Dielectric and thermal analysis of the film formation of a polymer latex

The real-time kinetics of film formation of a floor polish polymer latex coating has been investigated using dielectric measurements of the ionic conductance. Varying levels of ambient humidity were applied and had a dramatic effect on the drying rate, drying mechanism, and final film thermal and mechanical properties. At humidities below 30%, the drying curves followed a power law time decay with two distinguishable regions. The first region showed a drying rate dependence on the order of t(-10), while the second region showed a slower drying rate with a time dependence on the order of t(-2). At higher humidities, the curves become more complex. At the highest humidities, film cracking was observed. Besides dielectric analysis, thermal analysis experiments were conducted that indicated film formation continues over very long times (months). The data also indicate that considerable residual stress remains in the dried films even after these long times.