Kang Jia, Yuan Shichen, Hong You-Lee, Chen Wei, Kamimura Akihiro, Otsubo Akihiro, Miyoshi Toshikazu
Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909, United States.
SunAllomer, Ltd., 3-2 Yako 2-chome, Kawasaki-ku Kawasaki 210-0863, Japan.
ACS Macro Lett. 2016 Jan 19;5(1):65-68. doi: 10.1021/acsmacrolett.5b00727. Epub 2015 Dec 22.
Despite numerous investigations on polymer processing, understanding the deformation mechanisms of semicrystalline polymer under uniaxial stretching is still challenging. In this work, C-C Double Quantum (DQ) NMR was applied to trace the structural evolution of C-labeled polypropylene (PP) chains inside the crystallites stretched to an engineering strain () of 21 at 100 °C. DQ NMR based on spatial proximity of C labeled nuclei proved conformational changes from the folded chains to the locally extended chains induced by stretching. By combining experimental findings with literature results on molecular dynamics, it was concluded that transportation of the crystalline chains plays a critical role to achieve large deformability of PP.
尽管对聚合物加工进行了大量研究，但理解半结晶聚合物在单轴拉伸下的变形机制仍然具有挑战性。在这项工作中，采用碳 - 碳双量子（DQ）核磁共振技术来追踪在100°C下拉伸至工程应变（）为21的微晶体内碳标记聚丙烯（PP）链的结构演变。基于碳标记原子核空间接近性的DQ核磁共振证明了拉伸诱导的从折叠链到局部伸展链的构象变化。通过将实验结果与分子动力学的文献结果相结合，得出结论：结晶链的迁移对实现PP的大变形能力起着关键作用。
