Nanometer-Scale Chain Orientation Transitions during Fracture of High-Density Polyethylene Characterized by Nanodiffraction Imaging

Semicrystalline polymers possess a hierarchical structure made up of crystalline and amorphous regions. During stretching, these internal structures experience various changes, such as crystal rotation and fragmentation, elongation of the amorphous regions, and void formation. Although these deformation behaviors are closely linked to mechanical properties, analyzing their relationship remains challenging due to their nanometer-scale heterogeneity.

Nanodiffraction imaging (NDI), an advanced electron microscopy technique based on position-resolved electron diffraction, allows visualization of polymer crystals and mapping of chain orientation with nanometer-scale spatial resolution. In this study, a high-density polyethylene (HDPE) specimen was prepared and stretched inside an electron microscope to examine its deformation behavior.

At the conference, we will present TEM images illustrating the deformation process, along with NDI maps showing crystal morphologies and molecular chain orientations. Based on these results, we will discuss the mechanisms of deformation and fracture in HDPE.