Fluoropolyether elastomer compositions having low glass transition temperatures
A curable composition is provided. The curable composition has at least one functionalized fluoropolyether and at least one radical curing system. Further provided are fluoroelastomer compositions having a glass transition temperature of less than −40° C. and shaped articles comprising fluoroelastomers having glass transition temperatures of less than −40° C. obtained by curing the curable compositions. Also described are methods of making fluoroelastomer compositions having glass transition temperatures of less than −40° C.
1. A curable composition comprising
a) at least one functionalized fluoropolyether having a molecular weight from about 400 g/mole and up to about 25,000 g/mole represented by the formula:
XCF 2 O(CF 2 O) w (C 2 F 4 O) x (C 3 F 6 O) z CF 2 Y
wherein each of X and Y independently from each other is selected from a nitrile group or an alkylene nitrile group, wherein the alkylene nitrile group has an alkylene group containing from 1 to 10 carbon atoms;
wherein w, x, y and z are each independently from each other selected from an integer of from 0 to 30, with the proviso that w+x+y+z is at least 6;
b) a radical curing system comprising at least one radical generating compound;
c) further comprising at least one filler selected from silica containing material, and a carbon containing material or a combination thereof, the carbon containing material being selected from mesoporous carbon nanopowder, carbon nanotubes, carbon black, and modified graphite;
wherein the curable composition comprises at least 30% by weight based on the total amount of the curable composition of the functionalized fluoropolyethers.
2. The curable composition of claim 1 wherein the radical curing system furthermore comprises at least one coagent.
3. The curable composition of claim 1 which cures in a radical curing reaction to produce a composition furthermore comprising a fluorinated elastomer having a glass transition temperature of less than −40° C.
4. The curable composition according to claim 2 wherein the co-agent is selected from polyvinyl or polyallyl-containing compounds.
5. The curable composition according to claim 1 wherein the radical generating compound is a peroxide.
6. The curable composition according to claim 1 comprising at least 40% by weight based on the total amount of the composition of the functionalized fluoropolyether.
7. The curable composition according to claim 6 comprising at least 40% by weight based on the total amount of the curable composition of the functionalized fluoropolyether, and furthermore comprises at least one fluoropolymer having a glass transition temperature of less than 25° C. and that is curable in a radical curing reaction and has a molecular weight that is greater than that of the functionalized fluoropolyether.
8. A composition comprising a cured fluoroelastomer obtained by curing the curable composition of claim 1 .
9. A method of making a composition comprising a fluoroelastomer having a glass transition temperature of less than −40° C., said method comprising
i. providing a curable composition according to claim 1 and
ii. subjecting the curable composition to a radical curing reaction.
10. A shaped article obtained by injection or compression molding the curable composition of claim 1 .