Under the supervision of Researcher Chen Wei and Associate Researcher Li Liangbin, our Ph.D. candidate Li Chengyan and colleagues combined low-field proton nuclear magnetic resonance (1H NMR) with wide-angle X-ray scattering (WAXS) to investigate the chain structure and dynamic evolution of low-density polyethylene (LDPE) during uniaxial stretching. In this work, in situ low-field 1H NMR spectroscopy was further applied to explore the deformation mechanism of LDPE, revealing the great potential of this technique in such studies. The related work has been published in Macromolecules.
In this article, the dynamic component information of LDPE during stretching was systematically studied. After necking, discrepancies between the rigid component detected by 1H NMR and the crystallinity measured by WAXS gradually increased, indicating the formation of a dynamically highly constrained amorphous fraction. Based on dynamic differences, the amorphous region can thus be divided into three parts: highly constrained amorphous, rigid amorphous, and flexible amorphous. The evolution of these components exhibited clear strain dependence. In situ 1H NMR experiments on uniaxial stretching of LDPE further showed that in the elastic regime the dynamics remain nearly unchanged, whereas after plastic deformation the dynamics of the amorphous phase become strongly restricted.
Li, C.; Xia, Z.; Wu, L.; Xiong, Y.; Chen, W. Strain-Dependent Evolution of the Rigid Amorphous Fraction of Low-Density Polyethylene under Deformation. Macromolecules 2025, 58 (5),2320–2335. https://doi.org/10.1021/acs.macromol.4c02773.
Paper Link：https://doi.org/10.1021/acs.macromol.4c02773.
