Utilization of “q+/q− = const.” DSC cycles for physical aging studies
Utilization of “q+/q− = const.” DSC cycles for physical aging studies
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DOI：
10.1016/j.eurpolymj.2014.07.039
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发表时间：
2014-10
影响因子：
6
通讯作者：
R. Svoboda
中科院分区：
文献类型：
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作者：
R. Svoboda
利用恒定比率循环温度历史，其中q +/q−=常数，在物理老化研究方面进行了检查。特别是，从恒比（CR）循环的焓松弛的表观活化能的测定进行了讨论。利用CR循环的优点，推导出了一个新的方程，它基于弛豫峰Tp最大值对应的温度随加热速率的变化：−Δh*/R=dln（q+）/dTp−1。该方程被广泛测试的所有类型的结构松弛行为;它被证明是高度准确的，独立于大多数数据失真的影响。此外，它表明，CR周期曲线的独特形状可以用于识别某些数据失真的影响-热滞后，不精确的加热/冷却速率或不完全实现真正的玻璃态在冷却过程中。相应地，这些数据失真效应的校正可以应用于对给定的玻璃质材料和DSC仪器进行的其他物理老化测量。
The utilization of the constant ratio cyclic temperature history, whereq+/q−= const., was examined with respect to physical aging studies. In particular, determination of the apparent activation energy of enthalpy relaxation from constant ratio (CR) cycles was discussed. A novel equation fully utilizing the advantages of CR cycles was derived – it is based on shift of temperature corresponding to the maximum of relaxation peakTpwith the applied heating rate: −Δh*/R=dln(q+)/dTp−1. The equation was extensively tested for all types of structural relaxation behavior; it was proven to be highly accurate and independent from most data-distortive effects. In addition, it was shown that the unique shape of CR cycles curves can be utilized for the identification of certain data-distortive effects – thermal lags, imprecise heating/cooling rates or incomplete achievement of a true glassy state during cooling. Correspondingly, corrections for these data-distortive effects can be applied to other physical aging measurements performed for the given glassy material and DSC instrument.