Profoundly improving flow properties of a cohesive cellulose powder by surface coating with nano-silica through comilling

Sayantan Chattoraj, Limin Shi, Changquan Calvin Sun

Research output: Contribution to journalArticlepeer-review

86 Scopus citations


Poor flow properties hinder the easy handling of powders during industrial-scale processing. In this work, we show that powder flow can be substantially improved by reducing the cohesion of powders by coating them with nanosized guest particles. We further show that comilling is an efficient process for nanocoating. We have systematically investigated the effects of total number of comilling cycles (10-70 cycles) and silica loading (0-1.0wt %) on the flow behavior of a highly cohesive and poorly flowing grade of microcrystalline cellulose powder (Avicel PH105). Optimum flow enhancement has been achieved with 1.0wt % silica loading at 40 comilling cycles. The flow properties of nanocoated Avicel PH105 are comparable to those of Avicel PH102, which exhibits adequate flowability for processing on a high-speed tablet press. Comilling is fast and suitable for continuous processing. It shows potential for addressing industrial powder handling problems caused by poor powder flow properties.

Original languageEnglish (US)
Pages (from-to)4943-4952
Number of pages10
JournalJournal of Pharmaceutical Sciences
Issue number11
StatePublished - Nov 2011

Bibliographical note

Funding Information:
This work was supported by a Grant from PhRMA foundation. We thank Dr. Yushi Feng of Eli Lilly and Company, Indianapolis, Indiana, for the SSA and PSD studies. We thank Prof. Jesse Zhu of Western Ontario, Canada, for useful discussion that inspired this work. The SEM studies were carried out at the Institute of Technology Characterization Facility, University of Minnesota.


  • Coating
  • Comilling
  • Excipients
  • Materials science
  • Microcrystalline cellulose
  • Nanotechnology
  • Powder flow
  • Processing
  • Silica


Dive into the research topics of 'Profoundly improving flow properties of a cohesive cellulose powder by surface coating with nano-silica through comilling'. Together they form a unique fingerprint.

Cite this