Sensitivity of Polymer Crystallization to Shear at Low and High Supercooling of the Melt
Sensitivity of Polymer Crystallization to Shear at Low and High Supercooling of the Melt
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DOI：
10.1021/acs.macromol.8b00195
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发表时间：
2018-03
期刊：
影响因子：
5.5
通讯作者：
A. Rhoades;A. Gohn;Jiho Seo;R. Androsch;R. Colby
中科院分区：
文献类型：
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作者：
A. Rhoades;A. Gohn;Jiho Seo;R. Androsch;R. Colby
流动诱导结晶（FIC）是聚合物自组装的主要机制，但在高过冷度和快速冷却条件下，由于通常用于研究的缓慢加热和冷却条件下发生的结构重排，对该过程的了解很少。采用快速扫描芯片量热技术，确定了特定量的剪切流在85-240 °C的宽温度范围内对聚酰胺66随后结晶的影响。在高温下，异相成核占主导地位，结晶速率随着剪切力的增加而增加。低温结晶，驱动均匀成核，不受先前的剪切流的影响，但剪切的样品能够结晶通过非均质成核路线的温度低于未剪切的材料15 K。先前剪切流的大小也决定了在低于...的速率下冷却期间α/γ晶相的发展和结晶。
Flow-induced crystallization (FIC) is a dominant mechanism of polymer self-assembly, but the process is poorly understood at high supercooling and under fast cooling conditions because of structural rearrangements that occur during slow heating and cooling conditions typically used for investigation. Incorporating fast-scanning chip calorimetry techniques, the influence that specific amounts of shear flow have on the subsequent crystallization of polyamide 66 over a wide range of temperatures, 85–240 °C, is determined. At high temperatures, heterogeneous nucleation dominates and crystallization rate increases with increasing shear. Low-temperature crystallization, driven by homogeneous nucleation, is not influenced by previous shear flow, but sheared samples are able to crystallize via the heterogeneous nucleation route at temperatures 15 K lower than unsheared materials. The magnitude of previous shear flow also dictates α-/γ-crystalline phase development and crystallization during cooling at rates below...