The measurement of the orientation rate of crystals in a crystalline polymer by dynamic x‐ray diffraction

Dynamic birefringence measurements on crystalline polymers such as polyethylene indicate that there is a characteristic time for change in molecular orientation. This time has been ascribed to that required for crystals to change their orientation following the deformation of the polymer. In order to test this proposal a direct measurement of this orientation time by x-ray diffraction during the steady state vibrational strain of the sample was attempted. The measurement was carried out by an 'x-ray stroboscope' principle in which the intensity of the diffracted x-rays was measured during a small part of the vibration period but repeated during successive period.