Department of Industrial and Physical Pharmacy, Purdue University, 575 Stadium Mall Drive, West Lafayette, Indiana 47907, USA.
J Phys Chem B. 2010 Jan 14;114(1):269-79. doi: 10.1021/jp906633k.
The enthalpy relaxation of amorphous salicin, used as model organic glass of pharmaceutical relevance, was investigated using a combination of DSC measurements and theoretical simulations. The combined approach makes it possible to discern between the effect of the glass forming properties of the material and the effects of the thermal history and experimental conditions. The approach also facilitates an unambiguous definition of the time scale of the experiment, such that objective comparison among relaxation time and glass transition temperature values can be made. The simulation provides accurate predictions of the DSC profiles obtained under a wide variety of experimental conditions. The effects of annealing time and the heating/cooling rate on the enthalpy recovery were explained by tracking the evolution of relaxation times as a function of temperature and time. The combined experimental and simulation approach also makes it possible to systematically explore the effect of specific glass forming properties, such as fragility and nonexponentiality, on the relaxation and associated thermal behavior of molecular organic glasses of pharmaceutical interest. To fully characterize these materials, it is necessary to go beyond the onset T(g) and include the early stages of the glass transition.
采用差示扫描量热法（DSC）测量和理论模拟相结合的方法研究了作为相关药用有机玻璃模型的无定形水杨苷的焓弛豫。这种组合方法可以区分材料的成玻璃性质的影响以及热历史和实验条件的影响。该方法还便于明确实验的时间尺度，从而可以对弛豫时间和玻璃化转变温度值进行客观比较。模拟可以准确预测在各种实验条件下获得的 DSC 图谱。通过跟踪松弛时间随温度和时间的变化来解释退火时间和加热/冷却速率对焓恢复的影响。这种组合的实验和模拟方法还可以系统地研究特定的成玻璃性质（如脆性和非指数性）对药用分子有机玻璃的弛豫和相关热行为的影响。为了充分表征这些材料，有必要超越起始 T(g)并包括玻璃化转变的早期阶段。
