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Title: Synthesis and reactions of Viton® model compounds
Author: Lancashire, Marcus John
ISNI:       0000 0004 8501 6238
Awarding Body: Durham University
Current Institution: Durham University
Date of Award: 2019
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Viton® gaskets and O-ring seals are common components of engines and other industrial systems due to their high thermal and chemical resistances. However, degradation of Viton® seals has been observed when they are exposed to oils containing basic or nucleophilic petroleum additives. These processes are difficult to follow by standard analytical techniques due to Viton® being a high molecular weight polymer. In this project, a series of compounds that model the structural features of Viton® elastomers were synthesised by reaction of perfluoroalkyl iodides with vinylidene fluoride and subsequent capping with antimony pentafluoride. These Viton® model compounds were subsequently reacted with a range of bases and nucleophiles and the products characterised by NMR spectroscopy and mass spectrometry. The analysis confirmed that exposure of vinylidene fluoride (VDF) containing Viton® model compounds to basic species (pKa > 10) under relatively mild conditions (temperature ≤ 120 ⁰C, atmospheric pressure) causes dehydrofluorination, synthesising alkenes that can subsequently react with certain nucleophiles such as KOMe and water. These results indicate that Viton® elastomers are vulnerable to dehydrofluorination on exposure to basic petroleum additives, and to subsequent nucleophilic attack that can lead to unwanted crosslinking of the polymer chains and degradation of seals.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available