulsions were monitored. Interfacial tensions of the palm oil/water interface were also determined in
the presence of these emulsifier mixtures. Emulsifying efficiency of the emulsifier mixtures was assessed. No synergistic
effect of Tween 40 (sorbitan monopalmitate with 18–22 moles of ethylene oxide) and Span 40 (sorbitan monopalmitate) was found
on interfacial tension. Tween 40 alone (hydrophilic-lipophilic balance value 15.6) at 1.0% w/w gave palm oil emulsions that
were stable for more than 30 d at 60°C. Emulsifier mixtures of Tween 40 and Span 40 with hydrophilic-lipophilic balance values
in the range of 8.0–8.6 produced stable emulsions only at much higher emulsifier-mixture concentrations. The inherent nature
of the oil and the accompanying natural surface-active materials present in the oil can influence the prevailing conditions
at the oil/water interface and alter composition of the interfacial film and hence its stability. 相似文献
42.
Paola Scarfato Elvira Avallone Pio Iannelli Vincenzo De Feo Domenico Acierno 《应用聚合物科学杂志》2007,105(6):3568-3577
In this paper we report on the preparation and characterization of polyurea‐based microencapsulated systems, containing essential oils as core materials, for potential applications in controlled‐release formulations of agrochemicals. Microcapsules were synthesized by interfacial polymerization in o/w emulsion between polyfunctional isocyanates and diamines, to investigate the effect of the monomer kind on the morphology and properties of the produced samples. The synthetic conditions that gave the best results were used to microencapsulate four essential oils, able to interfere with the seed germination and radicle elongation of some test plants. The produced samples were characterized, with the aim to analyze their morphology and to verify the effectiveness of essential oil microencapsulation. Moreover, preliminary bioassay based on seed germination and subsequent radical growth were carried out to study the effects of the microencapsulated essential oils. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
43.
压痕法确定纤维复合材料界面影响区蠕变特性的数值模拟法 总被引:1,自引:1,他引:1
研究由平头压痕蠕变试验来确定纤维复合材料界面影响区蠕变性能参数的可行性。利用有限元蠕变分析确定在定压痕应力下的压痕蠕变率,重点放在稳定压痕蠕变率和复合材料材料界面影响区的蠕变性能参数的关系上。计算结果表明,界面影响区的剪应力沿纤维轴向在蠕变的主要过程中均匀分布,并且保持不变;详细地研究了压头大小对压痕蠕变响应的影响:提出两种方法由压痕蠕变试验来确定界面影响区蠕变性能参数,并给出了算例。这些结果也有利于准确认识平头压痕蠕变试验从而拓宽其应用范围。 相似文献
44.
以分子热力学为基础 ,对气体吸收过程进行了理论分析 ,导出了传质通量的数学表达式。根据该文分析 ,气液界面传质的源动力来自界面处气液两相的不平衡 ,即只要有传质发生 ,液相界面处的浓度就不会达到与气相呈平衡的浓度。对于气相阻力可以忽略的吸收过程 ,两相传质速率的大小主要取决于液相的溶质界面浓度和液膜厚度 ,影响溶质界面浓度和液膜厚度的主要因素是近界面液相侧的流场分布。利用近界面浓度与液膜厚度的激光测定结果 ,计算了甲醇、乙醇及正丙醇吸收CO2 气泡的传质通量 ,计算结果与实验值吻合良好 相似文献
45.
聚合物—铝酸—钙界面组成与结构的XPS研究 总被引:3,自引:0,他引:3
从复合材料界面的角度,采用XPS综合方法研究了水泥基聚合物复合材料的高强特别是高抗弯强度的微观机理。结果表明,在材料界面上存在明显的电子结合能化学位移效应,并被证实为聚合物与无机水泥的化学键合所致。界面层的深度分析发现,掺加聚合物的材料界面具有良好的化学和物理结构。作者认为这种材料的高强机理主要是由于两种基质界面间的有效化学键合作用,形成了良好的界面结构,因此,可认为这种作用大于有的学者所解释的聚合物的单一物理作用。 相似文献
46.
