Yield stress of semisolid preparations

CHARLES UNIVERSITY Faculty of Pharmacy in Hradec Kralove Department of Pharmaceutical technology Name of the student: Marta Šmídová Title of diploma thesis: Yield stress of semisolid preparations Consultant: PharmDr. Eva Šnejdrová, Ph.D. The diploma thesis deals with rheological properties, particularly yield stress, of pharmaceutical semi-solid excipients and preparations. The theoretical part summarizes the research knowledge of rheological behaviour of semi-solids, specifically yield stress, and it also describes selected materials. In the experimental part the rheological properties of semi-solid excipients were measured using the Kinexus pro + rheometer at 25 ř C and the results were subsequently evaluated by the rSpace software. The flow and viscosity curves were determined by the Toolkid_V001 Shear Rate Table at range of 0.1-100.0 s-1 and plotted by the Power law model fit. The course of these curves shows non-Newtonian behaviour exhibiting a plastic flow. The yield stress was measured by sequence Viscometry_0002 Shear stress ramp at the shear stress range 0.1-100/300 s-1 and evaluated by the Yield stress analysis. Adeps lanae revealed the lowest value of yield stress, Cremor leniens had the highest value yield. The used test seems to be suitable for comparison of flow properties of..