The present work is concerned with the axial compressional behavior of organic high - performance fibers and filmes by means of polarizing optical microscopy

scanning electron microscopy and X - ray diffraction. In the initial stage of compression

kink bands are formed at a proper angle to the draw axis

the molecular chains within the band were broken or bent

that local crystalline slip systems are responsible for the formation of the kink band. With progressive compression

new kink bands were formed near the kink bands that were formed in the initial stage of compression

indicating that compressional stress is concentrated at regions near the kink bands. In the final stage of compression

massive lateral displacement occurred from place to place along fiber axis and the fiber was almost sqeezed out of shape. It can be assumed that intermicrofi- brillar slip plays an important role at the final state of compression.