Stabilization of paraffin emulsions used in the manufacture of chipboard panels by liquid crystalline phases

摘要

Paraffin emulsions are commonly used in the manufacture of chipboard panels to provide resistance to water and humidity. The quality and performance of chipboards are improved with the use of paraffin emulsions stabilized by mixed surfactant systems, although little is known about the basic colloidal chemistry of such systems and their implications in the manufacturing and processing of the chipboard panels. In the present work, the stability and the phase behavior of paraffin emulsions stabilized by a mixture of anionic and nonionic surfactants, are described. Stability is studied by applying thermal and ultracentrifugation cycles, and also by rheology (steady state and dynamic determinations). A significant increase of stability is observed at high [anionic surfactant/(anionic surfactant + nonionic surfactant)] ratios. Phase behavior studies have demonstrated the presence of hexagonal liquid crystalline structures at high ionic surfactantonionic surfactant ratios and the presence of lamellar structures at low ratios. The stability of emulsions could be related to phase behavior, and, thus, providing a qualitative tool to predict stability.