In a process of (co)polymerization in aqueous emulsion of fluorinated olefinic monomers it is added to the reaction medium a microemulsion of fluoropolyoxyalkylenes having hydrogenated end groups and/or hydrogenated repetitive units. A remarkable reduction in the reaction induction period is so obtained, with formation of a product with improved mechanical properties and higher thermal and chemical resistance.

Co)polymerization process in aqueous emulsion of fluorinated olefinic monomers

New fluoroelastomers are described, comprising monomeric units deriving from a bis-olefin having general formula: wherein: R1, R2, R3, R4, R5, R6, equal or different from each other, are H or alkyls C1-C5; Z is an alkylene or cycloalkylene radical C1-C18, linear or branched, optionally containing oxygen atoms, preferably at least partially fluorinated, or a (per)fluoro-polyoxyalkylene radical. Such products are endowed with improved processability, especially during calendering of the vulcanization mixture, along with superior mechanical and workability properties during extrusion and injection molding, with a very good mold release.

Fluoroelastomers comprising monomeric units deriving from a bis-olefin

1) Fluoroelastomers characterized by the presence of iodine or bromine atoms at the end of the polymeric chain in an amount equal to or lower than 1 iodine or bromine atom per polymeric chain, and by a bromine content in the chain ranging from 0.05 to 2% by weight referred to the total weight of the monomeric units. Said fluoroelastomers exhibit improved characteristics of processability, particularly as regards the utilization in injection molding processes and the detaching from the molds, as well as of stability to heat. 2) A process for preparing fluoroelastomers containing iodine or bromine atoms at the ends of the polymeric chain, in an amount equal to or lower than 1 iodine or bromine atom per polymeric chain, which process comprises polymerizing mixes of fluorinated monomers (VDF, TFE, HFP, FVE) in bulk in suspension, in aqueous emulsion, or in solution of organic solvents by means of radical starters, in the presence of compounds capable of providing T or Br ions in the polymerization medium and conditions.

Fluoroelastomers endowed with improved processability and process for preparing them

A process for fluoropolymer production which is effective in improving the productivity of the emulsion polymerization method while maintaining the excellent material properties of the fluoropolymer, which comprises: (a) a first polymerization step in which a fluoromonomer or a monomer mixture of a fluoromonomer and a nonfluorinated monomer is emulsion-polymerized in the presence of a radical polymerization initiator and an emulsifying agent in an aqueous medium; (b) a dilution step in which the resultant aqueous emulsion of polymer particles is diluted with water to reduce both the number of emulsified polymer particles per unit amount of the aqueous medium and the concentration of the emulsifying agent; and (c) a second polymerization step in which the fluoromonomer and/or nonfluorinated monomer is emulsion-polymerized in the diluted emulsion

Process for producing fluoropolymer

A fluorochemical composition for rendering a fibrous substrate oil and/or water repellent which comprises a solution or dispersion of a fluoropolymer having a partially or fully fluorinated backbone and comprising one or more repeating units corresponding to the general formula (I) wherein Rf represents a perfluorinated organic group having a chain length of at least 2 atoms and having at least one carbon atom and optional auxiliary components.

Polymers containing perfluorovinyl ethers and applications for such polymers

CURABLE MIXES OF FLUOROELASTOMERSCONTAINING BROMINE OR IODINE AND OF ORGANIC PEROXIDES Abstract There are described mixes, which are curable by using radical intermediates, are based on fluoroelastomers containing bromine or iodine, exhibit, during curing, a low emission of toxic vapors of methyl bromide or iodide and are characterized in that they contain, as cross-linking agents, peroxides having the following formulas: (I) (II) wherein the substituents from R1 to R17 have the significan-ces defined in the specification.

Curable mixtures of fluoroelastomers containing bromine or iodine and of organic peroxides

Fluoroelastomeric copolymers exhibiting high resistance to bases and alcohols, as well as high mechanical properties and low-temperature resistance, comprising, in moles: 4-75% of units of vinylidene fluoride; 12-40% of units of hexafluoropropene and/or perfluorovinylether and/or hydropentafluoropropene and/or chlorotrifluoroethylene; 2-35% of units of an olefin containing up to 4 carbon atoms; 2-60% of units of tetrafluoroethylene, provided that, when the sum of the olefin units and the perfluorovinylether units is equal to or greater than 70%, such copolymers possess a molecular weight sufficiently high to exhibit good mechanical characteristics

Fluoroelastomers based on vinylidene fluoride exhibiting superior resistance to organic bases

Fluoroelastomers comprising, by mole: (a) from 33 to 75% of tetrafluoroethylene (TFE); (b) from 15 to 45% of a perfluorovinylether (PVE); (c) from 10 to 22% of vinylidene fluoride (VDF). They are endowed with high resistance to polar solvents and to bases, excellent compression set also at high temperatures, low Tg and good processability. They result particularly suitable for the manufacture of sealing elements (O-rings) for plants intended to the production of methylterbutylether (MTBE).

Fluoroelastomers endowed with high resistance to polar solvents and to bases

Fluoroelastic copolymers, suitable for the manufacture of O-rings, comprising by weight: 48-65% of VDF units 21-36% of HFP units 3-9% of PAVE units 0-17% of TFE units

Vinylidene fluoride based fluoroelastomeric copolymers modified with perfluoroalkylvinylether

Fluoroelastomeric copolymers, vulcanizable by ionic methods, suitable for the manufacture of "shaft seals" and "fuel hoses", comprising by weight:

Anna Minutillo

Papers

Curable mixtures of fluoroelastomers containing bromine or iodine and of organic peroxides

Fluoroelastomers based on vinylidene fluoride exhibiting superior resistance to organic bases

Fluoroelastomers endowed with high resistance to polar solvents and to bases

Vinylidene fluoride based fluoroelastomeric copolymers modified with perfluoroalkylvinylether

Ionically vulcanizable fluoroelastomeric copolymers