The x‐ray diffraction, birefringence, and infrared dichroism of stretched polyethylene

TLDR

The study examines x‑ray diffraction, birefringence, and infrared dichroism in polyethylene samples stretched up to 400 %. By combining any two of the three techniques, the authors can independently determine the orientation of amorphous and crystalline regions, predict the third method’s results, and observe that both regions orient appreciably upon stretching, with amorphous orientation slightly lower, chains becoming fully stretched, crystallinity remaining constant, and CH₂ rocking vibration strength unchanged.

Abstract

Abstract The results of a study of x‐ray diffraction, birefringence, and infrared dichroism on a series of polyethylene samples elongated between 0 and 400% are presented. It is shown that, by using any two of the three methods together, one may determine individually the orientation of the amorphous and crystalline portions of the polymer. The results of the third method may then be predicted. Both amorphous and crystalline regions orient appreciably upon stretching. The amorphous orientation is somewhat lower than that of the crystallites. Many of the amorphous chains appear to become completely stretched out. The results indicate that the degree of crystallinity remains constant during stretching and that the oscillator strength of the CH 2 rocking vibration is also constant.