Answer:
good insulators because they have electrons that are tightly bound in their shells which makes them unable to move between other atoms
Explanation:
In terms of electrical conduction there are almost no free electrons which does not allow the flow of electricity this makes plastic an electrical insulator.
In terms of heat conduction in plastics due to the lack of a free electrons and the electrons are not able to vibrate. Thermal conduction takes place better if vibrations are transmitted easily.