Aramid fibers fine structure

The interpretation of Donald and Windle [441, 442, 444] and Sawyer et ah [430, 435] is that the bands are associated with a serpentine path of the molecules along the shear direction, consistent with the fine domain structure in the highly oriented TLCP fibers. The analogy to the meander reported for poly(p-phenylene benzo-bisthiazole) (PBZT) [442] and the sharp path caused by the pleated sheet structures of some aramid fibers [447] are aU consistent. It is likely... 

Etching has been used to reveal structures in polymer fibers [179,180], polymer blends [181,182] and in bulk polymers, such as PET [183] and PE [184]. Periodic structures were seen to develop on argon plasma etched, oriented materials, such as nylon and PET, thought to be characteristic of the fold period [185]. Such structures were also shown for ion etched (argon) fibers [186]. Fine scale structures were observed for etched polyamide [187], PET [19,188] and aramid fibers [187] which showed ripple structures transverse to the fiber axis. 

The model extends the structural hierarchy proposed by Dobb, Johnson and Saville [374] for the aramids. Three distinct fibrillar elements have been noted microfibrils, on the order of 50 nm in size fibrils, on the order of 500 nm in size and macrofibrils, about 5 pm (5000 nm) across. The importance of this structural model is that it not only describes the structure of uniaxially oriented fibrous materials, but it also shows the fine structure of the thicker LCP forms of moldings and extrudates. In these thicker materials, process history and temperature affects macrostructures, such as skin-core, bands and layering (Fig. 5.85). The fiber structural model shows the arrangement of the fine structure within those macro units. This structural model improves the understanding of relationships between processes, structure and properties in LCPs. 

The fine structure of aramid fibers. In examining the fine structure of aramid fibers, it is necessary to consider the following fundamental conclusions of the experimental studies in [83, 84] ... 

---