摘要:

The theoretical interpretation of experimental data from the previous papers (1,2) are extended with the purpose to demonstrate the possibilities of a qualitative characterisation of flocculated emulsions by means of dielectric spectroscopy.

ISSN:0193-2691    

DOI:10.1080/01932699408943567

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Water-in-oil model emulsions with various amounts of the aqueous phase, i.e. 24 to 74 % by volume and with 4% NaCl, have been characterized by means of time domain dielectric measurements in the frequency region 50 MHz to 2 GHz. The measurements were carried out in a flow loop which made it possible to do the characterization of the emulsions both under flow and at rest. The flowing emulsions show in general lower static permittivities than the corresponding emulsions at rest. The dielectric data are explained by models involving a flocculation of the aqueous droplets. The result indicate just a small deviation from sphericity of the formed floes.

ISSN:0193-2691    

DOI:10.1080/01932699408943568

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Dielectric properties of concentrated w/o emulsions in the frequency range 40 MHz to 4 GHz were investigated by means of the time domain spectroscopy (TDS) method in the presence of an external high voltage field. All investigated samples show a dielectric dispersion due to the interfacial polarization inside the aqueous droplets. All the dielectric parameters (εs, εs−εinfinand τ) are dependent on the magnitude of the external field. At higher electric fields, the coalescence is promoted. The dependence of the droplet size distribution, the strength of the applied field, the orientation of the droplets relative the electrical field on the dielectric parameters is discussed for these concentrated emulsions.

ISSN:0193-2691    

DOI:10.1080/01932699408943569

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The hydrocarbon rich phase (L2) of the system trichlorofluoromethane CCl3F / water (electrolyte) / nonionic surfactant has been investigated by means of NMR self-diffusion measurements, and dielectric spectroscopy. The dielectric spectra were recorded between 50 MHz and 5 GHz and fitted to a Cole-Cole model function with an additional Debye term. The main relaxation was due to a polarization inside the aqueous droplets (Maxwell-Wagner-Sillars relaxation). The NMR self-diffusion data display a low molecular self-diffusion for both water and surfactant over a broad interval consistent with a droplet structure. However at the highest CCl3F concentrations the rapid diffusion of the nonionic surfactant reveals that the aqueous droplets are most likely stabilized by means of gas hydrates at the w/o microemulsion interface.

ISSN:0193-2691    

DOI:10.1080/01932699408943570

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Interactions between monolayers of trilaurylamine (TLA) and various water-soluble corrosion, hydrate and scale inhibitors, as well as acetic acid and FeCl2, have been studied by means of the Langmuir technique, The water-soluble compounds were present in the subphase before TLA was spread. Their influence on the monolayer properties were measured by means of surface pressure-area ( k-A) isotherms and constant surface pressure-area relaxation measurements. All the added water soluble species gave rise to monolayer expansion. The monolayer expansion observed for TLA at pH 1, increased when FeCl2was added to the subphase at the same pH. Polyethyleneglycols with molecular weight higher than 200 destabilized totally the TLA-monolayer, probably due to bending and folding into multilayers. Monolayer expansion and film instability increased with increased acetic acid concentrations. The destabilization mechanism in this case was most likely due to a combination of nucleation and dissolution of film components into the subphase. The corrosion inhibitor Dyno KI 384 had a higher surface activity than TLA. Hence the monolayer

ISSN:0193-2691    

DOI:10.1080/01932699408943571

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Room temperature glass containing copper nitrate was produced using the microemulsion-gel method. Ultraviolet-visible spectroscopy and x-ray diffraction spectra were used to demonstrate the presence of copper nitrate in the gel samples. The samples were examined using optical microscopy, with and without polarized filters, and scanning electron microscopy with energy dispersive x-ray analysis, before and after the extraction of the surfactant with an organic solvent. The results indicated that copper nitrate was present throughout the silicate network formed and was associated with the microemulsion components, i.e., the interstitial liquid, remaining in the bulk material.

ISSN:0193-2691    

DOI:10.1080/01932699408943572

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0193-2691    

DOI:10.1080/01932699408943566

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor