Department of Materials Science and Engineering, University of Wisconsin-Madison, 1509 University Ave., Madison, Wisconsin 53706, USA.
J Chem Phys. 2018 Aug 21;149(7):074505. doi: 10.1063/1.5041757.
The polyamorphism exhibited by D-mannitol between the normal melt quenched glass (GN) and the amorphous Phase X (GX) induced by annealing has been examined in a detailed series of differential scanning calorimetry (DSC) measurements covering a wide range of scanning rates. The glass transition of the (GN), T develops an increasing behavior upon annealing, but the glass transition of (GX), T changes little during annealing, implying that (GX) is a kinetically more stable glass. A series of interrupted thermal cycles has allowed for the identification of a liquid-liquid transition between the supercooled liquid of (GN), SCL-1 and that for (GX), SCL-2. The precise annealing conditions that could be reached by Flash DSC enabled the construction of the Temperature-Time-Transformation plot of D-mannitol for the transition between GN/(SCL1) and G X/(SCL2), as well as the transition between amorphous and crystalline phases revealing thermally activated behavior. Under the action of an applied stress, GX can be induced to transform irreversibly into the higher density GN.
在详细的一系列差示扫描量热法（DSC）测量中，研究了 D-甘露醇在正常熔体淬火玻璃（GN）和退火诱导的非晶相 X（GX）之间表现出的多晶型现象，扫描速率范围很宽。（GN）的玻璃化转变温度 T 在退火过程中表现出递增行为，但（GX）的玻璃化转变温度 T 在退火过程中变化不大，这意味着（GX）是一种动力学上更稳定的玻璃。一系列中断的热循环允许确定过冷液体（GN）的 SCL-1 和（GX）的 SCL-2 之间的液-液相转变。快速 DSC 所能达到的精确退火条件使 D-甘露醇在 GN/（SCL1）和 GX/（SCL2）之间的转变以及非晶态和晶态之间的转变的温度-时间-转变图的构建成为可能，揭示了热激活行为。在施加应力的作用下，GX 可以不可逆地转变为密度更高的 GN。
