Analytical Series – Rheological and Thermal Characterization of Polymer Coatings – A Case Study

By Or. Menas S. Vratsanos

Polymer coatings are applied to a substrate to impart or improve a particular property or functionality. Among others, the properties that can be enhanced through the use of coatings are aesthetic, mechanical, protective, anticorrosive,¹conductive,² and biomedi­cal³ in nature. Polymer-based dispersions or solutions use water or organic solvent(s) as the vehicle for apply­ing the coating to the substrate,where the use of sol­vent often helps improve the film formation process. For these coatings to be successful, transfor­mation of the initially liquid material to a solid, film-formed state of given properties is essential.

Although extensive analytical tests or techniques are available for characterizing the liquid coating and the final solid film, less characterization effort is devoted to measuring the properties during the coating drying or curing process. The reason for this may be that film formation involves a change of physical state, loss of material, and property changes that vary by many orders of magnitude so that finding an experimental apparatus and geometry can be challenging.

Despite the difficulties, characterization of the transformation from the liquid to solid state is critical to understanding the resulting coating properties. As a result, these data are necessary to properly specify a material for a given application, as well as for designing next-generation coatings that address the limitations of current materials.