Polymerization fluorosilicone elastomers

The most common method of preparation of PMTFPS is through the base-catalyzed ring-opening polymerization of the corresponding cyclic trimer.61-62 Details are in Section 2.11.1. A specific cure site for peroxide curing is developed by incorporating 0.2 mol% of methylvinyl siloxane.63 Typically, fluorosilicone elastomers are copolymers of 90 mol% of trifluoropropylsiloxy and 10 mol% of dimethylsiloxy monomers, but the fluorosilicone content in commercial products ranges from 40 to 90 mol%.63... 

Electrical properties — dielectric constant (e), representing polarization dissipation factor (tan 8), representing relaxation phenomena dielectric strength (EB), representing breakdown phenomena and resistivity (pv), an inverse of conductivity — are compared with other polymers in Table 5.14.74 The low dielectric loss and high electrical resistivity coupled with low water absorption and retention of these properties in harsh environments are major advantages of fluorosilicone elastomers over other polymeric materials.74... 

Some of these polymeric hybrid fluorosilicones were crosslinked to obtain fluorosiloxane elastomers that combine a good flexibility at low temperature, lower than - 40 °C, and a good thermooxidative stability over 250 °C [51,52). They may be proposed as alternative materials with respect to polyfluo-roolefin elastomers. 

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