Study of the gastrointestinal diffusion system (GDS): influence of acacia gum on mechanical and chemical properties in free cellulose acetate films.

In this work a study of free cellulose acetate films was carried out in the presence and absence of acacia gum at high concentrations (50 and 75%). The mechanical toughness and the aspect were influenced by operatory conditions and by the relative air humidity. The increase of relative humidity from about 0% to 75% decreased the mechanical toughness and the color film changed from a clear to opaque white. The presence of acacia gum decreased the mechanical toughness and the water vapour transmission rate and increased the film water solubility.

Quantitative mineralogical composition of complex mineral wastes--contribution of the Rietveld method.

The objective of the work presented in this paper is the quantitative determination of the mineral composition of two complex mineral wastes: a sewage sludge ash (SSA) and a municipal solid waste incineration fly ash (MSWIFA). The mineral compositions were determined by two different methods: the first based on calculation using the qualitative mineralogical composition of the waste combined with physicochemical analyses; the second the Rietveld method, which uses only X-ray diffraction patterns. The results obtained are coherent, showing that it is possible to quantify the mineral compositions of complex mineral waste with such methods. The apparent simplicity of the Rietveld method (due principally to the availability of software packages implementing the method) facilitates its use. However, care should be taken since the crystal structure analysis based on powder diffraction data needs experience and a thorough understanding of crystallography. So the use of another, complementary, method such as the first one used in this study, may sometimes be needed to confirm the results.