Fluoropolymers foams

The substitution of a gas for part of the polymeric matrix usually changes the electrical properties. The dielectric constant, dissipation factor, and dielectric strength are lowered roughly proportionally to the amount of gas in the foam. The lower the density of the cellular plastic, the lower the dielectric constant and the better the insulation. Because the dielectric strength is also reduced, the insulation is susceptible to breakdown from voltage surges from lightning and short circuits. Polyolefin foams are preferred for low frequency electrical insulation - PVC, PS foams, silicone and fluoropolymer foams are also used [31, 65, 66]. 

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