Sequence of enthalpy relaxation, homogeneous crystal nucleation and crystal growth in glassy polyamide 6
Sequence of enthalpy relaxation, homogeneous crystal nucleation and crystal growth in glassy polyamide 6
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DOI：
10.1016/j.eurpolymj.2014.01.012
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发表时间：
2014-04-01
影响因子：
6
通讯作者：
Schmelzer, Juern W. P.
中科院分区：
文献类型：
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作者：
Androsch, Rene;Schick, Christoph;Schmelzer, Juern W. P.
采用快速扫描芯片量热法对玻璃态聚酰胺6的致密化/焓松弛、晶体成核和晶体生长过程进行了定量研究。通过快速冷却使熔体玻璃化，然后将玻璃作为温度和时间的函数进行退火，覆盖六个数量级的时间尺度，这是分离各个弛豫/有序过程所需的。在玻璃退火期间，首先观察到焓弛豫，并且仅在其完成之后才检测到晶体成核，随后是晶体生长。提出了均匀形核机制。在这种情况下，理论上（Gutzow和Schmelzer，2013年）已经表明，玻璃达到亚稳态的特征弛豫时间，即其致密化的特征弛豫时间，通常比成核的特征时间短得多。(C)2014爱思唯尔有限公司版权所有。
The sequence of densification/enthalpy relaxation, crystal nucleation and crystal growth in glassy polyamide 6 has been quantified using fast scanning chip calorimetry. The melt was vitrified by fast cooling, and then the glass was annealed as a function of temperature and time, covering a time scale of six orders of magnitude, required to separate the individual relaxation/ordering processes. During annealing of the glass, there is first observed enthalpy relaxation, and only after its completion there is detected crystal nucleation followed by crystal growth. A homogeneous nucleation mechanism is suggested. In such case, the characteristic relaxation time of the glass to attain metastability, that is, of its densification, has been shown theoretically (Gutzow and Schmelzer, 2013) to be as a rule much shorter than the characteristic time of nucleus formation. (C) 2014 Elsevier Ltd. All rights reserved.