An experimental test of the scaling prediction for the spatial distribution of water during the drying of colloidal films

• Published in: The European physical journal. ST, Special topics Special topics, 2009, Vol.166 (1), p.21-27
• Main Authors: Ekanayake, P., McDonald, P. J., Keddie, J. L.
• Format: Article
• Language: English
• Subjects: Atomic; Chemistry; Classical and Continuum Physics; Colloidal state and disperse state; Condensed Matter Physics; Exact sciences and technology; General and physical chemistry; Materials Science; Measurement Science and Instrumentation; Molecular; Optical and Plasma Physics; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Physics; Physics and Astronomy; Regular Article; Surface physical chemistry
• ISSN: 1951-6355; 1951-6401
• DOI: 10.1140/epjst/e2009-00872-4

A Peclet number, Pe , for the drying of colloidal films can be used as a predictor of the uniformity of water concentration in the direction normal to the film. Uniform drying is predicted to occur when Pe < 1, whereas with , a layer of packed particles is expected to develop above a more dilute layer. Routh and Zimmerman have more recently proposed that the particle concentration gradient between the packed and dilute layers, , will scale as . Here, this scaling relation is tested experimentally with magnetic resonance profiling data obtained from waterborne colloidal films dried under conditions to yield a range of Pe . It is found that increases with Pe but scales as . This disagreement with the prediction can be attributed to an underestimate of Pe when there are greater non-uniformities of drying, because of an unquantified slowing down of the evaporation rate.