Effect of Physical Properties on Microexplosion Occurrence in Water-in-Oil Emulsion Droplets

To investigate the effects of emulsifier type and content on a microexplosion occurrence, we measured the viscosity, diameters of dispersed water droplets, and interfacial tension between water and oil phases in n-hexadecane emulsions prepared under varying emulsifying conditions, as well as microexplosion behavior and emulsion-droplet temperature during heating in an electrical furnace. With increasing emulsifier content, the viscosity of the oil phase remains almost constant, while that of the emulsion increases. Interfacial tension between the water and n-hexadecane phases varies with the emulsifier type but not with the emulsifier content above the saturation adsorption of the emulsifier. Interfacial tension depends very little upon droplet diameter, regardless of emulsifier conditions. Microexplosion temperature and waiting time are affected by emulsifier type, which probably arises from the thermal decomposition of the emulsifiers. In addition, increasing the emulsifier content has a negative influence on microexplosion occurrence, which might also be related to thermal decomposition of the emulsifiers.