Solid bridge formation between spray-dried sodium carbonate particles

Mark Leaper, D.C. Prime, P.M. Taylor, V. Leach

Research output: Contribution to journalSpecial issuepeer-review


Moisture migration caking of pharmaceutical excipients in the absence of load is a significant quality and stability issue. This study uses Atomic Force Microscopy (AFM) to examine a solid bridge formed between two 20µm spray-dried sodium carbonate particles. The bridge is grown by repeatedly exposing the system to 70% RH and 30% RH cycles at 25?C. A comparison is made with the idealised bridge model developed by Tanaka (1978) which was previously verified using crystalline systems. The resulting system was found to be more complex and grew in two stages. The first stage consisted of linear growth to 5 cycles, followed by a more gradual expansion and the appearance of crystalline structures.
Original languageEnglish
Pages (from-to)1008-1013
Number of pages6
JournalDrying Technology
Issue number9
Publication statusPublished - 29 May 2012


  • Atomic Force Microscopy
  • caking
  • sodium carbonate
  • spray-drying


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