Abstract: A cross-linked product of ethylene-hexafluoropropylene copolymer is a good elastic material and has excellent resistance to attack by uranium hexafluoride even at a high temperature. Components made of said copolymer exhibit surprisingly long life, when used in a uranium enrichment plant.

Abstract: A process for preparing an aqueous concentrated latex of a copolymer or terpolymer of ethylene and a C.sub.2 -C.sub.3 -perfluorocarbon by creaming a latex of 25-30% copolymer solids and recovering a concentrated latex having 1.5-2.5 times the concentration of the starting latex. The concentrated latex can be used to prepare crack-free or void-free coatings on substrates.

Abstract: Compositions which when coated onto wire as insulation have good resistance to deterioration under low voltage AC stress in hot water are provided which comprise a melt-processible copolymer consisting essentially of units of tetrafluoroethylene and at least one comonomer that is a selected ethylenically unsaturated fluorinated monomer, and an organo-polysiloxane that is substantially stable and nonvolatile at the temperature of melt-processing for the copolymer used, is substantially incompatible with the copolymer, and is dispersed in the copolymer. The compositions are prepared by employing techniques which provide sufficient transporting pressure to transport the components into a mixing zone, and which provide shearing action sufficient to cause the organopolysiloxane to disperse.

Abstract: A fluoroelastomer composition comprising (a) a fluoroelastomer having stabilized end group derived from an isoparaffin selected from the group consisting of isobutane, isopentane and isohexane, (b) at least one member selected from the group consisting of bivalent metal oxides, bivalent metal hydroxides and mixtures of bivalent metal oxide or metal hydroxide with metal salt of weak acid, (c) an aromatic polyhydroxy compound and (d) a quaternary ammonium compound of 8-alkyl- (or 8-aralkyl-)1,8-diazabicyclo[5.4.0]-7-undecenium, provides a fluoro-rubber having low compression set and excellent elastic properties and has excellent processing and storage properties. The fluoroelastomer can be cured with appropriate induction time and fast cure rate by the use of a specific curing agent system mentioned above.

Abstract: A method is provided for isolating an elastomer from a mixture of the elastomer and water containing up to about 90% by weight water by feeding the mixture into a thermally controlled, vertical separator containing a rotating screw, simultaneously feeding excess water under pressure into the separator, withdrawing concentrated elastomer containing less than about 10% by weight total volatiles (including water) from the metering section of the separator and withdrawing feed water and excess water from a water discharge port located near the upper end of the separator.In addition, apparatus for isolating elastomers from mixtures of elastomers and water is provided.

Abstract: An elastomeric fluoropolymer having improved low temperature properties is provided. The composition contains polymerized units of 57-61 weight % vinylidene fluoride, 27-31 weight % hexafluoropropene, and 10-14 weight % tetrafluoroethylene.

Abstract: A process for producing tetrafluoroethylene/hexafluoropropylene copolymer having a hexafluoropropylene content of 8 to 20% by weight and having an excellent stress-cracking resistance and also excellent heat resistance, molding properties, chemical resistance and electrical characteristics, which comprises polymerizing tetrafluoroethylene monomer and hexafluoropropylene monomer in the presence of a polymerization initiator, wherein the tetrafluoroethylene monomer is used in a large amount at the first stage of the polymerization reaction and thereafter the polymerization reaction is continued in a smaller amount of the tetrafluoroethylene monomer.

Abstract: A high molecular weight vinylidene fluoride polymer resin having improved melt flow properties and further characterized as having a bimodal molecular weight distribution, as measured by gel permeation chromatography, and a specified critical shear stress.

Abstract: A tetrafluoroethylene polymer comprising primary particles having core and shell portions, the core portion comprising tetrafluoroethylene polymerized in the presence of a perfluoroalkyl or alkoxy trifluoroethylene comonomer, particularly hexafluoropropylene, and shell portion consisting of tetrafluoroethylene homopolymer, or a copolymer of tetrafluoroethylene in which the comonomer concentration is less than half that in the core portion.

Abstract: A process for preparing new elastomeric copolymers of vinylidene fluoride having exceptionally valuable properties is disclosed. Monomeric mixtures containing vinylidene fluoride in such quantities as to yield elastomeric products are polymerized in solution, emulsion or suspension, or in the absence of solvents and/or dispersants (mass or bulk) in the presence of radical polymerization initiators, at temperatures of -30.degree. C to =200.degree. C, preferably at 0.degree. C to 120.degree. C, and at a pressure of from autonomous pressure to 300 atmospheres. In this process, vinylidene fluoride is fed into the reaction mixture during the polymerization and in a quantity such that the ratio between the added vinylidene fluoride and the vinylidene fluoride of the monomeric mixture subjected to polymerization varies between 0.1 and 1.5.

Abstract: A process for the polymerization of vinylidene fluoride H.sub.2 C=CF.sub.2 using a novel class of fluorinated emulsifiers having the general formula:R.sub.f --C.sub.2 H.sub.4 --SO.sub.3 Mwherein R.sub.f is a perfluorinated radical having 4 to 10 carbon atoms and M is an alkali metal such as lithium, sodium or potassium or an ammonium radical NH.sub.4.

Abstract: Polymers and copolymers of ##STR1## are disclosed, wherein X and X.sup.1 are halogen.

Abstract: It is known to heat treat melt-processible blends of copolymers of tetrafluoroethylene and hexafluoropropylene in the molten state at elevated temperatures for several hours in the presence of an atmosphere containing water vapor in order to remove volatile material from the copolymer and to improve the thermal stability of the copolymer. Such heating results in foaming of the molten copolymer which is undesirable because it slows down the production rate. According to the process of this invention, the production rate can be increased by employing two or more of the copolymers separately in the heat treatment, at least one copolymer having a melt viscosity higher, and at least one copolymer having melt viscosity lower, than the final desired viscosity of the blend, and then blending the copolymers after the heat treatment.

Abstract: A cured fluorinated elastomeric copolymer of vinylidene fluoride and at least one comonomer selected from the group consisting of chlorotrifluoroethylene, perfluoropropene and tetrafluoroethylene, said cured elastomer having a compression set below about 10 percent after 24 hours at 205.degree. C. in ASTM D 395-61 method B and being prepared from a material having a Mooney 10 point rise at 120.degree. C. above 25 minutes using ASTM D 1646-63 method with the small rotor.

Abstract: Finely divided polytetrafluoroethylene molding powder is disclosed having a remarkable combination of high apparent density and high moldability, the latter being reflected as a small difference in specific gravity (.DELTA.SG) of standard moldings molded at high and low preform pressures. For example, molding powders having an average particle diameter (d.sub.50) of no greater than 60, a .DELTA.SG.sub.5.sub.-1 of no greater than 30 and apparent density of at least 600 g/l are disclosed. These molding powders are obtained from unique process steps involving either the fine powder type of polytetrafluoroethylene or the granular type of polytetrafluoroethylene as the starting material. The fine powder type is compacted to a high degree, followed by partially decompacting the resultant compacted fine powder to the molding powder particle size desired.