This annual report summarizes progress made during the first year of the renewal project period (September 2024 - August 2025). Building upon the significant accomplishments from the initial three-year project (FRR-107-03, 2021-2024), this renewal phase addresses critical gaps identified by industry liaisons and extends mechanistic understanding of flow aid processibility and coating quality across various processing devices and intensities.
Major accomplishments:
Model development: accounting for guest particle aggregation
• Extended Chen's multi-asperity contact model to account for flow aid aggregation rather than assuming ideal monolayer deposition
• Developed mechanistic framework to account for non-uniform flow aid distribution and its aggregation, distinguishing effects of aggregates of flow aid via fractal analysis
• Analyzed effects of aggregation via spherical versus fractal aggregate structures and their differing impacts on cohesion reduction
• Incorporated fractal dimension analysis to relate aggregate size, porosity, and number of primary particles
• Quantified how aggregation reduces effective surface area coverage (SAC) and diminishes cohesion reduction by up to one order of magnitude
• Established relationship between coating device intensity and how differing aggregation effects for different shear imparted by nature of device
Coating device performance evaluation
• Evaluated three coating devices across shear intensity (low to very high shear) and operating mode (batch vs continuous):
o V-blender (low intensity, batch)
o Comil (medium intensity, continuous)
o LabRAM (high intensity, batch)
• Identified best processing parameters for each device type and compared their performance
• Demonstrated that higher shear creates better particle dispersion while lower shear results in nonuniform dispersion and significant aggregation; however, there is an optimum of high shear as well
• Validated model predictions with experimental coating quality analysis via SEM
Pilot scale validation and investigating effects on downstream processibility
• Tested the scalability of dry coating to pilot scale using Comil-U10 (10-20X scale-up)
• Assessed the impact of coating quality on downstream processing operations:
o Feedability assessment showing a dramatic reduction in feeding variability
o Tabletability studies across three drug loading formulations
o Weight variability reduction due to improved feeding consistency
• Demonstrated that coating quality directly impacts product attributes (downstream processibility)
Expanded flow aid (metal oxide based) testing beyond nano-silica flow aids
• Initial validation of metal oxide flow aids (Al₂O₃ and TiO₂)
• Achieved comparable flow enhancements to nano-silica coatings
• Established material property database including size, density, surface energy, and surface chemistry for metal oxide alternatives
Critical advances in mechanistic understanding:
The project has successfully addressed key limitations in guest particle coating assumptions. Previous models assumed uniform, monolayer coating; however, experimental evidence clearly showed that processing device intensity significantly affects flow aid aggregation state. The developed models now account for:
1. Aggregate size effect (Primary): Larger aggregates reduce effective SAC and shift contact regime transitions
2. Aggregate morphology effect (Secondary): Compact spherical aggregates perform better than porous fractal structures
3. Device intensity relationship: Processing intensity determines fractal dimension and porosity of resulting aggregates
These advances enable mechanistic understanding of device performance on bulk property improvement while coating with flow aids, moving beyond benchmarking with LabRAM to predictive guidance for scalable devices like V-blender and Comil.
Industry relevance:
This work provides IFPRI members with:
• Mechanistic understanding for selecting appropriate coating devices based on desired coating quality
• Framework explaining performance variations across different processing equipment
• Validated pilot-scale demonstration of scalability and downstream processing benefits
• Expanded flow aid selection beyond silica to include metal oxides
Next steps:
The coming year will focus on:
1. Completing metal oxide flow aid characterization and coating validation
2. Investigating mixing synergy when flow aid-coated material is blended with uncoated components