On some aspects of latex drying – ESEM observations

Environmental scanning electron microscopy has been employed to study the drying behaviour of a non-film forming polymethyl methacrylate (PMMA) based latex system. The approach adopted for this study differs slightly when compared to those used previously. Here, by allowing the latex to initially film form, it has been possible to make observations and conclusions regarding the structural development of the specimens under investigation not only in 2D, but also in 3D. The results clearly demonstrate that upon drying, particle packing can yield hexagonal close packed (HCP), square close packed (SCP) and random arrangements, including voids and surface defects that result in the formation of a crystal-like structure. Based on the experimental observations some modifications to the latter stages of the film formation mechanism taking place at temperatures (T) lower than the system glass transition temperature (T_g) have been proposed.