Hello all,
If we consider a polymer is heated till glass transition temperature at atmospheric pressure. Can we call it Enthalpy of Fusion ( Latent Heat of Fusion). I am confused, as on the internet there is nothing mentioned about transition point.
Thank you
Rajesh
Dear Rajesh Kolkundi, no you can not call it so, fusion or melting is a first order transition, whereas, at Tg it is a second order transition in enthalpy. To simplfy the differences, at Tg only localized zones in the amorphous phase with low cohesion are concerened by this second order transition. On the other hand, melting is the abrupt destruction of the crystalline zones, which have almost the same cohesion energy per mol. My Regards
Dear Rajesh Kolkundi,
The following link help you to compare the glass transition and melting region, which are different. As Mr. Abdelkader BOUAZIZ has mentioned, there isnot any especial defintion for the energy to pass the glass transition.
https://eng.libretexts.org/Bookshelves/Materials_Science/Supplemental_Modules_(Materials_Science)/Polymer_Chemistry/Polymer_Chemistry%3A_Transitions/Polymer_Chemistry%3A_The_Glass_Transition
Glass transition has been thought as somehow resembling a second order phase transition in terms of the Ehrenfest classification, even if this analogy is based at idealized circumstances that can not be realized in practice. Please check:
Article Aspects of the non-crystalline state
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