Film Formation from Concentrated Reactive Silicone Emulsions. 1. Drying Mechanism

Drying mechanisms of concentrated, reactive poly(dimethylsiloxane) in water emulsions, stabilized by a polyethoxylated fatty alcohol, were studied by visual observation, gravimetry, attenuated total reflectance, and infrared microscopy. The effects of some parameters were investigated, namely, thickness of the cast layer, surfactant concentration, and presence of a CaCO 3 filler. The drying process can be described as three successive fronts, parallel to the surface, moving in a vertical direction, from top to bottom. The first front transforms the color of the emulsion from white to transparent, the second is a coalescence front, and the third restores the initial white color. The main effect of all studied parameters is to alter the global drying rate and drying duration. The fate of the surfactant and the structure of the film after drying are examined in parts 2 and 3 of this series, respectively.