Method to determine envelope density for roller compacted ribbons by solid displacement of glass microspheres

The envelope density of the roll-compacted ribbon is a widely accepted physical property that serves as a criterion for the transferability of dry granulation processes. Existing methods of obtaining ribbon density data have drawbacks in their reliability and availability at production facilities. A novel method is proposed in this paper and the performance thereof is compared to other established techniques. A pilot study was conducted on several roller compactors to prepare various batches of ribbons under different process parameters using model and real formulations from the industry. The presented method measures the envelope volume of roll-compacted ribbons by solid volume displacement of glass microspheres. The solid displacement method for measuring envelope density is as precise as mercury porosimetry, provided that the ribbon quality is adequate, even in the presence of minor structural failures, it is nondestructive allowing sample reuse, and it is scalable to larger ribbon sizes.