Bubble Wrap and Thermal Transfer
Country: United States
Date: June 2006
How does bubble wrap reduce thermal energy transfer?
Air, especially when it is not free to circulate, is a poor heat
conductor. The idea behind many types of insulation -- not just
bubble wrap -- is to trap the air so that it is not free to
circulate. That is what bubble wrap does. It traps the air in the
bubbles so that it cannot circulate, except within each cell. The
same idea applies to foam cups used to serve hot beverages. If you
look at such a cup with a magnifying glass --
crush it so you can see inside the walls of the cup -- you will see
that it is made up of tiny air bubbles too. This prevents the hot
air (or steam) from moving easily from the hot liquid to your hand.
Whenever you go into a room, or outside for example, your body
begins heating the air around it to about the same temperature as
you are. This is why wind feels cool, as the air immidiately around
you is constantly being refreshed, and must be reheated. Warm
clothes, such as a fluffy sweater, trap the air right next to your
body so it is not being replaced so fast.
Bubblewrap, like you asked about, actually contains the same small
amounts of air in tiny plastic bubbles. This prevents the air from
blowing or floating away as it is heated. Since air does not
conduct the heat very well itself, that heat gets trapped right
there with the bubble wrap.
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Update: June 2012