Nanoconfined Crystallization in Poly(lactic acid) (PLA) and Poly(ethylene terephthalate) (PET) Induced by Various Forms of Premelt‐Deformation
Nanoconfined Crystallization in Poly(lactic acid) (PLA) and Poly(ethylene terephthalate) (PET) Induced by Various Forms of Premelt‐Deformation
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各种形式的预熔变形诱导聚乳酸 (PLA) 和聚对苯二甲酸乙二醇酯 (PET) 的纳米限制结晶
DOI：
10.1002/marc.202200293
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发表时间：
2022
影响因子：
4.6
通讯作者：
Wang, Shi‐Qing
中科院分区：
文献类型：
--
作者：
Smith, Travis;Feng, Jiansheng;Zou, Lu;Gao, Min;Prévôt, Marianne;Wang, Shi‐Qing
探讨了聚乳酸（PLA）和聚对苯二甲酸乙二酯（PET）的加工-结构-性能关系。具体来说，在仿射变形极限下进行的高于其玻璃化转变温度Tg的无定形PLA和PET的预拉伸和预剪切都可以在退火过程中诱导特定类型的冷结晶，即，纳米限制结晶（NCC），其中晶体尺寸在所有维度上被限制在纳米级尺度，以使加工的PLA和PET光学透明。预熔融变形后的新聚合物结构可以显示出显著增强的机械性能。例如，预熔拉伸产生链网络的几何缩合。这种结构变化可以深刻地改变机械特性，例如，使脆的聚乳酸变韧。相比之下，在高于Tg的无定形PLA的预剪切之后，含有PLA的NCC保持脆性，显示了加工中几何缩合的重要性。进行AFM成像和SAXS测量以验证PLA和PET的预熔融变形确实导致来自退火的NCC，其允许应变诱导的冷结晶在变形链网络的网格尺寸的长度尺度上发生。
The processing–structure–property relationship using poly(lactic acid) (PLA) and poly(ethylene terephthalate) (PET) is explored. Specifically, both pre‐extension and preshear of amorphous PLA and PET above their glass transition temperaturesTg, carried out in the affine deformation limit, can induce a specific type of cold crystallization during annealing, i.e., nanoconfined crystallization (NCC) where crystal sizes are limited to a nanoscopic scale in all dimensions so as to render the processed PLA and PET optically transparent. The new polymer structure after premelt deformation can show considerably enhanced mechanical properties. For example, premelt stretching produces geometric condensation of the chain network. This structural alternation can profoundly change the mechanical characteristics, e.g., turning brittle PLA ductile. In contrast, after preshear of amorphous PLA aboveTg, the NCC containing PLA remains brittle, showing the importance to have geometric condensation from processing. Both AFM imaging and SAXS measurements are performed to verify that premelt deformation of PLA and PET indeed results in NCC from annealing that permits the strain‐induced cold crystallization to take place on the length scale of the mesh size of the deformed chain network.