Effect of surface compositional difference on powder flow properties

Surface composition plays an important role in the cohesion/adhesion behavior of powders. Yet, the quantification of the major factors that affect powder kinematics is a challenge because of the surface composition heterogeneity of granular materials. This study aims to understand the mechanisms tha...

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Bibliographic Details
Published in:Powder technology 2019-02, Vol.344, p.363-372
Main Authors: Jange, Camila G., Ambrose, R.P. Kingsly
Format: Article
Language:English
Subjects:
Beads
Bulk density
Butter
Coating
Coatings
Cohesion
Composition
Compressibility
Corn
Dilatancy
Dynamic stability
Flow stability
Food composition
Glass beads
Gluten
Granular materials
Heterogeneity
Kinematics
Molasses
Organic chemistry
Performance indices
Powder
Properties (attributes)
Shear flow
Silica
Silicon dioxide
Stability analysis
Starch
Surface chemistry
Wheat
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Summary:Surface composition plays an important role in the cohesion/adhesion behavior of powders. Yet, the quantification of the major factors that affect powder kinematics is a challenge because of the surface composition heterogeneity of granular materials. This study aims to understand the mechanisms that drive cohesiveness in dry powders by evaluating the bulk flow performance of uniform size glass beads coated with distinct chemical components. Silica beads of 125, 180, and 250 μm were coated with corn starch, molasses, butter, or wheat gluten to reproduce the surface composition of food powders. Particle size and shape distributions, dynamic flow properties, shear flow properties, and compressibility profile of the coated materials were evaluated and compared with uncoated silica beads. The stability index, a dynamic flow property, ranged from 0.9 to 1.1 for all samples, which indicated a stable flow. Surface modified powders showed increasing bulk cohesion and higher compressibility indexes in comparison with the control samples. Specifically, butter and molasses coated powders had the highest specific energy, cohesion, and compressibility indexes, primarily, due to the higher magnitude of interparticle interactions, lower bulk densities, and poor bed dilatancy. This study provides quantitative understanding on powder flow that will be important for smoother powder processing operations in which the surface compositional difference is of major interest such as hopper discharge, high shear mixing, and tablet compaction processes. [Display omitted] •Surface chemistry variation significantly influences the bulk properties and particle properties of powders.•Stress levels, moisture uptake, and bulk properties have significant effect on powder flow.•The strength of interparticle interaction is affected by particle's surface chemical composition.•The angle of internal friction provided cogent description of powder bed dilation in the cohesive powder systems.
ISSN:0032-5910
1873-328X
DOI:10.1016/j.powtec.2018.12.027