Assessment of Tribo-charging and Continuous Feeding Performance of Direct Compression Grades of Isomalt and Mannitol Powders

Michela Beretta, Julia Kruisz, Theresa R. Hörmann-Kincses, Viktoria Magosi, Meishan Guo, Majid Naderi, Sarah Heupl, Johann Kastner, Martin Spoerk, Amrit Paudel

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Tribo-charging is often a root cause of mass flow deviations and powder adhesion during continuous feeding. Thus, it may critically impact product quality. In this study, we characterized the volumetric (split- and pre-blend) feeding behavior and process-induced charge of two direct compression grades of polyols, galenIQ™ 721 (G721) for isomalt and PEARLITOL ® 200SD (P200SD) for mannitol, under different processing conditions. The feeding mass flow range and variability, hopper end fill level, and powder adhesion were profiled. The feeding-induced tribo-charging was measured using a Faraday cup. Both materials were comprehensively characterized for relevant powder properties, and their tribo-charging was investigated for its dependence on particle size and relative humidity. During split-feeding experiments, G721 showed a comparable feeding performance to P200SD with lower tribo-charging and adhesion to the screw outlet of the feeder. Depending on the processing condition, the charge density of G721 ranged from -0.01 up to -0.39 nC/g, and for P200SD from -3.19 up to -5.99 nC/g. Rather than differences in the particle size distribution of the two materials, their distinct surface and structural characteristics were found as the main factors affecting their tribo-charging. The good feeding performance of both polyol grades was also maintained during pre-blend feeding, where reduced tribo-charging and adhesion propensity was observed for P200SD (decreasing from -5.27 to -0.17 nC/g under the same feeding settings). Here, it is proposed that the mitigation of tribo-charging occurs due to a particle size-driven mechanism.

Original languageEnglish
Article number91
Pages (from-to)91
JournalAAPS PharmSciTech
Issue number4
Publication statusPublished - 28 Mar 2023


  • continuous manufacturing
  • isomalt
  • mannitol
  • tribo-charging
  • twin-screw powder feeding
  • Powders/chemistry
  • Particle Size
  • Technology, Pharmaceutical
  • Mannitol


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