The thermal entropy concept and the T-g transition

According to the present knowledge of polymer physics, the explanation of the T-g transition is based upon the configurational Flory-di Marzio-Adams approach in the overwhelming majority of cases. The majority of papers regarding the T-g transition have been presented along these lines. These papers used a different definition of thermal expansion coefficient from that used in solid state physics. The changes in c(p) values at T-g were related only to the changes in configurational entropy. In our approach the changes in thermal, anharmonic or wobbling types of motion, contributing to the thermal entropy term, have been taken into account and these changes quantitatively result in stepwise variations in the ''alpha'' and ''c(p)'' values. The new theory yields new definitions of alpha and c(p), consistent with the definitions used in solid state physics, while the configurational approach of Flory-di Marzio-Adams can be taken as a complementary and enriching addition to our theory.