LAUSR

In this study, we analyzed the fibril morphology of different polyacrylonitrile fibers, i.e., two fibers for technical and one for textile applications. The fibers are separated into their fibrils by an ultrasonic etching procedure. For all types of polyacrylonitrile fibers, two different fibril morphologies are found. On the one hand, fibrils with a smooth surface and a homogeneous, amorphous volume structure exist. On the other hand, for the first time in polyacrylonitrile fibers, fibrils with a shish-kebab structure are found. Such fibrils are characterized by a rough surface structure resulting from crystalline lamellar layers oriented perpendicular to a centered shish. With increasing crystallinity of the polyacrylonitrile fibers, the relative amount of shish-kebab fibrils increases. Based on these investigations, a model for the PAN fiber is presented, describing the difference of structure of the two types of fibrils.