Packing characteristics of sub-micron particles under van der Waals force and electrostatic force via discrete element method

Abstract

Benefiting from the large specific surface area and controllable physical behaviors, sub-micron sized polymer particles (100–1000 nm) have been fabricated as sensors, color displays and energy management devices. The formation mechanisms of sub-micron particles' structure are still not clear. In this work, a DEM model for sub-micron particles is built by applying van der Waals force and electrostatic force in the model. The packing patterns and porosity are validated with experimental results. The packing characteristics including packing patterns, porosity, coordination number (CN) and forces are examined. Clusters and chains structure is found for sub-micron particles, with large porosity but also large coordination number, different with the relationship of porosity and CN of micron particles. Meanwhile, the effect of separation distances and Ha constant and charge amount are investigated. Suitable separation distances for van der Waals force calculation are obtained for different sized sub-micron particles.