Lamellar phases of polymers with unusual physical and mechanical properties

Structural transitions that occur in polymers subjected to simple uniaxial tensile deformation are described for the first time. The behavior of folded nanocrystallites with initial sizes of 28×28×17 nm is most interesting. Their thicknesses strongly decrease upon deformation (from 17 nm to less than 10 nm), whereas the longitudinal sizes change only slightly. This gradual flattening of nanoclusters leads to their dislocation melting (as an intermediate stage of the phase transitions predicted by Kosterlitz and Thouless). It is shown by the methods of pole figures and atomic-force microscopy that screw dislocations are spontaneously formed in the region of elastic-plastic deformation to decelerate the first-order phase transition of melting type and that the polymer forms a new lamellar spatially inhomogeneous phase with unusual physical and mechanical properties.