New methodologies for separating glass transitions from energy of film formation in polystyrene latexes

Polystyrene latexes were synthesized to study water evaporation details and to separate the energy of film formation from the glass transition temperature. Three experimental techniques were employed in the present work to study the formation of polystyrene latex films: standard differential scanning calorimetry (DSC), modulated DSC, and the Mahr method applied to modulated DSC. High-resolution thermogravimetric analysis (TGA) was used to study the water evaporation. The TGA experiments revealed evaporation curves consistent with the notion of surface tension and tortuosity effects being the controlling factors. The method of Mahr was combined with the new software package for DSC to provide an improved method of separating the glass transition of polystyrene from its surface tension-based free energy of film formation. The result was that the films formed under the extremely mild conditions employed had 30-70% of their surfaces obliterated by interfacial adhesion. (C) 1999 John Wiley & Sons, Inc.