Studies of optical haze and surface morphology of blown polyethylene films using atomic force microscopy

Atomic force microscopy (AFM) has been used to examine the inner and outer surfaces of commercial blown polyethylene films. When this technique has been used, direct-space images of surface lamellae have been obtained, and the surface roughness determined. The haziness of the films has been measured, both in the as-produced state and when coated with suitable oil. Thus, both surface and bulk contributions to the apparent turbidity have been estimated. The aim of this study has been to correlate in turn the haziness, roughness, and surface morphology. Results obtained showed that the haze is related primarily to the surface roughness and can be reduced by lowering the frost line. AFM images unveiled lamellar features that were oriented predominantly in the transverse direction. The observed wide-angle X-ray diffraction (WAXD) intensities were consistent with an a-axis type of orientation.