Real‐time crystalline orientation measurements during low‐density polyethylene blown film extrusion using wide‐angle X‐ray diffraction

Real‐time wide‐angle X‐ray diffraction studies were successfully used to investigate the effect of film blowing process parameter on the crystalline orientation development during the blown film extrusion of low‐density polyethylene. Azimuthal distribution scans showed the evolution of crystalline orientation in the bubble from an isotropic state to an oriented state as inferred from (110) and (200) planes. These real‐time X‐ray diffraction measurements in a blown film line are consistent with prior observations using polarized Raman spectroscopy (Gururajan and Ogale, J. Raman Spectrosc., 40, 212 (2009)) and small‐angle light scattering (Bullwinkel et al., Int. Polym. Proc., 16, 41 (2001)) that significant molecular orientation takes place past the frost‐line height, even after the blown film diameter is locked into place. POLYM. ENG. SCI., 2012.