Quantitative Orientational Characterization of Low-density Polyethylene Blown Films By X-ray and Bir

The effect of two important parameters of film blowing process, i.e., take-up ratio and blow-up ratio, on the overall orientation of low-density blown films have been investigated using birefringence measurements. Furthermore, by combining X-ray diffraction pole figure analysis and birefringence, the White and Spruiell biaxial orientationfunctions have been determined for afformentioned sample. Within the range of processing condition studied, increasing take-up ratio, increases orientation in both machine and transverse direction. Upon increasing blow-up ratio, orientation in the transverse direction increases and the overall orientation state approaches to equal biaxial one. Characterization of the crystalline regions by pole figure analysis reveals that a and b crystallographic axes preferentially orientate in the film plane and the direction normal to it, respectively. The amorphous regions do not have any preferential orientation.