What kind of plastic are cd's made from?

Question

I am using a cd for a spark gap on my tesla coil and after running for about 15 seconds my cd is melted and i was wondering what kind of plastic a cd is made from.

Answer 1

Polycarbonates (code 7).

The Wikipedia page about polycarbonates gives you all kinds of figures that should be useful to you, like surface and volume resistivity and the melting temperature.