摘要:

The synthesis of the nonylphenol poly(ethylene carbonate) surfactants derived from nonylphenol (NP), carbon dioxide and ethylene oxide (EO) were carried out with high yields in the presence of alkali metal salts (K2CO3, Na2CO3, K2SnO3and zinc glutamate) as base catalysts. The synthesis reactions were carried out in a stainless-steel reactor in the temperature range of 150-200°C under an initial pressure of 800 psi, with an initial molar ratio of CO2/EO = 0·21, catalyst concentration of 1 × 103M for a 24 h-period. The surfactants were characterized by FT-IR and by H-NMR. The percentages of carbon dioxide incorporation were between 7 and 16% indicating that the activation of CO2is a rather difficult process under the catalytic conditions used L175-200 °C and 800 psi of final pressure)

ISSN:0193-2691    

DOI:10.1080/01932699608943508

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

We investigated the relationship between the macroscopic viscosity lpar;ηN), determined by creep measurement, and the microscopic viscosity, estimated by rotational correlation time (τc) of spin label determined by ESR method, for wheat and potato starch gels. Both ηNand τc. Of wheat starch gel increased linearly with an increase of starch concentration. Both ηNand τcof potato starch gel increased exponentially with an increase of starch concentration. The τcof wheat starch gel related linearly to the ηNof the gel at 30, 40 and 50°C. For potato starch gels, the τc.also related significantly to the ηNat 30, 40 and 50°C. The τcof free BrAcTEMPO was much smaller than that of spin-labeled AcTEMPO in wheat starch gel. It is concluded that the change in microscopic viscosity of starch gels agrees with their change in macroscopic viscosity.

ISSN:0193-2691    

DOI:10.1080/01932699608943509

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The Raman spectrum of a surfactant is dominated by the vibrational modes of the hydrocarbon chain. The C-H stretching region &lpar;2800–3000thinsp; cm−1) is very sensitive to the lateral order of the molecule and the microenvironment of surfactant systems. The study of the phase diagram of the dodccyl bctaine, 1-butanol, water system and the microstructurc of surfactant solutions studied by their Raman spectra has helped us to discover an important new parameter. We regard this parameter (R’ = I2910/ I2910l288a) as a phase verification for surfactant systems, in which R1> 1 indicates the presence of lamellar liquid crystal and R’ < 1 indicates a micellar solution.

ISSN:0193-2691    

DOI:10.1080/01932699608943510

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This paper deals with the investigation on the influence of four amphiphile monolayers viz. arachidic acid, a mixture of dioctadecyl amine and arachidic acid (3:1(, carboxybetaine and dioleoyl-L-a-lecithin (DOPC) on ammonium nitrate crystallization. The study was carried out by means of surface pressure vs. area, surface potential vs. area and fluorescent microscopy. Results indicated a strong effect on ammonium nitrate crystallization in the presence of carboxybetaine and dioctadecylamine monolayers, whereas an inhibition in crystal growth was observed in the presence of DOPC.

ISSN:0193-2691    

DOI:10.1080/01932699608943511

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Extraction rates of lactic acid from aqueous solutions using Alamine 336 dissolved in toluene have been studied by the single drop technique. Interfacial tensions as a function of extractant concentration and initial extraction rates as a function of lactic acid and Alamine 336 concentrations are repotted. Assuming the extraction takes place by an interfacial reaction mechanism, a mass transfer model is proposed for lactic acid reactive extraction. The model assumes a mixed regime, in which the slow diffusion transport of the amine extractant to die inner drop interface, and its protonation at the interface are the rate controlling steps. The influence of a synthetic anionic surfactant, sodium n-dodecyl sulphate, on the extraction process has been also studied. For surfactant concentrations above the specific CMC (critical micelle concentration), the surfactant increases the overall mass-transfer rate up to 40%. The surfactant influence on the extraction kinetics is described on the basis of increasing the interfacial potential and the resulting rise of the proton concentration at the interface.

ISSN:0193-2691    

DOI:10.1080/01932699608943512

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

From the interfacial tension of organic compounds with water and their contactable surface areas, the aqueous solubility of such compounds can be quantitatively predicted. Vice-versa. when the interfacial tension with water is known for a given organic compound, as well as its aqueous solubility, its contactable surface area can be obtained. From any two of these three data, and the compound's surface tension, its free energy of hydration can be calculated. However the free energy of hydration is not simply linked to a compound's aqueous solubility. For compounds which are partly apolar and partly polar, the interfacial tensions with water must be separately determined for each part; once these are expressed in kT units, they can be added together, following which the aqueous solubility of the complete compound can be calculated (a procedure which has been used earlier to obtain the critical micelle concentrations of nonionic1and anionic2surfactants). From a comparison between the solubilities (and the interfacial tensions) of alcohols and those of the corresponding hydrocarbons, it is possible to obtain the (repulsive) free energy of OH-groups interacting in water, as well as the free energy of hydration of the OH-group of alcohols. The latter is about -5·6kT, or -14kJ/Mole.

ISSN:0193-2691    

DOI:10.1080/01932699608943513

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0193-2691    

DOI:10.1080/01932699608943514

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor