Fluorosilicone application

Whilst exhibiting the excellent low-temperature flexibility (with a Tg of about -80°C) and very good heat resistance (up to 200°C) typical of a silicone rubber, the fluorosilicones also exhibit good aliphatic oil resistance and excellent aging resistance. However, for some applications they have recently encountered a challenge from the polyphosphazenes (see Section 13.10). 

The use of silicone elastomers for high-voltage applications (insulators and cable accessories) requires special formulations. Unusually, stringent requirements for these materials must be met.509,510 Fluorosilicone rubbers, which offer some unique combinations of properties (e.g., chemical resistance and higher temperature stability), have attracted considerable attention and have been reviewed in recent publications.511,512 It was noted that a modification of perfluoroether elastomers with silicone elastomer via hydrosilylation reaction opens the possibility of novel applications.5... 

Fluorosilicone elastomers generally respond to ionizing radiation in a fashion similar to fhaf of silicone elastomers (polydimethylsiloxanes). One interesting application is a process of preparing blends of fluoroplastics, such as poly(vinylidene fluoride), with fluorosilicone elastomers to obtain materials having a unique combination of flexibility at low temperatures and high mechanical stiength. ... 

It is synthesised from the corresponding D3 cyclosiloxane and exhibits a Tg of -68 °C. Such a polymer can easily be crosslinked by various processes of silicone chemistry (e. g., peroxides, SiH or Si-vinyl derivatives). Fluorosilicones can be used for their resistance to swelling in non polar medium (e.g., Skydrol fluids) even at 100 °C but their main application is to replace elastomers of fluorinated monomers at low temperatures. 

Medium-molecular-weight PMTFPS with vinyl or hydroxyl end blocks are used for adhesives and sealants. They are cured either at ambient temperature (RTV-room temperature vulcanization) or at elevated temperature. One-part moisture-activated RTV sealants have been available commercially for many years. Because of then-very high resistance to jet engine fuels, excellent flexibility at very low temperatures, and high thermal stability, they have been used in both military and civilian aerospace applications.78 Two-part, heat-cured fluorosilicone sealants have been used in military aircraft applications and for sealing automotive fuel systems.79 Special class of fluorosilicone sealants are channel sealants or groove injection sealants, sticky, puttylike compounds, which do not cure. They are used to seal fuel tanks of military aircraft and missiles.75... 

Adhesion of fluorosilicone compounds requires surface treatment. For particularly difficult surfaces plasma treatment is necessary. Flowever, for most common applications, satisfactory bonding is achieved by using a specialized primer.80... 

Fluorosilicones Methanol Application of fluorosilicone primer to metal where intention is to bond unvulcanized rubber. Primer available from Dow Coming... 

MAJOR POLYMER APPLICATIONS microspheres PVC, pol)mrethanes, polyester, silicone, acrylics, epoxy, rubber PTFE powders PA, POM, PC, polyesters, PI, PSF, PSO, PPS, polyurethanes, ECTFE, EPDM, SBR, fluorosilicones, NR... 

MAJOR APPLICATIONS Antifoam fluids, lubricants, protective gels, and elastomers and sealants in applications exposed to hydrocarbon fuels and oils and organic solvents in the automotive and aerospace industries. Longer fluorocarbon side-chain fluorosilicones are available with developing use as release coatings for silicone-based adhesives. 

The range of values given for the siloxyimides covers three different materials tested of that type. Fluorosilicone demonstrated various anomalies which did not permit application of the given equation. The silastyrene showed no detectable moisture solubility. This material was selected as potentially hydrophobic due to its apparent low polarity. It contains methyl groups bonded to a silicon backbone. Although silastyrene has potential,... 

FKMs are coextruded with lower-cost copolymers such as etliylene acrylic copolymer. They can be modihed by blending and vulcanizing with other synthetic rubbers such as silicones, ethylene propylene rubber (EPR) and ethylene propylene diene monomer (EPDM) rubbers, epichlorohydrin, and nitriles. Fluoroelastomers are blended with modihed nitrile butadiene rubber (NBR) to obtain an intermediate performance-cost balance. These blends are useful for underhood applications in environments outside the engine temperature zone such as timing chain tensioner seals. Fluoroelastomers can also be blended with fluorosilicones and other high-temperature polymers to meet engine compartment environments and cost-performance balance. 

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