Abstract
The stability of amorphous ATP, ADP and trehalose were examined from enthalpy relaxation process below the Tg by DSC. The enthalpy relaxation amount (ΔH) was obtained from the endothermic peak area on DSC heating curve that was appeared after aging for 2 to 48 hours below the Tg. The ΔH of every sample increased with aging time through the increasing rate showed significant variation depending on the kind of materials and aging temperature. The ΔH vs. aging time relation was analyzed to obtain a mean relaxation time constant τ by using Kohlrausch-Williams-Watts (KWW) equation. Then the aging temperature dependency of the τ was evaluated by Volgel-Fulcher-Tammann (VFT) equation. Judging from the obtained parameters in KWW and VFT equations, the amorphous state for ATP and ADP below Tg was suggested to be more stable than for trehalose and sucrose, and that the temperature dependency of the enthalpy relaxation rate below Tg were found to be non-Arrhenius type.
