Fluoroelastomers are widely used in the industry because they retain their elastomeric properties over a wide temperature range and have high resistance to heat, chemicals and fuels. For example, fluoroelastomers are used in the automotive or aircraft industry where resistance to fuel is desired. They also find application in chemical processing and in oil and gas applications. In many applications, it is desirable that the fluoroelastomers remain their elastomeric properties at very low temperatures. In some applications materials have to exposed to temperatures below −40° C. or even below −100° C. for an extended period of time.
Fluoroelastomers of high chemical and temperature resistance and good mechanical properties may be prepared by curing a system comprising copolymers of vinylidene fluoride and/or tetrafluoroethylene with perfluorovinyl ethers and cure site monomers as described for example in European Patent Number 1 829 905 B1. Materials having a glass transition temperatures of about −30° C. are described in EP 1 829 905. However, perfluorovinyl ether monomers are rather expensive materials.
A different approach is described in U.S. Pat. No. 6,160,051. Fluoroelastomers with low glass transition temperatures (TR-10 temperatures in the range of as low as −40° C.) were obtained by copolymerizing vinylidenefluoride in the presence of another fluorinated monomers, cure-site monomers and further in the presence of a diiodoperfluoropolyether to form a block-copolymer. The resulting block-copolymer was cured to provide a low temperature fluoroelastomer.