Chemical degradation of fluoroelastomer in an alkaline environment

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Chemical degradation of fluoroelastomer in an alkaline environment

Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/214395

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Title: Chemical degradation of fluoroelastomer in an alkaline environment
Author(s): Mitra, Susanta; Ghanbari-Siahkali, Afshin; Kingshott, Peter; Almdal, Kristoffer; Rehmeier, Helle Kem; Christensen, Anders G.
Abstract: We have investigated the time-dependent chemical degradation of a fluoroelastomer, FKM (Viton® A), in an alkaline environment (10% NaOH, 80 °C). Optical microscopy and SEM analysis reveal that degradation starts with surface roughness right from the earliest stage of exposure (e.g., 1 week) and finally results in cracks on the surface after prolonged exposure. Initially the extent of degradation is mainly confined to the surface regions (a few nanometers) but with longer exposure (e.g., 12 weeks) it extends to below the subsurface region of the fluoroelastomer. The extent of this surface degradation is found to be strong enough to affect the bulk mechanical properties. The molecular mechanisms of the surface chemical degradation were determined using surface analysis (XPS and ATR-FTIR) where the initial degradation was found to proceed via dehydrofluorination. This leads to double bond formation on the rubber backbone which accelerates the degradation even further with longer exposure. Furthermore, the cross-link sites of the exposed rubber samples are also found to be vulnerable to hydrolytic attack under the studied chemical environment as evidenced by the decrease in cross-link density and gel fraction (%).
Publication type: Journal article
Source: Polymer Degradation and Stability, Vol. 83, no. 2 (Feb 2004), pp. 195-206
Publication year: 2004
FOR Code(s): 0303 Macromolecular and Materials Chemistry; 0904 Chemical Engineering; 0912 Materials Engineering
Keyword(s): Caustic soda; Chemical degradation; Crosslinking; Degradation; Dehydrofluorination; Elastomers; FKM (Viton A); Fluoroelastomer; Fourier transform infrared spectroscopy; Mechanical properties; Nucleophilic attack; Optical microscopy; Rubber; Scanning electron microscopy; Seals; Submersible pumps; Surface roughness; Tensile testing; Thermogravimetric analysis; Viscosity; X ray photoelectron spectroscopy; XPS and ATR-FTIR
Publisher: Elsevier
ISSN: 0141-3910
Publisher URL: http://dx.doi.org/10.1016/s0141-3910(03)00235-0
Peer reviewed