The present disclosure provides elastomer blends comprising mixtures of partially fluorinated elastomers, such as tetrafluoroethylene propylene elastomers (FEPM or TFEP) and fluorocarbon rubbers, such as vinylidene fluoride-based elastomers (FKM or FEP). The elastomer blends can be prepared using two-roll mills, internal mixers, or other mixing technique and can be molded into seals, gaskets, o-rings or other articles using extrusion, injection molding, compression molding or the like. The resultant elastomeric articles can provide good sealing performance, including at moderate or low temperatures, and exhibit good chemical compatibility and resistance when exposed to common wellbore environments. In some cases, the elastomer blends can provide performance characteristics previously only available from perfluorinated elastomers (FFKM), but without requiring the complex processing conditions associated with preparing perfluorinated elastomers.

The present invention relates to a flame-retardant polycarbonate composition comprising the following components, relative to the total weight of the composition: A) 30-70 wt. % of at least one aromatic polycarbonate, B) 20-60 wt. % of at least one polysiloxane-polycarbonate block condensate, C) 0.5-5 wt. % of at least one cyclic phosphazene, D) 1-5 wt. % of at least one silicone-acrylate rubber based impact modifier, E) 0.3-3 wt % of kaolin, F) 0.1-1 wt. % of at least one anti-dripping agent, and G) 0.1-1 wt. % of at least one UV absorber.

The present invention also relates to a shaped article produced from the composition. The polycarbonate composition according to the present invention has a good combination of low-temperature impact performance, flame-retardancy, hydrolytic stability, anti-UV performance, and heat resistance.

The present invention relates to a flame-retardant polycarbonate composition comprising the following components, relative to the total weight of the composition: A) 30-70 wt. % of at least one aromatic polycarbonate, B) 20-60 wt. % of at least one polysiloxane-polycarbonate block condensate, C) 0.5-5 wt. % of at least one cyclic phosphazene, D) 1-5 wt. % of at least one silicone-acrylate rubber based impact modifier, E) 0.3-3 wt % of kaolin, F) 0.1-1 wt. % of at least one anti-dripping agent, and G) 0.1-1 wt. % of at least one UV absorber.

The present invention also relates to a shaped article produced from the composition. The polycarbonate composition according to the present invention has a good combination of low-temperature impact performance, flame-retardancy, hydrolytic stability, anti-UV performance, and heat resistance.

A method for producing a fluoropolymer which includes polymerizing a fluoromonomer in an aqueous medium in the presence of a surfactant to provide a fluoropolymer, the surfactant being represented by the general formula (1): CR.sup.1R.sup.2R.sup.4—CR.sup.3R.sup.5—X-A, wherein R.sup.1 to R.sup.5 are each H or a monovalent substituent, with the proviso that at least one of R.sup.1 and R.sup.3 represents a group represented by the general formula: —Y—R.sup.6 and at least one of R.sup.2 and R.sup.5 represents a group represented by the general formula: —X-A or a group represented by the general formula: —Y—R.sup.6; and A is the same or different at each occurrence and is —COOM, —SO.sub.3M, or —OSO.sub.3M. Also disclosed is a surfactant for polymerization represented by the general formula (1), a method for producing a fluoropolymer using the surfactant and a composition including a fluoropolymer and the surfactant.

A method for producing a fluoropolymer which includes polymerizing a fluoromonomer in an aqueous medium in the presence of a surfactant to provide a fluoropolymer, the surfactant being represented by the general formula (1): CR.sup.1R.sup.2R.sup.4—CR.sup.3R.sup.5—X-A, wherein R.sup.1 to R.sup.5 are each H or a monovalent substituent, with the proviso that at least one of R.sup.1 and R.sup.3 represents a group represented by the general formula: —Y—R.sup.6 and at least one of R.sup.2 and R.sup.5 represents a group represented by the general formula: —X-A or a group represented by the general formula: —Y—R.sup.6; and A is the same or different at each occurrence and is —COOM, —SO.sub.3M, or —OSO.sub.3M. Also disclosed is a surfactant for polymerization represented by the general formula (1), a method for producing a fluoropolymer using the surfactant and a composition including a fluoropolymer and the surfactant.

A process is provided for the polymerization of fluoromonomer to an dispersion of fluoropolymer particles in an aqueous medium in a polymerization reactor, by (a) providing the aqueous medium in the reactor, (b) adding the fluoromonomer to the reactor, (c) adding initiator to the aqueous medium, the combination of steps (b) and (c) being carried out essentially free of hydrocarbon-containing surfactant and resulting in the kickoff of the polymerization of the fluoromonomer, and (d) metering hydrocarbon-containing surfactant into the aqueous medium after the kickoff of polymerization, e.g. after the concentration of the fluoropolymer in the aqueous medium is at least 0.6 wt %, the metering being at a rate reducing the telogenic activity of said surfactant while maintaining surface activity.

A process is provided for the polymerization of fluoromonomer to an dispersion of fluoropolymer particles in an aqueous medium in a polymerization reactor, by (a) providing the aqueous medium in the reactor, (b) adding the fluoromonomer to the reactor, (c) adding initiator to the aqueous medium, the combination of steps (b) and (c) being carried out essentially free of hydrocarbon-containing surfactant and resulting in the kickoff of the polymerization of the fluoromonomer, and (d) metering hydrocarbon-containing surfactant into the aqueous medium after the kickoff of polymerization, e.g. after the concentration of the fluoropolymer in the aqueous medium is at least 0.6 wt %, the metering being at a rate reducing the telogenic activity of said surfactant while maintaining surface activity.

A process is provided for the polymerization of fluoromonomer to an dispersion of fluoropolymer particles in an aqueous medium in a polymerization reactor, by (a) providing the aqueous medium in the reactor, (b) adding the fluoromonomer to the reactor, (c) adding initiator to the aqueous medium, the combination of steps (b) and (c) being carried out essentially free of hydrocarbon-containing surfactant and resulting in the kickoff of the polymerization of the fluoromonomer, and (d) metering hydrocarbon-containing surfactant into the aqueous medium after the kickoff of polymerization, e.g. after the concentration of the fluoropolymer in the aqueous medium is at least 0.6 wt %, the metering being at a rate reducing the telogenic activity of said surfactant while maintaining surface activity.

In an embodiment the dielectric layer comprises a fluoropolymer, a plurality of boron nitride particles, a plurality of titanium dioxide particles, a plurality of silica particles; and a reinforcing layer. The dielectric layer can comprise at least one of 20 to 45 volume percent of the fluoropolymer, 15 to 35 volume percent of the plurality of boron nitride particles, 1 to 32 volume percent of the plurality of titanium dioxide particles, 10 to 35 volume percent of the plurality of silica particles, and 5 to 15 volume percent of the reinforcing layer; wherein the volume percent values are based on a total volume of the dielectric layer.

In an embodiment the dielectric layer comprises a fluoropolymer, a plurality of boron nitride particles, a plurality of titanium dioxide particles, a plurality of silica particles; and a reinforcing layer. The dielectric layer can comprise at least one of 20 to 45 volume percent of the fluoropolymer, 15 to 35 volume percent of the plurality of boron nitride particles, 1 to 32 volume percent of the plurality of titanium dioxide particles, 10 to 35 volume percent of the plurality of silica particles, and 5 to 15 volume percent of the reinforcing layer; wherein the volume percent values are based on a total volume of the dielectric layer.