Heat Transfer-1 (color)

• Polymers:
Thermal conductivity for most polymers is of the order of
0.3 W.m -1 .K -1 . Energy transfer is accomplished by the
vibrations and rotations of chain backbone and side chain
bonds.
The magnitude of the thermal conductivity increases with
the degree of crystallinity.
Polymers are used as low temperature thermal insulators
(porous polymershave enhanced insulative properties).
• Gases:
Thermal conductivity is low but increases with
temperature due to increased Brownian motion resulting in
a higher frequency of contact and increase in molecular
exchange rates. For dilute gases (low pressure, P