The phase behavior, drying kinetics and film-formation of an aluminium chlorohydrate (ACH), glycerol and water combination will be examined in the November 2016 issue of the Journal of Colloid and Interface Science. As described in the advanced publication, posted online on July 27, 2016, researchers from Imperial College London used viscometric, X-ray diffraction, calorimetric, dynamic vapor sorption, spectroscopic, gravimetric and adhesion measurements and test methods to study the roles of humectant concentration, temperature and relative humidity (RH) in film formation.
The phase behavior, drying kinetics and film formation of the ACH (and) glycerol (and) water (aqua) blend were found to exhibit a non-monotonic dependence on the glycerol composition. Films of the ACH blend having no or low glycerol content formed a "skin" upon drying, rendering them transiently "tack-free" regardless of the water content. Furthermore, this phenomenon was temperature-dependent.
According to the researchers, the addition of small glycerol quantities imparted an anti-plasticizing effect, in turn enhancing the drying of the final film. The researchers suspect that competitive binding for ACH sites between water and glycerol at a low RH likely explains this behavior. For more on this study, read the original online feature.