(93y) An Experimental Approach to Quantify Cohesion of Powders

In the pharmaceutical industry, the importance of particle technology has been relatively neglected. Particle technology, which makes up the majority of pharmaceutical manufacturing, is in crucial need of upgrade. As pharmaceutical products become more complex, better manufacturing technology is required to ensure product uniformity and performance. Shear plays an important role in the processing of pharmaceutical blends, affecting the performance of mixtures as well as their scale-up requirements. However, in spite of its significant impact, shear has not been studied systematically. Better manufacturing technology requires better understanding and control of product properties and process attributes. The cohesive strength and friction coefficient of granular materials are examples of such properties, and can be analyzed by shear testers. Several shear testers have been developed to analyze the flow properties of granular materials. In this poster, I will be using two different methodologies to characterize flow properties of cohesive granular material. First, the ?controlled shear? Rheometer is designed to examine the effects of shear rate and total shear on pharmaceutical powder blends. Common pharmaceutical excipients and their mixtures are used for this experiment. The data collected from the sheared powder blends generally showed an increase in cohesion with an increase of applied shear and thus and increase in ?bulk density?. The second methodology utilizes the Gravitational Displacement Rheometer (GDR) to analyze the effects of moisture and lubricant on flow properties of pharmaceutical powders. The GDR consists of a rotating cylinder mounted on top of a load cell. As the cylinder rotates, the powder blend will continuously exhibit characteristic avalanches which are measured by the load cell. As the powder cohesion increased the lubricant played a major role in affecting the flow properties of the powders. On the other hand, introducing liquid in the system in the form of moisture showed variable effects for different materials. In some instance, adding moisture to the system increased cohesion, whereas in other cases, it had an opposite effect. The GDR was also used to quantify the results obtained from the ?Controlled Shear Rheometer?.