[Thermal stability evaluation of some W/O/W double emulsions containing 1% piroxicam by rheological measurements]. / Evaluarea stabilitatii termice a unor emulsii duble H/L/H cu piroxicam prin determinari reologice.

UNLABELLED: The aim of this work was to evaluate thermal stability of some W/O/W concentrated double emulsions (with 80% dispersed phase) containing 1% piroxicam following their theological behaviour at various temperatures. W/O/W double emulsions containing 1% piroxicam were prepared using the two-step procedure. RESULTS: The variable parameter of formulations was the hydrophilic macromolecule compound dispersed in the internal and external aqueous phases (hydroxyethylcellulose and Carbopol 940). Rheological behaviour and viscosity of the obtained W/O/W double emulsions was measured at 15 degrees C, 20 degrees C, 25 degrees C, 30 degrees C and 35 degrees C respectively, after preparation. The obtained results demonstrated that the studied W1/O/W2 double emulsions containing 1% piroxicam were stable under applied thermal stress, although they exhibited some differences in rheological properties caused by formulation variable.

Particle size analysis of some water/oil/water multiple emulsions.

Particle size analysis gives useful information about the structure and stability of multiple emulsions, which are important characteristics of these systems. It also enables the observation of the growth process of particles dispersed in multiple emulsions, accordingly, the evolution of their dimension in time. The size of multiple particles in the seven water/oil/water (W/O/W) emulsions was determined by measuring the particles size observed during the microscopic examination. In order to describe the distribution of the size of multiple particles, the value of two parameters that define the particle size was calculated: the arithmetical mean diameter and the median diameter. The results of the particle size analysis in the seven multiple emulsions W/O/W studied are presented as histograms of the distribution density immediately, 1 and 3 months after the preparation of each emulsion, as well as by establishing the mean and the median diameter of particles. The comparative study of the distribution histograms and of the mean and median diameters of W/O/W multiple particles indicates that the prepared emulsions are fine and very fine dispersions, stable, and presenting a growth of the abovementioned diameters during the study.