E.i. Dupont De Nemours and Company

Dana P Carlson

Thomas Joseph Leck

Walter Werner Schmiegel

Dewey Lynn Kerbow

Allan Harold Olson

Akira Nagasawa

The subject invention relates to segmented fluoropolymers of the A-B-A type where A is a crystallizable fluoropolymer segment, and B is a base-resistant elastomeric fluoropolymer segment, the segmented fluoropolymers being useful as thermoplastic fluoroelastomers which are highly resistant to attack by bases. The fluoroelastomers are useful, for example, in O-rings and shaft seals in internal combustion engines using aggressive oils and in oil well applications.

Fluorinated thermoplastic elastomers with improved base stability

Fluoroelastomer compositions with terminal iodo groups and having improved low temperature properties in the cured state.

Cured fluoroelastomer compositions

Base-resistant peroxide-curable fluoroelastomers with improved processibility comprising a polymeric chain having tetrafluroethylene as one comonomer copolymerized with monomer units selected from the group (a) propylene, (b) propylene and vinylidene fluoride and (c) a C.sub.2-3 hydrocarbon olefin and one or more perfluoro(alkyl vinyl ethers); said polymer chains having terminal iodo-groups.

Base resistant fluoroelastomers with improved processibility and

Base-resistant peroxide-curable fluoroelastomers with improved processibility comprising a polymeric chain having tetrafluoroethylene as one comonomer copolymerized with monomer units selected from the group (a) propylene, (b) propylene and vinylidene fluoride and (c) a C.sub.2-3 hydrocarbon olefin and one or more perfluoro(alkyl vinyl ethers); said polymer chains having terminal iodo-groups.

A composition that exhibits low tendency to foul mold cavities comprising a fluoroelastomer of vinylidene fluoride units and units of at least one other fluorine-containing monomer copolymerizable with vinylidene fluoride; a bisphenol or a polyhydroxy phenol crosslinking agent of the formula ##STR1## where R is H, alkyl or aryl and R' is alkyl or aryl; a divalent metal oxide or hydroxide; and 0.2-4 parts by weight per 100 parts by weight fluoroelastomer of a crosslinking accelerator which is a quaternary ammonium salt of the formula R'.sub.4 N.sup.+ X.sup.- wherein each R' is independently an alkyl group of 2-10 carbon atoms or an aralkyl group of 7-10 carbon atoms and X.sup.- is selected from the group consisting of fluoride, dihydrogen phosphate, periodate, acetate, hydrogen sulfate, methane sulfonate, toluene sulfonate, or an anion of a bisphenol or a polyhydroxy phenol.

Fluoroelastomer composition with low tendency to foul molds

A tetrafluoroethylene-perfluoro(alkyl vinyl ether copolymer in which heat unstable carbinol end-groups (--CH.sub.2 OH groups) present have been protected against heat degradation by treating the copolymer with NH.sub.3 or NH.sub.3 producing compounds.

Heat stable tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymers

Process for crosslinking fluorocarbon polymers, of ethylene and tetrafluoroethylene or chlorotrifluoroethylene, which contain esterified pendant polyfluorinated tertiary alcohol groups.

Crosslinking of esterified fluorocarbon polymer

Terpolymers of tetrafluoroethylene, hexafluoropropylene and either perfluoro(propyl vinyl ether) or perfluoro(ethyl vinyl ether) are described which are prepared by polymerizing the monomers in the presence of a chlorofluoroalkane or chlorofluorohydroalkane solvent and a chain transfer agent and an initiator in either an aqueous or nonaqueous medium. The terpolymers are useful as films, fibers or tubes.

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Chadds Ford, PA, United States of America

Dana P Carlson