DEFORMATION MODES IN ORIENTED POLYMERS

To clarify an influence of intermolecular interaction on interfibrillar slip, a comparison study of creep at room temperature in loaded films and fibers built from macromolecules with different molecular structure (flexible and rigid chain) was carried out. These were ultimately drawn melt-crystallized and gel-crystallized ultrahigh molecular weight polyethylene (UHMWPE) films and two commercial (poly)paraphenylene terephthalamide (PPTA) fibers, Kevlar 49 (DuPont) and Armos (JSC “Tverchimvolokno”). An extremely high flow creep rate inhomogeneity was observed in both UHMWPE samples, while creep in the fibers from the rigid-chain polymers developed monotonically. Real-time microscopic observations revealed generation of kink bands in loaded UHMWPE samples. No kinks were observed in Kevlar 49 and Armos. The deformation modes operating in the loaded samples are discussed.