[xshadow]

Hi!!
At lesson the professor said that the polymers have a different range of melting and crystalization point:

If  H2O(l) becomes a solid at 0°C and at the same time H2O(l) becomes a liquid at 0°C for the polymer the professor said that usaully T_c < T_g

T_c= crystalizzation temperature
T_m=  melt temperature
(actually for the polymers is more correct talk about a range of temperature)

Someone can tell me why is T_c < T_m
Thanks

[Enthalpy]

Macromolecules are too big to have a chance to organize themselves optimally to build a solid, so even when "pure" (BUT the molecule length varies too) they behave like a mixture.

I don't like too much the word "crystallization" for a polymer. Polymers don't build regular crystals; the solid can be more amorphous or more crystalline. Maybe "solidification" fits better.

Also keep in mind that many polymers don't melt. They decompose at heat instead.