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.