Formation of hollow granules from liquid marbles: Small Scale experiments

Research into formation of hollowgranules fromliquidmarbles is an emerging field in hydrophobic granulation. A liquidmarble is formed by a network of self-assembled hydrophobic powder around a droplet, and this paper investigates the conditions required for forming hollow granules from a liquid marble precursor. Single drops of fluidwere produced using a syringe and placed onto loosely packed powder beds of hydrophobic powders. Liquid marbles formed from several powder/liquid combinations were dried at several conditions to investigate the drying conditions required for formation of a stable hollow granule. The formation of stable hollow granules was found to depend on drying temperature and binder concentration. ForHPMC and PVP binder, formation of hollowgranule is proportional to binder viscosity and forHPC binder, this relationship is constant. Different combinations of powder and binder at both drying temperatures - 60 °C and 100 °C - had mixed success rates in forming hollow granules, but generally the success rate was improved by using higher drying temperatures, smaller particles or higher viscosity binder fluids.