Question

If plastic is an insulator, why does it still burn? Something related to resistance?

Answer 1

Insulator insulates against electricity, but has nothing to do with a reaction with oxygen. Many of the best insulators are very flammable.

Answer 2

insulator does not mean fire-retardant nor fire-proof. think about styrofoam cups, they're great insulators but they burn away in seconds

Answer 3

ps. sheng insulators also apply to thermal energy