摘要:
If the employment of polymerization auxiliaries in ammonium form is avoided in the preparation of a polytetrafluoroethylene having a content of 0.02 to 1% by weight of units of a perfluoro-(alkyl vinyl) ether by the suspension process, a polymer which does not tend to discoloration on heating is obtained.
摘要:
Provided are curable fluoroelastomers. Further provided are methods of making the curable elastomers, curable fluoroelastomer compositions and methods of making them and shaped articles made from the curable fluoroelastomer compositions.
摘要:
The invention relates to a curable dental composition comprising a) a curable organopolysiloxane polymer, b) a crosslinker compound capable of crosslinking said organopolysiloxane polymer, c) a catalyst capable of catalyzing a crosslinking reaction of component (A) and component (B), d) a surfactant, e) a F-containing compound, wherein the F-containing compound has the following formula: (G1-L1-O)s-Rfa-O-L2-G2 wherein: G1 and G2 each independently represents a non-ionic endgroup that is free of polyoxyalkylene groups or contains polyoxyalkylene such that the total amount thereof in the F-containing compound is not more than 10% by weight based on the molecular weight of the F-containing compound; L1 and L2 each independently represents an aliphatic hydrocarbon group or a partially or fully fluorinated aliphatic hydrocarbon group; Rfa represents a mono-valent or divalent partially or fully fluorinated aliphatic group or a partially or fully fluorinated aliphatic group interrupted by one or more oxygen atoms; with the proviso that at least one of the following conditions is fulfilled: (i) at least one of the moieties L1-G1 and L2-G2 is partially or fully fluorinated or (ii) Rf is a partially or fully fluorinated aliphatic group interrupted by one or more oxygen atoms. The invention also relates to a kit of parts and a method of producing a dental composition as well as the use of the dental composition for the preparation of or as impression material or for the preparation of crowns and bridges.
摘要:
Use of non-water-soluble organic fluorinated compounds, which are gaseous under the polymerization conditions and act as chain transfer agent in the gas phase, as explosion suppressors in the emulsion polymerization of tetrafluoroethylene.
摘要:
A method for polymerizing, in an aqueous medium, at least one fluorinated monomer in the presence of a non-copolymerizable, non-fluorinated surfactant. The surfactant is generally selected from a non-ionic surfactant, a primary anionic surfactant, or a combination thereof. Fluorinated surfactants are not utilized. The resulting partially fluorinated polymer in the aqueous medium is either a semi-crystalline polymer or a crystalline polymer.
摘要:
Provided is a process for making a copolymer of fluorinated olefin and hydrocarbon olefin selected from ethylene, propylene and mixtures thereof, the process comprising a substantially emulsifier free aqueous emulsion polymerization of said fluorinated olefin and said hydrocarbon olefin, optionally in the presence of fluoropolymer particles and/or fluorinated liquid in a form suitable to improve the copolymerization of fluorinated olefin and hydrocarbon olefin.
摘要:
The present invention provides a method of making an aqueous dispersion of non-melt processible polytetrafluoroethylene, the method comprising:(a) an aqueous emulsion polymerization of an amount of tetrafluoroethylene to produce a final amount of polytetrafluoroethylene solids and optionally up to 1% by weight based on the amount of tetrafluoroethylene of a perfluorinated comonomer, wherein said aqueous emulsion polymerization is initiated with a free radical initiator and the polymerization is carried out in the presence of a fluorinated surfactant, and wherein before completing the feeding of said amount of tetrafluoroethylene but after feeding at least 80% by weight of said amount of tetrafluoroethylene, free radicals capable of introducing ionic end groups or precursors thereof in the polytetrafluoroethylene polymer are caused to be formed at a rate that without counter measures would cause an increase in the polymerization rate of at least 20%;(b) reducing the amount of fluorinated surfactant in the thus obtained aqueous dispersion to an amount of not more than 200 ppm, preferably not more than 100 ppm and more preferably not more than 50 ppm based on the amount of polytetrafluoroethylene solids. The invention further provides an aqueous dispersion of polytetrafluoroethylene particles and the use thereof in coating a substrate.
摘要:
Provided is a fluoroplastic or latex comprising a nitrogen-containing cure site and units derived from a fluorinated monomer. Also provided is a curable blend comprising a fluoroplastic and a fluoroleastomer gum, wherein said fluoroplastic comprises a nitrogen-containing cure site and units derived from a fluorinated monomer. Also provided are cured, shaped articles, latex blends, and a process for preparing a fluoroplastic comprising: (a) introducing at least 60 weight percent of a first polymerizable composition comprising a fluorinated monomer into a polymerization reactor; (b) polymerizing said composition in said reactor; (c) introducing at least 70 weight percent of a second polymerizable composition comprising a nitrogen-containing cure site monomer into said reactor following addition of at least 80% by weight of said first polymerizable composition; and (d) copolymerizing said nitrogen-containing cure site monomer with said fluorinated monomer to form a fluoroplastic.
摘要:
The present invention comprises a substrate having a fluoropolymer on at least one of its surfaces wherein one of the substrates or the fluoropolymer comprises a hydride function MH wherein M is Si, Ge, Sn or Pb. The invention further comprises articles comprising the substrate and fluoropolymer; a method of bonding the fluoropolymer to the substrate; a fluoropolymer composition that contains the fluoropolymer, a polyhydroxy cure composition, and an organic composition comprising the hydride function MH; a premix that contains the fluoropolymer and the hydride function MH; and a fluoropolymer composition that comprises (a) a thermoplastic fluoropolymer comprising Cl, Brand/or I atoms and (b) an organic compound that comprises the hydride function MH.