DSC evaluation of binder content in latex paints

Abstract

The estimate by differential scanning calorimetry of the enthalpy of thermal decomposition of the organic fraction in a complex material can be used, in proper conditions, for evaluating the concentration of the organic components. The application of this technique of thermal analysis to latex paints aimed at identification of binder content is discussed in this paper. On the one hand it gives good results on binder content estimate; on the other hand it highlights some aspects of the thermal decomposition of polymers enclosed in an inorganic matrix. The phenomena of thermal decomposition are studied for the main components of latex paints, i.e. for polymers, and for complete paint formulations. The materials considered include widely used binders for the manufacture of latex paints such as vinyl acetate/Versatate copolymers and styrene/acrylic copolymers, rheology modifiers such as cellulose ethers and other standard components of latex paints. Formulations representing typical latex paints with different binder content and simplified polymer/filler systems are considered. Although decomposition paths are very different for different polymers and for the same polymer in different concentrations, the overall heat output is consistent and proportional to the amount of polymer in the sample. Therefore identification by DSC measurements of the binder content in a latex paint appears as a feasible technique.