摘要:

Drying of emulsions of special polymeric core-shell latexes results in structured films and coatings with advantageous material properties. Here, we focus on so-called “container particles”, consisting of a low viscosity core with a low glass transition (poly(2-ethylhexyl methacrylate), PEtHMA), covered by a thin shell of a cross-linked rubber (poly(n-butyl acrylate), PBA). These particles can be regarded as model emulsions of reactive polymeric oils with a very high colloidal stability. The film formation of these latexes was studied by atomic force microscopy (AFM) in the tapping mode as well as by transmission electron microscopy (TEM). It is shown that the films stay nanostructured after the drying process, i. e. they exhibit both a controlled topography as well as a network superstructure originating from the characteristics of the original dispersions.

ISSN:0193-2691    

DOI:10.1080/01932699908943785

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The droplet size distribution (DSD) of unstable water/oil dispersions has been studied with a new technique. The technique is based on a fast dilution of the dispersion injected into an analysis vessel where the DSD is analyzed with a video camera and a image analyzing tool. Dispersions generated with no pressure drop in the flow rig were compared to those generated with a pressure drop over a needle valve. The latter dispersion showed a much narrower DSD and a lower average droplet diameter. The results are from preliminary experiments in order to evaluate the method.

ISSN:0193-2691    

DOI:10.1080/01932699908943786

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Viscoelastic properties of heat-set whey protein emulsion gels containing active filler (protein-covered droplets) and inactive filler (surfactant-covered droplets) have been investigated at small and large deformations using a controlled stress rheometer. Data are reported as a function of protein concentration, oil volume fraction, and average emulsion droplet size. The active filler enhances the gel strength, whereas the inactive filler reduces the gel strength. The higher the elastic modulus of the protein gel matrix, the less the effect of the active filler, but the greater the effect of the inactive filler (andvice versa). Higher oil volume fraction and reduced particle size both intensify the effect of the filler. The large deformation behaviour of a heat-set protein gel or a heat-set emulsion gel containing up to 20 vol% oil is entropic in character, whereas an emulsion gel of higher filler content behaves more like a typical enthalpic particle gel.

ISSN:0193-2691    

DOI:10.1080/01932699908943787

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Stochastic model for oil emulsification in water has been deduced. The model in the form of differential equation was starting point to get various mathematical expressions and relations connecting different factors and parameters of the emulsification process and dispersion and Theological properties of the emulsion. Experimental investigations of particle size distribution, Theological behaviour and stability of great number of oil-in-water emulsions have been performed. The aim of the experimental investigations was to verify validity of the expressions derived. The validity of the derived expressions was checked not only for emulsions of different compositions, but also for the changes and phenomena at different stages of the emulsification process.

ISSN:0193-2691    

DOI:10.1080/01932699908943788

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A preparation of Ketamine [2-(Chlorophenyl)-2-(methylamino) cyclohexanone, C13H16ClNO, anesthetic agent] in oil in water multiple emulsion for prolonged drug release was formulated and evaluated. Ketamine, the cyclohexylamine, is used as a short-acting anaesthetic in humans and in some animal species [1]. Ketamine is poorly bound to plasma proteins and has a half-life of approximately 4 hours following intravenous injection [2]. Ketamine leaves the blood very rapidly to be distributed into the tissues with a high lipid solubility [2]. The recommended dosage of intravenous Ketamine is 2.5-20mg/kg [3]. The LD50 injected intraperitoneally in mice and rats is 100 times the intravenous and 30 times the intramuscular dose used in humans.

ISSN:0193-2691    

DOI:10.1080/01932699908943789

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The interaction between a phospholipid stabilized triglyceride emulsion and a hydrophilic silica surface has been studied at varying pH and electrolyte content using ellipsometry. The adsorbed amount decreases with pH and increases with increasing electrolyte content in the emulsion, and this can be rationalized on the basis of the electrostatic interaction between the emulsion droplet and the surface. The layer thickness, however, is essentially independent of these parameters.

ISSN:0193-2691    

DOI:10.1080/01932699908943790

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The vapor pressure data from previous publications of a model fragrance emulsion system consisting of water, an aromatic fragrance phenethyl alcohol, an aliphatic one limonene, and a nonionic surfactant Laureth 4, were used to calculate the variation in vapor pressures of both fragrances and water during free evaporation. The evaporation path in a three-dimensional four-component phase diagram was estimated from the vapor pressures.

ISSN:0193-2691    

DOI:10.1080/01932699908943791

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The role of asphaltenes in stabilizing water-in-crude oil emulsions is extremely well established. The mechanism appears to be one in which planar, disk-like asphaltene molecules aggregate through lateral intermolecular forces to form primary aggregates or micelles which are interfacially active. These aggregates — upon adsorbing at the oil-water interface — crosslink through physical interactions to form a viscoelastic network, which has been characterized by some as a “skin” or a “plastic film”. The strength of this film, as gauged by shear and elastic moduli, seems to correlate well with water-in-oil emulsion stability. What is still relatively unknown is the role of chemistry in governing the strength of these lateral inter-asphaltene interactions. The candidate interactions include π-bonding between the delocalized electrons in the fused aromatic ring core, H-bonding between proton donors and acceptors imbedded in the asphaltenic cores, and metal-electron interactions between, for example, heavy metal ions such as vanadium or nickel and electron pairs in pyrrolic or porphyrin functional groups. We have probed these interactions indirectly by studying thedestabilizationof water-in-oil emulsions by a variety of aromatic solvents. In this paper, we review our previous results on both water-in-crude oil systems, as well as water-in-model oil (heptane-toluene-asphaltene mixtures) systems, in which the emulsions were progressively destabilized by addition of aromatic solvents. We also present new results withfused ringaromatic solvents, specifically methyl-naphthalene, phenanthrene, and phenanthridine. Our results suggest that fused ring aromatic solvents are considerably more effective at destabilizing asphaltene emulsions and proton-accepting fused ring aromatic solvents aremosteffective. These results indicate that both π-bonding and H-bonding play significant roles in mediating the aggregation of asphaltenes in oil-water interfacial films.

ISSN:0193-2691    

DOI:10.1080/01932699908943792

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Video enhanced microscopy (VEM) enables direct investigation of dilute emulsions. A practical and effective preparative technique utilizes microslides, which are flat, rectangular microcapillaries made from borosilicate glass. Experimental difficulties due to droplet sedimentation and droplet-microslide wall interaction can be drastically reduced, even eliminated, by the use of low density contrast emulsions, i.e. emulsions where the densities of the dispersed and continuous phases are not very different. The dichlorodecane (DCD)-in-water emulsion is an example of such a system. This system.can as such be used for measurement of the time of theelementary act of coalescence, calculated from the evolution in the droplet size distribution. The developing distributions can be determined through automated VEM.

ISSN:0193-2691    

DOI:10.1080/01932699908943793

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Water transfer between water droplets and water + NaCl droplets dispersed within emulsions have been pointed out by differential scanning calorimetry. Using a solution- diffusion model, water fluxes have been calculated.

ISSN:0193-2691    

DOI:10.1080/01932699908943794

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor