Supramolecular structure of a high‐modulus polyaromatic fiber (Kevlar 49)

The supramolecular organization of the aromatic polyamide fiber Kevlar 49 has been studied using a combination of electron diffraction and electron microscope dark‐field image techniques. The dark‐field images derived using selected reflections from longitudinal sections exhibit axial banding of two main types having periodicities of 500 and 250 nm. Careful analysis, including tilting experiments, conclusively shows that the supramolecular architecture of these fibers consists of a system of sheets regularly pleated along their long axes and arranged radially.