Near‐infrared spectroscopy for the quantitative determination of mass transfer and water absorption kinetics by a polymer solution |
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Authors: | Céline Pochat‐Bohatier Warit Werapun Denis Bouyer Watchanida Chinpa André Deratani |
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Institution: | 1. Laboratoire de Génie des Procédés, Eau et Bioproduits, UMR Cirad‐16, Université Montpellier 2, 2 Place Bataillon, 34095 Montpellier cedex 05, France;2. Institut Européen des Membranes, CNRS/ENSCM/UM2 UMR 5635, Université Montpellier 2, 2 Place Bataillon, 34095 Montpellier cedex 05, France |
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Abstract: | This article reports a new method to quantify the water absorption kinetics and the mass transfer in a polymer solution by using near‐infrared (NIR) spectroscopy and partial least‐squares (PLS) models, while it is exposed to a humid atmosphere. Polymer solutions used in this study were made with highly polar solvents exhibiting both a high affinity for water and a low volatility such as dimethylformamide, dimethylacetamide, and N‐methylpyrrolidone. Poly(ethersulfone) and poly(etherimide) were chosen as polymer models as the method could provide useful information for coating process and membrane fabrication monitoring. Whereas gravimetric kinetics yield data on the overall mass transfer, including both water absorption and solvent evaporation, in situ analyses using NIR can quantify separately the solvent and nonsolvent concentration change in the polymer solution. Quantitative models were developed using PLS regression to predict the local water, polymer, and solvent weight fractions in the polymer solution. The method was proved to be suitable for the different studied systems and allowed to infer mass transfers until the onset of the phase separation process. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1960–1969, 2010 |
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Keywords: | kinetics near‐infrared spectroscopy partial least‐squares regression phase separation polymer solution water absorption |
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