Anomalous bulk diffusion of methylene diphenyl diisocyanate in silicone elastomer

Wortmann M, Viertel K, Welle A, Keil W, Frese N, Hachmann W, Krieger P, Brikmann J, Schmidt C, Moritzer E, Huesgen B (2021)
International Journal of Heat and Mass Transfer 177: 121536.

Zeitschriftenaufsatz | Veröffentlicht | Englisch
 
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Autor*in
Wortmann, Martin; Viertel, Klaus; Welle, Alexander; Keil, Waldemar; Frese, NatalieUniBi; Hachmann, WiebkeUniBi; Krieger, Philipp; Brikmann, Johannes; Schmidt, Claudia; Moritzer, Elmar; Huesgen, Bruno
Abstract / Bemerkung
In this study, we investigate the anomalous diffusion of methylene diphenylmethane-4,4'-diisocyanate (MDI) into fumed silica filled poly(dimethylsiloxane) (PDMS) elastomer, which occurs in the industrial application of polyurethane vacuum casting. The absorbed MDI polymerizes with moisture to polyurea within the silicone medium, forming a sequential semi interpenetrating polymer network. This results in the formation of polyurea clusters near the exposed surface. Here we focus on the spatially resolved chemical characterization on the micrometer scale utilizing time-of-flight secondary ion mass spectrom-etry (ToF-SIMS), transmission electron microscopy (TEM), helium ion microscopy (HIM), atomic force mi-croscopy (AFM), thermo-gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) as well as nuclear magnetic resonance spectroscopy (NMR). The concentration profile was determined experimen-tally using a customized method based on TGA. It was shown that the polyurea reaction of the MDI causes a time-dependency of both the surface concentration and the diffusion coefficient. Six analytical solutions to the diffusion equation obeying different time-dependent boundary conditions with different physical implications are proposed and used to model the measured concentration profiles. The parameterized models showed good predictive power for the measured absorption data and thus substantiated the conjectured molecular phenomena. (C) 2021 Elsevier Ltd. All rights reserved.
Stichworte
Anomalous diffusion; Time-dependent surface concentration; Time-dependent diffusion coefficient; Mathematical modelling vacuum; casting
Erscheinungsjahr
2021
Zeitschriftentitel
International Journal of Heat and Mass Transfer
Band
177
Art.-Nr.
121536
ISSN
0017-9310
eISSN
1879-2189
Page URI
https://pub.uni-bielefeld.de/record/2957056

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Wortmann M, Viertel K, Welle A, et al. Anomalous bulk diffusion of methylene diphenyl diisocyanate in silicone elastomer. International Journal of Heat and Mass Transfer. 2021;177: 121536.
Wortmann, M., Viertel, K., Welle, A., Keil, W., Frese, N., Hachmann, W., Krieger, P., et al. (2021). Anomalous bulk diffusion of methylene diphenyl diisocyanate in silicone elastomer. International Journal of Heat and Mass Transfer, 177, 121536. https://doi.org/10.1016/j.ijheatmasstransfer.2021.121536
Wortmann, M., Viertel, K., Welle, A., Keil, W., Frese, N., Hachmann, W., Krieger, P., Brikmann, J., Schmidt, C., Moritzer, E., et al. (2021). Anomalous bulk diffusion of methylene diphenyl diisocyanate in silicone elastomer. International Journal of Heat and Mass Transfer 177:121536.
Wortmann, M., et al., 2021. Anomalous bulk diffusion of methylene diphenyl diisocyanate in silicone elastomer. International Journal of Heat and Mass Transfer, 177: 121536.
M. Wortmann, et al., “Anomalous bulk diffusion of methylene diphenyl diisocyanate in silicone elastomer”, International Journal of Heat and Mass Transfer, vol. 177, 2021, : 121536.
Wortmann, M., Viertel, K., Welle, A., Keil, W., Frese, N., Hachmann, W., Krieger, P., Brikmann, J., Schmidt, C., Moritzer, E., Huesgen, B.: Anomalous bulk diffusion of methylene diphenyl diisocyanate in silicone elastomer. International Journal of Heat and Mass Transfer. 177, : 121536 (2021).
Wortmann, Martin, Viertel, Klaus, Welle, Alexander, Keil, Waldemar, Frese, Natalie, Hachmann, Wiebke, Krieger, Philipp, Brikmann, Johannes, Schmidt, Claudia, Moritzer, Elmar, and Huesgen, Bruno. “Anomalous bulk diffusion of methylene diphenyl diisocyanate in silicone elastomer”. International Journal of Heat and Mass Transfer 177 (2021): 121536.

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