Glass transition temperature molecular reorientation mechanism

Understanding the mechanisms of polar order decay is crucial for the tailoring of new exploitable active materials. In contrast with crystals, polymers containing oriented molecules tend to evolve towards a randomization of dipole orientation when the field is removed. Relaxation in such poled systems, following the molecular statistical model, arises from thermal reorientation whose rate is governed by the mobility of the molecules in the matrix. The mobility is in turn determined by a number of parameters including, in particular, glass transition temperature (Tg) and the amount of free volume in the polymer. 

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