Toshio Kimura Yoshikatu Okada Takashi Yamaguchi Yuzo Shimada Kazuaki Utsumi 《The Journal of Adhesion》1994,47(1):179-190
Bondability and interfacial reaction between dielectric and insulator layers have been examined to obtain a basic understanding of bonding mechanisms. Lead-containing complex perovskite was used as a dielectric material. Two kinds of glass-ceramics were used as insulator material; lead borosilicate glass containing Al2O3 (insulator A) and the same containing Al2O3 and MgO (insulator B). Dielectric and insulator layers did not bond when insulator A was used. When insulator B was used, however, strong bonding was achieved between the two layers by firing the powder compacts at temperatures between 800° and 1000°C. Addition of MgO to lead borosilicate glass increased the thermal expansion coefficient to that of the dielectric and enhanced the formation of reaction layers, resulting in good bonding. Two reaction layers were identified. The main reaction products were enstatite and bredigite for one layer contacting the dielectric, and enstatite and a compound with the same diffraction pattern as that of faujasite for the other layers contacting insulator B. 相似文献
47.
The preparation of dibasic acid-containing soy phospholipid was made by transesterification reaction with alkyl ester of diabasic acid with both lipase and alkoxide as a catalyst. The extent of incorporation of a dibasic acid varied with the molecular size of the dibasic acid. The extent of incorporation in soy phospholipids was 4–13% in the case of adipic acid and 9–20% in the case of sebacic acid. The surface-active properties of these modified soy phospholipids were examined and were found to be different from those of the original (unmodified) soy phospholipid. The interfacial properties such as critical micelle concentration (CMC), γCMC, surface excess concentration Γmax, and minimum area per molecule (Å), and thermodynamic parameters such as standard free energy of micellization, were found to depend on the hydrophobic part of the dibasic acids. 相似文献
48.
Rinaldo Gregorio Luiz Francisco Malmonge Guilherme Fontes Leal Ferreira Wilson Nunes Dos Santos Luiz Henrique Capparelli Mattoso 《应用聚合物科学杂志》2003,87(5):752-758
The real (ε′) and imaginary (ε″) components of the complex permittivity of blends of PVDF [poly(vinylidene fluoride)] with POMA [poly(o‐methoxyaniline)] doped with toluenosulfonic acid (TSA) containing 1, 2.5, and 5 wt % POMA–TSA were determined in the frequency interval between 102 and 3 × 106 Hz and in the temperature range from ?120 up to 120°C. It was observed that the values of ε′ and ε″ had a greater increase with the POMA–TSA content and with a temperature in the region of frequencies below 10 kHz. This effect decreased with frequency and it was attributed to interfacial polarization. This polarization was caused by the blend heterogeneity, formed by conductive POMA–TSA agglomerates dispersed in an insulating matrix of PVDF. The equation of Maxwell–Garnett, modified by Cohen, was used to evaluate the permittivity and conductivity behavior of POMA–TSA in the blends. A strong decrease was observed in POMA–TSA conductivity in the blend, which was bigger the lower the POMA–TSA content in the blend. This decrease could have been caused either by the POMA dedoping during the blend preparation process or by its dispersion into the insulating matrix. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 752–758, 2003 相似文献
49.
Methanol synthesis from carbon dioxide hydrogenation was studied over ceria/-alumina- and yttria-doped ceria (YDC)/-alumina-supported copper oxide catalysts to seek insight into the catalysis at metal–support interfaces. It was found that, in comparison with Cu/-Al2O3, the Cu/CeO2/-Al2O3 and Cu/YDC/-Al2O3 catalysts exhibited substantial enhancement in activity and selectivity toward methanol formation. The extent of enhancement was augmented by increased ceria loading on -alumina and with increased yttria doping into ceria. The enhancement is inferred to result from the synergistic effect between copper oxide and surface oxygen vacancies of ceria. 相似文献
50.
The vacuum residual from Iranian Light crude oil are separated into a series of 16 narrow fractions according to the molecular weight by the supercritical fluid extraction and fractional (SFEF) technology. The chemical element and the UV spectrum of each fraction are analyzed. The effects of several factors on the interfacial tension are investigated, which are the fraction concentration in oil phase, the ratio of oil component, the salts dissolved in the water phase and the pH value. The interfacial tension decreases rapidly as the concentration of the residual fraction in the oil increases, showing a higher interfacial activity of the fraction. The interfacial tension changes, as the amount of absorption or the state of the fractions in the interface changes resulting from different ratios of oil, different kinds or concentrations of salts in water, and different pH values. It is concluded that the intrfacial tension changes regularly, corresponding to the regular molecular parameters of the vacuum residual fractions. 相似文献