A method for producing a purified fluoropolymer aqueous dispersion, which includes: (A) bringing a fluoropolymer aqueous dispersion obtained using a hydrocarbon surfactant into contact with an anion exchange resin A or a synthetic adsorbent. The anion exchange resin A has an ion-exchange group represented by the following general formula (A1):

—N+R.sup.1R.sup.2R.sup.3X—

wherein each of R1, R2, and R3 are the same or different, and are each a hydrogen atom or an organic group, and at least one of R.sup.1, R.sup.2, and R.sup.3 is an organic group having 3 or more carbon atoms; and X is a counter ion; or an ion-exchange group represented by the following general formula (A2):

—NR.sup.4R.sup.5

wherein each of R.sup.4 and R.sup.5 are the same or different, and are each a hydrogen atom or an organic group, and at least one of R.sup.4 and R.sup.5 is an organic group having 2 or more carbon atoms.

An electrode comprising: NaVOPO.sub.4 having orthorhombic crystalline symmetry and space group Pna2.sub.1, as an active intercalation host material, wherein the electrode is capable of electrochemical insertion and release of greater than one sodium ion per vanadium, wherein the NaVOPO.sub.4 is formed by a solid phase synthesis process from a heated powdered mixture of ammonium metavanadate, ammonium phosphate monobasic, and potassium carbonate, to yield KVOPO.sub.4 having corner-sharing VO.sub.6 octahedra and PO.sub.4 tetrahedra, defining two types of tunnels comprising a first type of tunnel formed of rings of two PO.sub.4 tetrahedra and a second type of tunnel formed of rings of three PO.sub.4 tetrahedra and three VO.sub.6 octahedra, followed by substitution of the potassium ions with sodium ions.

To provide a monomer composition in which the solubility of the polymerization inhibitor in the cyclic monomer is good, the stability of the cyclic monomer during storage is good, and the cyclic monomer and the polymerization inhibitor are easily separated by distillation; and a method for producing a high molecular weight fluorinated polymer from the monomer composition. A monomer composition which comprises a specific cyclic monomer and a polymerization inhibitor, wherein the polymerization inhibitor is a polymerization inhibitor which satisfies (a) it is a 6-membered unsaturated cyclic hydrocarbon having from 1 to 4 substituents, (b) it has, as the substituent, at least one type selected from the group consisting of a t-butyl group, a methyl group, an isopropenyl group, an oxo group and a hydroxy group, (c) in a case where it has an oxo group as one type of the substituent, it has, as the substituent other than the oxo group, either one or both of a t-butyl group and a methyl group, and (d) in a case where it has a hydroxy group as the substituent, the number of the hydroxy group is only one.

A method for producing a fluoropolymer which includes polymerizing a fluoromonomer in an aqueous medium in the presence of a surfactant to provide a fluoropolymer. The surfactant includes at least one selected from the group consisting of a surfactant represented by R.sup.1a—CO—R.sup.2a—CO—R.sup.3a—OSO.sub.3X.sup.a and a surfactant represented by R.sup.1b—CO—(CR.sup.2b.sub.2).sub.n—(OR.sup.3b).sub.p—(CR.sup.4b.sub.2).sub.q-L-OSO.sub.3X.sup.b.

A method for producing a fluoropolymer which includes polymerizing a fluoromonomer in an aqueous medium in the presence of a surfactant to provide a fluoropolymer. The surfactant includes at least one selected from the group consisting of a surfactant represented by R.sup.1a—CO—R.sup.2a—CO—R.sup.3a—OSO.sub.3X.sup.a and a surfactant represented by R.sup.1b—CO—(CR.sup.2b.sub.2).sub.n—(OR.sup.3b).sub.p—(CR.sup.4b.sub.2).sub.q-L-OSO.sub.3X.sup.b.

The present invention relates to a process for the polymerization of fluoromonomers in an aqueous medium, said process comprising the steps of: forming an aqueous emulsion comprising a 2-Alkoxy acetate surfactant and fluoromonomer in a reactor; and initiating polymerization of said fluoromonomer by adding an initiator into the reaction mixture. Preferably, the surfactant used in the instant process is either Sodium 2-[(2-hexyldecyl)oxy] acetate or Sodium-2-dodecyloxyacetate.

The present invention relates to a process for the polymerization of fluoromonomers in an aqueous medium, said process comprising the steps of: forming an aqueous emulsion comprising a 2-Alkoxy acetate surfactant and fluoromonomer in a reactor; and initiating polymerization of said fluoromonomer by adding an initiator into the reaction mixture. Preferably, the surfactant used in the instant process is either Sodium 2-[(2-hexyldecyl)oxy] acetate or Sodium-2-dodecyloxyacetate.

Disclosed is an antioxidant for a polymer electrolyte membrane of a fuel cell including cerium hydrogen phosphate (CeHPO.sub.4). The presence of cerium hydrogen phosphate in the antioxidant enhances the dissolution stability of cerium and improves the ability to capture water, leading to an increase in proton conductivity. In addition, the cerium hydrogen phosphate has a crystal structure composed of smaller cerium particles. This crystal structure greatly improves the ability of the antioxidant to prevent oxidation of the electrolyte membrane. Also disclosed are an electrolyte membrane including the antioxidant, a fuel cell including the electrolyte membrane, a method for preparing the antioxidant, a method for producing the electrolyte membrane, and a method for fabricating the fuel cell.

To provide a PTFE aqueous dispersion which is excellent in mechanical stability, while being not susceptible to foaming. A polytetrafluoroethylene aqueous dispersion which is characterized by containing from 15 to 70 mass % of PTFE particles having an average primary particle diameter of from 0.1 to 0.5 μm; from 0.1 to 20,000 ppm, to the PTFE particles, of a fluorinated emulsifier selected from a C.sub.4-7 fluorinated carboxylic acid which may have an etheric oxygen atom, and salts of thereof; from 1 to 20 parts by mass, to 100 parts by mass of the PTFE particles, of a nonionic surfactant represented by R.sup.1—O-A-H (wherein R.sup.1 is a C.sub.8-18 alkyl group, and A is a polyoxyalkylene chain); from 0.004 to 0.040 parts by mass, to 100 parts by mass of the PTFE particles, of a polyether polysiloxane copolymer, wherein the polyether chain consists solely of a polyoxypropylene group; and water.

The invention includes a method of bonding a perfluoroelastomer material to first surface that includes: (a) contacting a first surface with a bonding agent comprising a curable perfluoropolymer and a curing agent; (b) curing the bonding agent to form a perfluoroelastomer material that is bonded to the first surface. In the practice of such method, the bonding agent may be a solution prepared by dissolving the curable perfluoroelastomer and the curing agent in a solvent. In an embodiment of the invention, the perfluoroelastomer material formed in step (b) is a coating layer or, alternatively, the first surface is a surface of a perfluoroelastomer member and the perfluoroelastomer material formed is a perfluoroelastomer weld.