A MORPHOLOGICAL-STUDY OF HDPE-BLOWN FILMS USING SMALL-ANGLE X-RAY-SCATTERING

Discrete small-angle X-ray scattering (SAXS) has been used as an analytical tool to study the development of crystalline morphology in a series of blow-extruded high-density polyethylene (HDPE) films. Processing parameters, take-up ratio (TUR) and blow-up ratio (BUR), were the primary variables used in this investigation. Results from SAXS have led to the consideration of a new microstructural model for crystallite development in blown films. The model incorporates row-nucleated lamellae, where crystalline morphology is sensitive to TUR and BUR. Increasing TUR results in an increase in the number of lamellae in a particular stack, a decrease in fluctuations of amorphous and crystalline thickness distributions, a flattening out of undulations of crystal surfaces, and an increase in the lateral dimensions of lamellae. Increasing BUR did not significantly influence any of the SAXS parameters studied; this can be attributed to the low BURs at which the films were made. (C) 1993 John Wiley and Sons, Inc.