Effect of Amorphization on the Punch Sticking Propensity of Organic Powders

Powder adhesion to tooling surfaces during pharmaceutical tablet manufacturing can compromise product quality and lead to significant production inefficiencies. Although prior studies have assessed adhesive tendencies in relation to mechanical, particulate, thermal, and surface-chemical properties, these investigations have focused almost exclusively on crystalline materials, leaving the role of amorphization largely unexplored. In this work, using eight chemically diverse model compounds, we systematically investigate how amorphization influences the adhesion of organic powders to steel tooling under realistic compaction conditions and elucidate the underlying mechanisms. Gravimetric measurements for eight cases show that, relative to the crystalline form, amorphization either significantly reduces adhesion (six cases) or produces no measurable change (two cases). Particle morphology does not consistently account for these trends, whereas plasticity analysis reveals a shift in the dominating adhesion mode from contact area-controlled adhesion to contact strength-controlled adhesion. At the molecular level, X-ray photoelectron spectroscopy indicates that amorphization alters the distribution of surface-exposed functional groups that interact with the oxygen-terminated iron oxide layer on steel tooling, leading to differences in adhesion to punch tips. Collectively, these results establish the important role of amorphization-induced changes in surface chemistry in governing powder-tool adhesion and provide a mechanistic framework for understanding adhesion between organic powders and metal surfaces during tablet compression.