Orientation in LLDPE cast films manufactured under different processing parameters

Linear low density polyethylene (LLDPE) stretch films under different processing conditions in terms of line speed, air gap and film thickness are manufactured using a cast film line. The influence of processing parameters on crystal orientation in the cast LLDPE films is evaluated by wide angle X-ray scattering (WAXD). Diffraction patterns reveal no preferred crystal orientation in the cast films. To evaluate the amorphous orientation, shrinkage measurements are carried out in the both machine direction (MD) and transverse direction (TD). It is found that higher line speeds lead to a higher MD shrinkage in the films, and some TD shrinkages are also noticed in the films prepared at high line speeds. However, no significant differences are observed in the shrinkage behavior off films as air gap and film thickness change. The shrinkage detected in the cast films of high line speeds is taken as a measure of chain orientation in the amorphous phase.