Analysis of row nucleated lamellar morphology of polypropylene obtained from the cast film process: Effect of melt rheology and process conditions

Five different polypropylene resins were characterized by rheology to study the effect of melt rheology on the row‐nucleated lamellar structure development during the cast film process. The arrangement and orientation of the crystalline and amorphous phases were examined by WAXD (wide angle X‐ray diffraction) and FTIR (Fourier transform infrared) methods. Tensile tests were carried out to examine the effect of orientation on the behavior of the samples. It was found that the molecular weight evaluated from rheology and the processing conditions played a crucial role on the orientation of the crystalline and amorphous phases and, in turn, affected significantly the tensile response. The molecular weight was the main parameter that controlled the orientation and it was found that the resin with a higher molecular weight had a tendency to form a planar crystalline morphology as the draw ratio increased. It was also observed that a planar morphology was associated with a suppression of the yield behavior in the tensile measurements. POLYM. ENG. SCI., 47:1170–1178, 2007.