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Q & A: thermal insulators

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Most recent answer: 10/22/2007
Q:
I have to make a thermos for my science class and I need to know some good heat insulators and how to use them. Do you know how?
- Robbie
Handsworth Secondary, Vancouver, BC
A:
Styrofoam is a very nice thermal insulator. Multiple layers of styrofoam with some reflective sheet between them (aluminized mylar is very good) make a nice insulating wall. The aluminized mylar reflects radiant energy, and the styrofoam blocks convection without causing much conduction.
Maybe aluminum foil could be used for the reflector if the mylar is hard to find, but you would have to be careful that none of the aluminum is in contact with both the hot region and the cold region, since it's a good thermal conductor. Helium balloons are often made of aluminized mylar and can be bought at grocery stores and florist shops -- get a balloon with a big, uniform, uncolored, shiny surface -- sometimes there are holes in the aluminization or printing on top as part of the decoration.

Mike W.

(published on 10/22/2007)

Follow-Up #1: Finding aluminized mylar

Q:
FYI for the thermal insulator question. A great source of reflective mylar are those shiny emergency blankets. They are cheap and can be found at any outdoor store, in first aid kits, department stores, etc. They also offer a lot of material to work with!
- Nathan (age 28)
Independence, OR, USA
A:
thanks

(published on 10/22/2007)

Follow-up on this answer.