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Development of a differential photoacoustic system for the determination of the effective water diffusion and water vapor permeability coefficients in thin films.
- Source :
- Journal of Applied Physics; 9/21/2022, Vol. 132 Issue 11, p1-9, 9p
- Publication Year :
- 2022
-
Abstract
- This paper focused on developing a methodology and metrology using a differential photoacoustic (PA) system to determine the effective water vapor diffusion coefficient (D e f f ) and the effective permeability coefficient (Π) in thin films as a piece of paper and standard polystyrene for a controlled relative humidity. The methodology proposes a new differential photoacoustic system, including the water reservoir, relative humidity, and temperature detectors. Two cells, reference/sample, were used to obtain the instrumental function to reduce the electronic and environmental noises. A method based on the study of ln [ 1 − (S − S 0) / Δ S ] = t / τ D and the behaviors of R<superscript>2</superscript> as a function of the number of data was proposed to assess the region in which the photoacoustic signal should be processed to determine each effective coefficient. S is the amplitude of the PA signal, S 0 is the initial amplitude value, Δ S is the change, t (time), and τ D is the water vapor diffusion time. The effective water diffusion coefficient (D e f f ) for water and polystyrene was 1.90 × 10<superscript>−11</superscript> m<superscript>2</superscript>/s and 3.09 × 10<superscript>−11</superscript> m<superscript>2</superscript>/s, respectively. The permeability coefficient value for the piece of paper was 4.18 × 10<superscript>−9</superscript> mol kg<superscript>−1</superscript> cm<superscript>−2</superscript> s<superscript>−1</superscript> Pa<superscript>−1</superscript>, while for polystyrene, it was 6.80 × 10<superscript>−9</superscript> mol kg<superscript>−1</superscript> cm<superscript>−2</superscript> s<superscript>−1</superscript> Pa<superscript>−1</superscript> for 70% of relative humidity. This methodology can be extended by changing the moisture content on the chamber to obtain the dependence of D e f f as a function of relative humidity. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00218979
- Volume :
- 132
- Issue :
- 11
- Database :
- Complementary Index
- Journal :
- Journal of Applied Physics
- Publication Type :
- Academic Journal
- Accession number :
- 159237935
- Full Text :
- https://doi.org/10.1063/5.0088319