8 research outputs found
Effect of the acrylic acid content on the permeability and water uptake of latex films
Acrylic acid (AA) is a monomer commonly employed in emulsion polymerization
to provide electrostatic colloidal stability and improve specific film
performance. The addition of AA not only modifies the kinetics of the
polymerization, but also it takes part in the interaction between colloidal
particles, which has a strong influence on their packing and consequent latex
film properties. In this contribution a theoretical modeling of the latex film
formation is presented and compared to experimental results: water vapor
permeability and latex film capacitance are studied as a function of AA
content. It has been shown that water uptake is mainly affected by film
morphology which in turn is defined by intercolloidal interaction and drying
rate.Comment: 16 pages, 7 figure
Lateral surface nonuniformities in drying latex films
The length scales of film, thickness nonuniformities, commonly observed in polymer colloid (i.e., latex) films, are predicted. This prediction is achieved by investigating the stability behavior of drying latex films. A linear stability analysis is performed on a base solution representing a uniformly drying latex film containing a surfactant. The analysis identifies film thickness nonuniformities over two length scales: long (millimeter) range (from lubrication theory) and short (micrometer) range (from nonlubrication theory). Evaporation and surfactant desorption into the bulk film are identified as the primary destabilizing mechanisms during drying. Experimental evidence through direct visualization and atomic force microscopy confirm the existence of nonuniformities over both length scales, which are shown to be functions of parameters such as initial particle volume fraction, surfactant amount, and desorption strength, while being independent of drying rate. © 2008 American Institute of Chemical Engineers