Vinylidene fluoride vulcanization

Fluoroelastomers are copolymers containing fluorine in their structure. There are different kinds of fluoroelastomers depending on the chemical composition and on the production in which the comonomers are found in the chain. As examples of comonomers, we can mention vinylidene fluor-ide-hexafluoropropylene and vinylidene fluoride-chlorotrifluoroethylene. The vulcanization process is performed using peroxides, diamines, and bisphenol. 

E iles with vinylidene fluoride (VFz) copolymers in solution and have determined some reactivity principles which can be used to interpret the vulcanization behavior of related fluoco-elastomers. 

Synonyms (6-Aminohexyl) carbamic acid Carbamic acid, (6-ami nohexyl )-Empiricai C7H16N2O2 Properties M.w. 160.20 Uses Crosslinking agent in vulcanization of vi nyl i dene f I uori de/hexaf I uoropropy lene copolymer and vinylidene fluoride/hexafluoropropylene/tetrafluoroethyle ne copolymers for food-contact articles for repeated use... 

After vulcanization with BPO in the presence of ZnO, amines, or diisocyanates, copolymers of vinylidene fluoride with hexafluoropropylene (70 30) or trifluorochloroethylene (70 30 and 50 50) give oil-resistant, chemically inert elastomers which can be used at temperatures up to 150-200°C. However, these elastomers can be used down to temperatures of only — 10 to — 50°C. 

Most of the other fluorine-containing monomers such as trifluoroethylene, hexafluoropropylene, and pentafluoropropylene are used only for copolymerization with vinyl fluoride, vinylidene fluoride, and tetrafluoroethylene [506,521,535,559-562]. Those copolymers, after a convenient vulcanization procedure using peroxides, diisocyanates, or amines, can be applied as fluorocarbon elastomers [564]. Due to the fluorine content, they have high chemical resistance and often a broad temperature range for application [612]. Polymers of interest are the vinylidenefluoride/hexafluoropropylene copolymer and the... 

Vulcanized vinylidene fluoride-hexafluoropropylene copolymers show excellent resistance to oils and fuels, both at room temperature and at elevated temperature. Vulcanizates also have good resistance to most solvents, although polar solvents such as esters and ketones cause high swelling. 

Vinylidene fluoride-chlorotrifluoroethylene copolymers may be vulcanized by methods similar to those described in the previous section for the vulcanization of vinylidene fluoride-hexafluoropropylene copolymers. The chemistry of the reactions which occur has not been investigated so fully but it is likely that a similar three-stage process is involved. In the first stage, hydrogen chloride rather than hydrogen fluoride is eliminated ... 

Vulcanized vinylidene fluoride-chlorotrifluoroethylene copolymers also have good thermal stability, withstanding prolonged heating at 200°C without... 

The elastomers based on vinylidene fluoride are saturated and cannot be vulcanized with sulphur. As with other saturated rubbers cross-linking can be brought about by irradiation and by the use of peroxides but the only agents of commercial importance until the 1970s were diamines and certain of their derivatives. Of particular importance have been the amine carbamates which are somewhat less reactive and less likely to scorch (premature vulcanization) during processing. Typical materials of this class are ethylene diamine carbamate (IX), hexamethylene diamine carbamate (X) and N,N -dicinnamylidene-1,6-hexane diamine (XI) ... 

Vulcanized vinylidene fluoride-chlorotrifluoroethylene copolymers also have good thermal stability, withstanding prolonged heating at 200°C without serious deterioration. Low temperature performance is limited the glass transition temperatures of copolymers with 50 and 70 mole % vinylidene fluoride are 0°C and — 15°C respectively. The principal application of the elastomers is for components of systems handling strong mineral acids. 

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