Rheology

Rheology is the study of the flow (strain rate) and deformation (strain) of materials and provides information regarding how far a material moves when under a defined external force or stress. A rheometer can be used to measure Newtonian materials, which do not change with strain rate, as well as non-Newtonian materials where the viscosity changes with an applied strain rate. The technique can be used for liquids, ‘soft solids’ or solids under conditions in which they respond with plastic flow rather than deforming elastically in response to an applied force. The rheometer uses a specified geometry (such as cone and plate), a controlled temperature environment (such as a Peltier plate), and a motor to apply a specified stress, strain, or strain rate to the sample of interest.

Impact Analytical’s rheometer has been qualified for use in compliance with: U.S. Food and Drug Administration’s (FDA) current Good Manufacturing Practices (cGMP) Regulations, 21 CFR Parts 210 and 211, and the United States Pharmacopeia (USP).

Examples

Gel samples were obtained from a manufactured product. The viscosity of the gels was determined versus a specified strain rate under controlled temperature conditions. This information was used to assist in the manufacturing process.
A raw material was analyzed over a period of time under a specified temperature and strain rate to obtain a viscosity at specific time points. These data were used as acceptance criteria for the raw material.