• crystalline morphology;
  • extensional rheometry;
  • poly(propylene) (PP);
  • semi-crystalline films;
  • X-ray

The evolution of the crystalline morphology of two poly(propylene) films deformed in the rubbery state using wide- and small-angle X-ray scattering and extensional rheology experiments is presented. The mechanical behavior can be either isotropic or anisotropic depending on the manufacturing process. The microstructure change of the polymer is linked to the thermomechanical behavior of PP films below and close to the melting temperature. The reorientation of the crystalline phase during the deformation is shown to occur quickly when the deformation temperature is largely lower than the melting temperature and for low strain rates. The formation of a fibrillar structure oriented along the stretching direction following the fragmentation of initial crystals is highlighted.mame201300043-gra-0001