Abstract: | Herein, we measured the enthalpy relaxation of three styrene oligomers with different molecular weights (styrene oligomer with Mw?=?4.53?×?102: PSA-300, styrene oligomer with Mw?=?5.89?×?102: PSA-500, and styrene oligomer with Mw?=?1.01?×?103: PSA-1000) near their respective glass transition temperatures (Tg) using an adiabatic calorimeter. We determined the relaxation rates and the amounts of configurational enthalpy released from the temperature dependence of the temperature drift rates around Tg. Based on our experimental findings, we found the amounts of configurational enthalpy release per monomer unit to be 0.8, 3.5, and 1.6 kJ mol?1 for PSA-300, PSA-500, and PSA-1000, respectively. These values were 3.9–18 times larger than that of glycerol, which is a typical glass-forming liquid. |