Key factors in stable formation of liquid marble and hollow granules

Research into formation of hollow granules from liquid marbles is an emerging field in hydrophobic granulation. A liquid marble is formed by a network of self-assembled hydrophobic powder around a droplet, but the driving force for formation has not been properly addressed to date in the literature. This paper will study the effect of impact kinetic energy on liquid marble formation for various fluids and particles. More over, this paper will investigate the required conditions for hollow granule formation during drying by considering different parameters. In this study, single drops of fluid were produced using a syringe and released from different heights onto loosely packed powder bed. The degree of powder coverage after impact was photographed and analyzed using ImageJ software. In another set of experiment, liquid marbles formed from several powder/liquid combinations were placed into an oven to investigate the condition required for formation of a stable hollow granule. The results showed that as kinetic energy is increased, the percentage of coverage of liquid droplet by powder increases. As particle size is increased, the percentage of coverage also increases. The formation of stable hollow granules was found to depend on particle and binder properties, mono-layer or multi-layer coverage of droplet with particles, droplet size, and drying speed which is mostly related to drying temperature.