Origin of the broad endothermic peak observed at low temperatures for polystyrene and metals in Flash differential scanning calorimetry*
Origin of the broad endothermic peak observed at low temperatures for polystyrene and metals in Flash differential scanning calorimetry*
复制标题
在闪示差示扫描量热法中在低温下观察到的聚苯乙烯和金属宽吸热峰的起源*
DOI：
10.1002/pen.26102
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发表时间：
2022
影响因子：
3.2
通讯作者：
Simon, Sindee L.
中科院分区：
文献类型：
--
作者：
Pallaka, Madhusudhan R.;Bari, Rozana;Simon, Sindee L.
用闪光差示扫描量热法研究了聚苯乙烯在4种不同衬底条件下的玻璃化转变行为，研究了不同降温速率对聚苯乙烯玻璃化转变行为的影响，扫描温度分别为30°C和−80°C。此外，对于相同的样品，在20°C下进行结构恢复，老化时间从0.01 S到8小时，扫描到−80°C。在低温(T<；<；Tg)下，随着冷却速度的降低和老化时间的延长，出现了一个宽的吸热曲线，这受薄膜下面的衬底以及扫描实验中结束温度条件的影响。另一方面，与TgS相关的吸热过冲不受衬底温度或扫描端温度的影响。此外，铟和气相沉积金都是结晶材料，随着冷却速度的降低和老化时间的增加，在低温下显示出非常相似的宽吸热增长，这表明低温吸热是一种人工产物，而不是与所研究的材料相关的松弛。文中提出了几种可能的解释。
The glass transition behavior of polystyrene as a function of different cooling rates with scanning to two different end temperatures, 30°C and −80°C, was investigated for four different substrate conditions using Flash differential scanning calorimetry, a fast scanning nanocalorimetry technique. In addition, structural recovery of polystyrene was performed at 20°C for aging times from 0.01 s to 8 h with scanning to −80°C for the same samples. A broad endotherm appears to grow at low temperatures (T<<Tg) as cooling rate decreases and aging time increases, which is influenced by the substrate underlying the film, as well as by the end temperature condition in the scanning experiment. On the other hand, the endothermic overshoot associated withTgis not influenced by substrate or scan end temperature. In addition, indium and vapor‐deposited gold, both crystalline materials, show the growth of a very similar broad endotherm at low temperatures as cooling rate decreases and aging time increases indicating that the low‐temperature endotherm is an artifact and not a relaxation associated with the material under investigation. Several potential explanations are put forward.