Abstract
In this paper we describe the development of a real-time, noninvasive technique using infrared (IR) thermography for measurement of the temperature of polymer solutions cast as thin films in which evaporation of a volatile solvent occurs. The technique requires the accurate determination of a single surface radiation property, the emittance, and its dependence on the casting solution composition. We report results obtained for the cellulose acetate (CA)-acetone system for which IR measurements indicate a relatively rapid and significant temperature decrease followed by a gradual temperature recovery toward the initial temperature. In general the thin film temperature response can be described by the parameters ΔTmax, the maximum degree of cooling; tmin, the time at which Tmin is reached; and the recovery temperature, Trec, at a time equal to 2 × tmin. For 155 and 258 μm thick films evaporatively cast from a 15 wt% CA solution, IR thermography indicated maximum temperature decreases of 18 and 26°C, respectively. The characteristics of the thin film temperature curves for these two cases compare favorably with those predicted by a first-principles model recently developed by the authors. Based upon these results, the general applicability of the infrared technique for the study of dense film- and membrane-formation processes is described, and the significance of thin film temperature measurements with respect to membrane morphology is discussed.
| Original language | English |
|---|---|
| Pages (from-to) | 249-261 |
| Number of pages | 13 |
| Journal | Journal of Membrane Science |
| Volume | 107 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - 30 Nov 1995 |
Funding
The authors gratefully acknowledge the support of the NASA Bioserve Space Technologies Center and the NSF Center for Separations Using Thin Films at the University of Colorado. The authors also acknowledge the following: William Eberly of the Department of Chemistry at the University of Colorado for assistance with the FTIR measurements; Dr. Robert Far-rington of the National Renewable Energy Laboratory, Golden, CO., for the use of their IR camera; and John G. Sanders and John Ziehl of Flir Systems, Inc., in Portland, OR for their assistance in obtaining the response characteristics of the Hughes TVS-4500 thermographic imaging camera. Finally the authors would like to thank the reviewers whose constructive comments helped to improve this paper.
| Funders | Funder number |
|---|---|
| National Science Foundation | |
| National Aeronautics and Space Administration | |
| University of Colorado |
Keywords
- Infrared technique
- Membrane preparation and structure
- Temperature measurement
- Theory