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Diffusion Measurements With Fourier Transform Infrared Attenuated Total Reflectance Spectroscopy: Water Diffusion in Polypropylene

Published

Author(s)

X Yi, J J. Pellegrino

Abstract

The diffusion of pure liquid water into a commercial polypropylene (PP) film at 278-348 K was studied with Fourier transform infrared attenuated total reflectance spectroscopy. Abnormal diffusion behavior was indicated by a significant deviation between the experimental data and a Fickian diffusion model with the conventional saturated boundary condition applied at the water/PP interface. This deviation was observed at all the temperatures studied. With a modified boundary condition that took into account a mass-transfer resistance at the water/PP interface, the Fickian model was able to represent the experimental data satisfactorily. The average water diffusion coefficient varied between 1.41 and 7.64 X 10-9 cm2/s, with an activation energy of diffusion of about 19.3 kJ/mol. The interfacial mass-transfer resistance was represented by an exponential model with an empirical relaxation parameter. The relaxation parameter Β increased as the temperature increased and reached an apparent plateau. The infrared spectrum indicated a positive chemical shift of 18 cm-1 for the less strongly hydrogen-bonded component of the broad hydroxyl stretching band with respect to pure liquid water, indicating that hydrogen-bonding interactions were weakened or broken when water molecules diffused into the PP matrix.
Citation
Journal of Polymer Science Part B-Polymer Physics
Volume
40
Issue
No. 10

Keywords

diffusion, FTIR-ATR, polypropylene, surface resistance, water

Citation

Yi, X. and Pellegrino, J. (2002), Diffusion Measurements With Fourier Transform Infrared Attenuated Total Reflectance Spectroscopy: Water Diffusion in Polypropylene, Journal of Polymer Science Part B-Polymer Physics (Accessed April 14, 2024)
Created May 1, 2002, Updated February 17, 2017