Network stretching during tensile drawing of polyethylene: A study using X-ray scattering and microscopy

Because of the limitation that many semicrystalline polymers are not transparent, one cannot always study the network stress by optical methods. We suggest to use another tool in such a case. By measuring the azimuthal intensity distribution of the amorphous halo with wide-angle X-ray scattering experiments, one can determine the amorphous chain orientation induced in the strained network, which then results in the network stress. Experiments were carried out for a low-crystallinity polyethylene. They yield the relationships between the orientational order parameter associated with the halo, the birefringence produced by the amorphous chain parts, and the stress. The X-ray scattering results also show that the orientation of the amorphous segments under uniaxial drawing is comparable to the degree of orientation of the crystallites.