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Q & A: polystyrene foam insulator

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Most recent answer: 10/22/2007
Q:
I would like to know why polystyrene is a better insulator than paper and plastic?
- alice (age 15)
A:
Nice question. Actually polystyrene is a plastic. So far as I know, a plain sheet of polystyrene isnít an unusually good insulator. Itís polystyrene foam that works well. The reason is that air is a good thermal insulator, so long as it isnít allowed to circulate in large-scale convection currents. The foam is almost all air, but itís trapped in tiny plastic pockets, preventing circulation.

Mike W.

Odd- on rereading this question in light of a follow up question, I can't see why I just assumed that you were asking about thermal insulation rather than electrical insulation. As an electrical insulator, polystyrene is better than paper largely because it doesn't degrade by absorbing water.

(published on 10/22/2007)

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