Prediction of inter-particle adhesion force from surface energy and surface roughness

Laila J. Jallo, Yuhua Chen, James Bowen, Frank Etzler, Rajesh Dave

Research output: Contribution to journalArticlepeer-review

51 Scopus citations

Abstract

Fine powder flow is a topic of great interest to industry, in particular for the pharmaceutical industry; a major concern being their poor flow behavior due to high cohesion. In this study, cohesion reduction, produced via surface modification, at the particle scale as well as bulk scale is addressed. The adhesion force model of Derjaguin-Muller-Toporov (DMT) was utilized to quantify the inter-particle adhesion force of both pure and surface modified fine aluminum powders (∼8 μm in size). Inverse Gas Chromatography (IGC) was utilized for the determination of surface energy of the samples, and Atomic Force Microscopy (AFM) was utilized to evaluate surface roughness of the powders. Surface modification of the original aluminum powders was done for the purpose of reduction in cohesiveness and improvement in flowability, employing either silane surface treatment or dry mechanical coating of nano-particles on the surface of original powders. For selected samples, the AFM was utilized for direct evaluation of the particle pull-off force. The results indicated that surface modification reduced the surface energy and altered the surface nano-roughness, resulting in drastic reduction of the inter-particle adhesion force. The particle bond number values were computed based on either the inter-particle adhesion force from the DMT model or the inter-particle pull-off force obtained from direct AFM measurements. Surface modification resulted in two to three fold reductions in the Bond number. In order to examine the influence of the particle scale property such as the Bond number on the bulk-scale flow characterization, Angle of Repose (AOR) measurements were done and showed good qualitative agreements with the Bond number and acid/base surface characteristics of the powders. The results indicate a promising method that may be used to predict flow behavior of original (cohesive) and surface modified (previously cohesive) powders utilizing very small samples, and that the surface modification can drastically improve the powder flow for industrially relevant materials.

Original languageEnglish (US)
Pages (from-to)367-384
Number of pages18
JournalJournal of Adhesion Science and Technology
Volume25
Issue number4-5
DOIs
StatePublished - Jan 1 2011

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Mechanics of Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

Keywords

  • Inverse gas chromatography
  • acidity and basicity
  • bond number
  • cohesion reduction
  • inter-particle adhesion force
  • powder flow
  • surface energy
  • surface modification

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