Effects of Carboxymethyl Cellulose and Ethyl(Hydroxyethyl) Cellulose on Surface Structure of Coatings Drawn Down From Polystyrene Suspensions, 2003 Advanced Coating Fundamentals Symposium Proceedings

The surface structure of coating layers drawn down from polystyrene suspensions was investigated. The effects of two different soluble cellulose ethers, ethyl(hydroxyethyl) cellulose and carboxymethyl cellulose, were compared. Each of the suspensions was investigated at three different concentration levels of the soluble cellulose ethers. An Atomic Force Microscope was used to investigate the surface structure of coating layers drawn down on polyester substrates from aqueous polystyrene (PS) suspensions. The surface structure was interpreted by calculating the pair distribution function ( ) r g , where r is the radius of a ring centered at a particle.

The colloidal stability of the polystyrene suspensions was also investigated by means of rheology. The relative viscosity was calculated in order to elucidate the colloidal stability and degree of flocculation.

Ethyl(hydroxyethyl) cellulose possesses temperature responsive properties, and the suspensions were investigated at two temperatures, 23 o C and 55 o C. The effects of the concentration of cellulose ether on the relative viscosity indicated that ethyl(hydroxyethyl) cellulose, at least at the higher temperature, destabilized the PS suspensions by a capillary induced phase separation mechanism