Heterogeneous density fluctuation of polyethylene under uniaxial stretch

Abstract

Changes in the density fluctuations of polyethy lene on the submicron scale under uniaxial stretch were investigated by means of ultra-small angle X-ray scattermg (USAXS) as a function of stram. Small angle X-ray scattering (SAXS) and wide angle X-ray scattenng (WAXS) were also used in order to get information on a very wide spatial scale from 0.1 nm to 1000 nm. On the submicron scale, heterogeneous density fluctuations developed with strain. The development of the fluctuations was anisotropic; the fluctuations along the stretch direction were larger than along the perpendicular direction. The former fluctuations developed in two steps; the development before the yield point was larger than after the yield point On the other hand, the lamella structure was deformed and the crystal lattice was oriented in proportion to strain.