Drying dynamics of polymers films by an interferometric technique |
| |
Authors: | J.A. Olivares,J.M. Galvá n-Miyoshi,F.L.S. Cuppo,F. Zaldo,A. Garcí a-Valenzuela |
| |
Affiliation: | 1. Centro de Investigación en Polímeros, COMEX, Marcos Achar Lobatón 2, 55885 Tepexpan, Estado de México, México;2. Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Apartado Postal 70-186, 04510 México Distrito Federal, México |
| |
Abstract: | We analyze a simple laser reflectivity measurement as a tool to monitor the drying kinetics of transparent polymer films. The reflectivity signal of a laser beam at normal incidence shows oscillations due to interference arising from multiple reflection of the laser light within the drying film. We develop a model to interpret the reflectivity curves in terms of time evolving refractive indices at the top and bottom of the film. We present results of the drying kinetics of transparent alkyd films on a glass substrate of high refractive index. Data shows a clear hallmark indicating the evolution of the crosslinking process. From the reflectivity curves, the time evolution of the refractive indices at the top and bottom is obtained. Assuming a linear-gradient of the refractive index along the depth of the film the average refractive index and consequently the film thickness as a function of time are estimated. Clear features in the time evolution of the refractive indices and thickness, correlate well with qualitative “dust”, “touch” and “fingerprint” drying times. Additionally, we present some preliminary results for water based latex binders, where scattering of light is present, showing that this simple optical technique could be extended for studying latex film formation. |
| |
Keywords: | Film formation Drying time Alkyds Emulsions Optical interference |
本文献已被 ScienceDirect 等数据库收录! |
|