The structure elucidation of semisolid w/o emulsion systems

Abstract

In the course of investigating the effects of silicone surfactant (Abil WE 09 ®) on the microstructure of semisolid w/o emulsion systems with different water/oil ratios, only dispersed droplets of the internal water phase (1–15 μm size) were discovered in the gel network of white petrolatum. With increasing water content (from 40 to 90% w/w) the degree of dispersity was found to increase (microscopic analysis-polarized light microscopy and TEM). Experiments were also carried out using differential scanning calorimetry (DSC) and rheometry (rotational and oscillatory viscosimetry). The DSC results showed different behaviour of the investigated systems on controlled cooling. In semisolid emulsion systems with droplets small enough and of equal size, a homogeneous nucleation temperature was achieved. In emulsion systems containing a high percentage of water, the assumption that the behaviour of water was like that of the pure (bulk) water was acceptable. All semisolid emulsion systems exhibited pseudoplastic behaviour. Their viscoelastic properties determined using oscillation rheometry correlated well with rotational results.