Dual crystalline texture in HDPE blown films and its implication on mechanical properties

The morphological features of a series of high-density polyethylene (HDPE) blown films were studied using transmission electron microscopy, small-angle X-ray scattering and infrared dichroism. An orthogonally-oriented, dual crystalline texture was found in these HDPE films. This structure appears to consist of two superimposed row-oriented textures. In one row-oriented texture, the lamellae are stacked along the machine direction; while in the other, the lamellae are stacked along the transverse direction. The lamellar populations in the two textures are greatly affected by the neck height of the film blowing process. The mechanical properties of the films correlate well with the observed dual crystalline texture.