The present invention relates to compositions comprising at least one (per)fluoropolyether base oil and at least one polymer obtained by the copolymerization of (per)fluoropolyether (PFPE), tetrafluoroethylene (TFE) and at least one non-homopolymerizable olefin.

The present invention relates to compositions comprising at least one (per)fluoropolyether base oil and at least one polymer obtained by the copolymerization of (per)fluoropolyether (PFPE), tetrafluoroethylene (TFE) and at least one non-homopolymerizable olefin.

Provided is a method for producing a fluoropolymer, the method including a polymerizing step of polymerizing tetrafluoroethylene in an aqueous medium in the presence of an initiator, a chain transfer agent, and a surfactant to provide a fluoropolymer containing more than 80 mol % of a polymerized unit based on tetrafluoroethylene, the chain transfer agent including at least one selected from the group consisting of a dithioester compound, a dithiocarbamate compound, a trithiocarbonate compound, and a xanthate compound. Also provided is a fluoropolymer represented by the formula Af-CRP defined in the description.

Provided is a method for producing a fluoropolymer, the method including a polymerizing step of polymerizing tetrafluoroethylene in an aqueous medium in the presence of an initiator, a chain transfer agent, and a surfactant to provide a fluoropolymer containing more than 80 mol % of a polymerized unit based on tetrafluoroethylene, the chain transfer agent including at least one selected from the group consisting of a dithioester compound, a dithiocarbamate compound, a trithiocarbonate compound, and a xanthate compound. Also provided is a fluoropolymer represented by the formula Af-CRP defined in the description.

Provided is a method for producing a fluoropolymer, the method including a polymerizing step of polymerizing tetrafluoroethylene in an aqueous medium in the presence of an initiator, a chain transfer agent, and a surfactant to provide a fluoropolymer containing more than 80 mol % of a polymerized unit based on tetrafluoroethylene, the chain transfer agent including at least one selected from the group consisting of a dithioester compound, a dithiocarbamate compound, a trithiocarbonate compound, and a xanthate compound. Also provided is a fluoropolymer represented by the formula Af-CRP defined in the description.

Provided is a method for producing a fluorine-containing polymer, comprising polymerizing a fluorine-containing monomer in the presence of a fluorine-free compound (1) represented by general formula (1), a polymerization initiator, and an aqueous medium to produce the fluorine-containing polymer:

CX.sup.1X.sup.2═CX.sup.3—R—Z  General formula (1):

wherein X.sup.1, X.sup.2, and X.sup.3 are each independently H or an alkyl group; R is a single bond or an alkylene group; the total number of carbon atoms of X.sup.1, X.sup.2, X.sup.3, and R is 0 to 5; Z is —SO.sub.3M, —OSO.sub.3M, —P(═O)(OM).sub.2, —OP(O)(OM).sub.2, or —B(OM).sub.2; M is H, a metal atom, NR.sup.1.sub.4, optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium; and R.sup.1 is independently H or an organic group, and any two R.sup.1 may be bonded to each other to form a ring.

Provided is a method for producing a fluorine-containing polymer, comprising polymerizing a fluorine-containing monomer in the presence of a fluorine-free compound (1) represented by general formula (1), a polymerization initiator, and an aqueous medium to produce the fluorine-containing polymer:

CX.sup.1X.sup.2═CX.sup.3—R—Z  General formula (1):

wherein X.sup.1, X.sup.2, and X.sup.3 are each independently H or an alkyl group; R is a single bond or an alkylene group; the total number of carbon atoms of X.sup.1, X.sup.2, X.sup.3, and R is 0 to 5; Z is —SO.sub.3M, —OSO.sub.3M, —P(═O)(OM).sub.2, —OP(O)(OM).sub.2, or —B(OM).sub.2; M is H, a metal atom, NR.sup.1.sub.4, optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium; and R.sup.1 is independently H or an organic group, and any two R.sup.1 may be bonded to each other to form a ring.

A protective tarpaulin for a propulsion engine of an aircraft is made of a material having an air permeability index that is sufficiently high to prevent the accumulation of moisture inside the engine or a nacelle surrounding the engine.

A protective tarpaulin for a propulsion engine of an aircraft is made of a material having an air permeability index that is sufficiently high to prevent the accumulation of moisture inside the engine or a nacelle surrounding the engine.

The present disclosure provides elastomer blends comprising mixtures of partially fluorinated elastomers, such as tetrafluoroethylene propylene elastomers (FEPM or TFEP) and fluorocarbon rubbers, such as vinylidene fluoride-based elastomers (FKM or FEP). The elastomer blends can be prepared using two-roll mills, internal mixers, or other mixing technique and can be molded into seals, gaskets, o-rings or other articles using extrusion, injection molding, compression molding or the like. The resultant elastomeric articles can provide good sealing performance, including at moderate or low temperatures, and exhibit good chemical compatibility and resistance when exposed to common wellbore environments. In some cases, the elastomer blends can provide performance characteristics previously only available from perfluorinated elastomers (FFKM), but without requiring the complex processing conditions associated with preparing perfluorinated elastomers.