Kinetics of elastic recovery in roll compaction

Elastic recovery ( $$ ) has been investigated and discussed extensively in the field of tableting. However, until now only limited data is available regarding $$ in roll compaction. Therefore, a previously established in-line measurement technique was rolled out to further investigate the kinetics of $$ in roll compaction and the effects of specific compaction force ( $$ ) and roll speed ( $$ ). In-line laser triangulation measurements at different positions within a roll rotation as well as measurement over time after the process has been stopped were utilized. Pure microcrystalline cellulose ( $$ ) and two placebo powder blend formulations were analysed. Successful fit of the contained $$ profiles emphasized that the $$ on the roll surface is build out of two exponential kinetics. Starting with a dominating fast $$ ( $$ ), characterized by a high increase of the ribbon thickness after passing the gap width, followed by a slower $$ ( $$ ). Sigma minus plot analysis showed that increasing $$ led to an accelerated $$ and $$ which was related to the viscoelastic behaviour of $$ . The $$ only had an effect on the kinetics of $$ if a brittle filler was added to the mixture. The conducted study established the first approach in literature to characterize the kinetics of $$ in roll compaction. It supports the understanding and characterization of relaxation times and the effect of the $$ and $$ in roll compaction.