Provided is a method for producing an aqueous dispersion of a fluorine-containing elastomer, comprising polymerizing a fluorine-containing monomer in the presence of a compound (1) having a triple bond and a hydrophilic group and an aqueous medium to produce an aqueous dispersion of a fluorine-containing elastomer.

Described herein is a millable fluorinated block copolymer having (a) at least one A block, wherein the A block is a semi-crystalline segment comprising repeating divalent monomeric units derived from at least TFE, HFP and VDF; (b) at least one B block, wherein the B block is a segment comprising repeating divalent monomeric units derived from at least HFP and VDF; and (c) a bisolefin monomer, wherein at least (i) the semi-crystalline segment of the A block comprises repeating divalent monomeric units derived from TFE, HFP, VDF, and the bisolefin monomer, (ii) the segment of the B block comprises repeating divalent monomeric units derived from HFP, VDF, and the bisolefin monomer, or (iii) a combination thereof; and wherein the millable fluorinated block copolymer has a modulus of 0.1 to 2.5 MPa at 100° C.

Described herein is a millable fluorinated block copolymer having (a) at least one A block, wherein the A block is a semi-crystalline segment comprising repeating divalent monomeric units derived from at least TFE, HFP and VDF; (b) at least one B block, wherein the B block is a segment comprising repeating divalent monomeric units derived from at least HFP and VDF; and (c) a bisolefin monomer, wherein at least (i) the semi-crystalline segment of the A block comprises repeating divalent monomeric units derived from TFE, HFP, VDF, and the bisolefin monomer, (ii) the segment of the B block comprises repeating divalent monomeric units derived from HFP, VDF, and the bisolefin monomer, or (iii) a combination thereof; and wherein the millable fluorinated block copolymer has a modulus of 0.1 to 2.5 MPa at 100° C.

Tetrafluoroethene-based fluoropolymers of low gel content, methods of making the fluoropolymers, methods of extruding the fluoropolymers into articles, and extruded articles comprising the fluoropolymers.

Tetrafluoroethene-based fluoropolymers of low gel content, methods of making the fluoropolymers, methods of extruding the fluoropolymers into articles, and extruded articles comprising the fluoropolymers.

The present invention relates to a halogen-free epoxy resin composition, a prepreg and a laminate containing the same. The halogen-free epoxy resin composition comprises 60 parts by weight of epoxy resin, from 15 to 28 parts by weight of benzoxazine resin, and from 10 to 20 parts by weight of styrene-maleic anhydride. The present invention discloses using from 15 to 28 parts by weight of benzoxazine resin and from 10 to 20 parts by weight of styrene-maleic anhydride to cure 60 parts by weight of epoxy resin, to ensure the Df stability of prepregs at different curing temperature conditions while maintaining low dielectric constant and low dielectric loss. The prepregs and laminates prepared from the resin composition have comprehensive performances, such as low dielectric constant, low dielectric loss, excellent flame retardancy, heat resistance, cohesiveness, low water absorption and moisture resistance, and are suitable for use in halogen-free multilayer circuit boards.

A method of preparing a fluoroelastomer capable of being vulcanized by using peroxide, the method comprising: in the presence of an initiator and a chain transfer agent, conducting emulsion polymerization reaction on comonomers to obtain a fluoroelastomer. The preparation method utilizes alkyl iodide RI.sub.x as the chain transfer agent, and introduces the atom I into the molecular structure of the polymer during the reaction, the atom I acting as a crosslinking point during peroxide vulcanization. The fluoroelastomer obtained via the preparation method greatly improves the performance after being vulcanized; in addition, due to the low cost and extensive sources of alkyl iodide, the preparation method also simplifies the manufacturing process, reduces cost, and has wide application prospects.

A method of preparing a fluoroelastomer capable of being vulcanized by using peroxide, the method comprising: in the presence of an initiator and a chain transfer agent, conducting emulsion polymerization reaction on comonomers to obtain a fluoroelastomer. The preparation method utilizes alkyl iodide RI.sub.x as the chain transfer agent, and introduces the atom I into the molecular structure of the polymer during the reaction, the atom I acting as a crosslinking point during peroxide vulcanization. The fluoroelastomer obtained via the preparation method greatly improves the performance after being vulcanized; in addition, due to the low cost and extensive sources of alkyl iodide, the preparation method also simplifies the manufacturing process, reduces cost, and has wide application prospects.

A method of preparing a fluoroelastomer capable of being vulcanized by using peroxide, the method comprising: in the presence of an initiator and a chain transfer agent, conducting emulsion polymerization reaction on comonomers to obtain a fluoroelastomer. The preparation method utilizes alkyl iodide RI.sub.x as the chain transfer agent, and introduces the atom I into the molecular structure of the polymer during the reaction, the atom I acting as a crosslinking point during peroxide vulcanization. The fluoroelastomer obtained via the preparation method greatly improves the performance after being vulcanized; in addition, due to the low cost and extensive sources of alkyl iodide, the preparation method also simplifies the manufacturing process, reduces cost, and has wide application prospects.

A member to be compressed for an electrochemical device obtained by crosslinking a crosslinkable composition containing a fluorine-containing elastomer containing a unit based on at least one crosslinkable group-containing monomer selected from the group consisting of a crosslinkable group-containing monomer (1) represented by the general formula (1):

CX.sup.1.sub.2═CF—Rf.sup.1—X.sup.2

wherein each X.sup.1 independently represents H or F, and Rf.sup.1 represents a fluorinated alkylene group or a fluorinated oxyalkylene group, and X.sup.2 represents I or Br; and a crosslinkable group-containing monomer (2) represented by the general formula (2):

CX.sup.3.sub.2═CX.sup.3—Z.sup.1—CX.sup.3═CX.sup.3.sub.2

wherein each X.sup.3 independently represents H, F, an alkyl group or a fluorinated alkyl group, and Z.sup.1 represents an alkylene group, a fluorinated alkylene group, a cycloalkylene group, a fluorinated cycloalkylene group, an oxyalkylene group or a fluorinated oxyalkylene group.