Emulsions, atomic spectroscopy

The power of optical spectroscopies is that they are often much better developed than their electron-, ion- and atom-based counterparts, and therefore provide results that are easier to interpret. Furtlienuore, photon-based teclmiques are uniquely poised to help in the characterization of liquid-liquid, liquid-solid and even solid-solid interfaces generally inaccessible by other means. There has certainly been a renewed interest in the use of optical spectroscopies for the study of more realistic systems such as catalysts, adsorbates, emulsions, surfactants, self-assembled layers, etc. 

The effect of the Tg of the latex on the film-formation behaviour of a series of 2-ethylhexyl acrylate/methyl methacrylate emulsion copolymers was studied. Stage 1 of fihn formation was examined using a combination of DMA and conductivity measurements. Stages 2 and 3 were investigated using calorimehic compensation, DSC, dielectric spectroscopy and atomic force microscopy. Comparison of the results from the different methods employed led to a detailed model of the film-formation process in which the temp, used relative to the minimum film-formation temp, determined the effectiveness of the processes. The relative usefulness of the techniques used in their ability to characterise the various stages in the film-formation process was assessed for these copolymer systans. 23 refs. 

In the previous sections, the impact of the material properties of emulsions and spray process parameters on the dispersion was described. It provided information about the dispersion of secondary droplet of DE, rather than the release of an encapsulated component. The release of functional components during spray processing may also be influenced by shear-induced diffusion and osmotic pressure. Therefore, an iron-salt (FeS04) encapsulated DE was sprayed and the retained amount of iron in the sprayed emulsion detected. Conductivity and Atomic Adsorption Spectroscopy (AAS) methods were used for measuring the concentration of iron. The retained amount of iron is defined as follows (23.15) ... 

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