Direct observation of structure in high‐modulus aromatic fibers

Abstract

Abstract A detailed structural characterization of three aromatic polyamide (PPT) fibers has been carried out by means of direct electron microscope observations and X‐ray and electron diffraction analysis. Data obtained by the diffraction techniques are supplemented by high‐resolution images recorded from fragmented specimens, which provide both a qualitative assessment and quantitative information in terms of crystallite perfection and the distribution of crystallite size. Dark‐field images suggest major differences between the macrostructures of various PPT fibers; indeed some specimens are composed of long‐range axially periodic assemblies, while others appear to be homogeneous. Such differences in organization may well account for variations in tensile behavior.