Track: Manufacturing and Analytical Characterization - Chemical - Drug Product Manufacturing and Development - Other
Category: Late Breaking Poster Abstract
Surface Preparation and Its Effect on Sticking
Purpose: The purpose of this work was to evaluate the powder to metal adhesion, or sticking, behavior of mannitol, acetylsalicylic acid, starch 1500, and ibuprofen following surface preparation of a clean metal punch and an aged punch tip. Sticking was characterized using a newly designed instrument that consists of a non-contact laser sensor along with surface contact angle analysis and measurements of adhered weight. Methods: A removable upper punch tip was buffed using Simichrome paste and a cotton swab. The tip was then sonicated for 5 minutes using a soap solution and two sonication steps using deionized water. The punch surface was dried using compressed argon. Mannitol tablets was compacted to 168 MPa targeting an in-die relative density of 90% using the clean upper punch tip. Acetylsalicylic acid and Ibuprofen tablets was compacted to 56 MPa targeting an in-die density of 95%. Starch 1500 was compacted to 84 MPa targeting an in-die density of 90%. Sticking on the punch surface was analyzed using the non-contact laser sensor. A photograph of the upper punch tip was taken and the punch tip was weighed. This experiment was then repeated for punch tips that were aged by being stored under 55% relative humidity conditions for 1, 4, 24, and 72 hours. In addition, contact angle measurements of the surface at various stages of preparation was taken. Results: Contact angle measurements of the punch surface indicated a transition from a hydrophilic surface immediately after cleaning to a hydrophobic surface when aged. Laser results showed high sticking immediately after cleaning and a reduction of sticking with storage time for most materials. Mannitol showed the highest dependence on surface conditions while Ibuprofen showed the least dependence. Conclusion: In this work, we have shown that sticking can be highly dependent on the state of the punch surface. Sticking was decreased after the punch tip was exposed to ambient atmospheric conditions thus indicating the complex nature of adhesion measurements.